Very important question but not in my area. The papers at Link may be very useful.

Outfall alternatives are evaluated for a municipal wastewater treatment facility that discharges effluent at the shoreline of an urban lake.

http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCkQFjABahUKEwj61Mj5s8jHAhULHZQKHWEjD4U&url=http%3A%2F%2Fwww.scirp.org%2Fjournal%2FPaperDownload.aspx%3FpaperID%3D36726&ei=X4_eVbqpG4u60AThxryoCA&usg=AFQjCNHg0C2Zx_q_ucYnJ5WA9HfJvgpovA

http://www.epa.gov/region9/water/npdes/pdf/sand-island/SandIslandFactSheet.pdf

http://www.dep.state.fl.us/water/reuse/docs/OceanOutfallStudy.pdf

Agree with you Subhash C. Kundu

I am not an expert to address this aspect.  This is just to share my view point.

There are many questions to be answered before we can arrive at the answer.  Where is the municipal waste being discharged?  Is it a biological waste?  What is the composition of the waste?  It is true that the waste is let into the sea/ocean.  There is no alternative to it, if it is a bio waste.  It is generally allowed into the sea water at low tides. If it is an industrial waste with a high degree of concentration of inorganic compounds, what are the implications? Possibly it is also done in a similar manner as that of bio waste.  This can contaminate the coastal region.  Possibly, it is diluted before discharge into the ocean to the extent possible.

Studies must have been undertaken at selected regions to determine the impact of discharge of bio and inorganic waste.  One can expect changes in the marine life near the region of discharge.  Since ocean volumes are much larger than the volume of discharge, it can dissipate the waste and dilute it to the extent possible.  Human beings are habituated to comforts and industrialization cannot be stopped.  We all know that the ecosystem is continuously changing and marine life is adapting to the changes or facing extinction.  What we have to do is to find technical solutions to these problems as quickly as possible, educate the people for minimization of discharge to the environment and try to find alternate innovative solutions.  The cost may be a matter of concern to a private organization. Possibly, Governments can involve with the private organizations to workout an operational strategy in preserving the eco systems. 

Thank you Dr. Antonio for posting this question.

Sewerage systems can be divided into three main types: Conventional Gravity Sewerage, Vacuum sewerage and small bore sewerage. The most common type of sewerage system is Conventional gravity system and for sewage treatment it is activated sludge treatment with aeration. Sewage treatment plants installed fail due to low level of maintenance. Hence it is crucial to provide training to the operators while considering to invest in the infrastructure. 

The question is very good and interesting and will follow it, but cannot provide an answer since  (as a research economist) am not qualified...all I can think of is the risk of eutrophication but maybe this is low in the case of ocean discharges...

@all good responses

The municipal wastewater is very important for keeping the cleaning of environment, but this must be done according to scientific studies to ensure the absence of negative effects of this discharge, and maximum make use of its waste.

Dear Colleagues,

Good Day,

Q. What is wastewater?

We all create wastewater in our everyday lives. At home, we access water with ease; we twist the tap, we flush the toilet, we hit the button on the washing machine and we twist the nozzle on the shower. Industry, hospitals, schools and offices also create wastewater. Wastewater can contain a wide range of contaminants, some of which can be broken down in the environment easily while others are not so easily degraded.

Q. Why do we need to treat wastewater?

Untreated wastewater poses a threat to public health and the environment. Treatment is therefore carried out in order to produce an environmentally safe liquid that is suitable for disposal to our aquatic environment, such as rivers and seas. Proper wastewater treatment systems are essential for sustaining modern living and contributing to development as householders, businesses, industries, schools and hospitals all rely on a robust wastewater treatment system to maintain their daily activities.

Stages of treatment

There are three main phases of treatment undertaken in wastewater treatment plants:

When the wastewater reaches the plant, it initially goes through a preliminary treatment stage; it is passed through a mechanically raked screen to remove any large solids.

Phase two sees the wastewater held in a tank where any remaining solids sink to the bottom while fats, oils, grease and lighter solids float to the surface. All of these are removed before the wastewater carries on to its final treatment.

Phase three is a biological treatment phase to cleanse the wastewater further.

Finally, the treated wastewater is then transported through an underground pipeline and discharged out to sea.

What determines the level of treatment required?

The level of treatment will be determined by the EPA licence which takes account of the designation and quality of the receiving water.

Please, see the following links for further information:

http://www.greaterdublindrainage.com/faqs/

http://worldwidescience.org/topicpages/w/wastewater-treatment+plant+discharge.html

http://iwlearn.net/iw-projects/3766/technical-reports/baseline-assessment-study-on-wastewater-management-jamaica

https://www.umweltbundesamt.de/sites/default/files/medien/publikation/long/3770.pdf

Agree with Dr Kundu, Krishnan, and  Hazim.

Thanks for all answers. Answering to my question: In my opinion, still generally allowed, particularly in the European space (as far as I suppose, unless any recent alteration of legislation have occurred), but is not the best practice. In my opinion, secondary treatment should be the minimum level of treatment before the submarine outfall. In my opinion, the problem begins with the old combined systems that should be all converted to separate systems. Similarly to one of the links posted by Subhash, the previous Portuguese legislation pointed for the secondary treatment as the minimum level of treatment for sanitary sewage, independently of the receptor mean of discharge. Later, with the transposition of a European Norm to our legislation, it is allowed only the primary treatment for discharges in water bodies with a good renewal of waters, as the Oceans, and it may be required the tertiary treatment (with removal of nutrients) in sensitive zones, such as interior lakes (to avoid eutrophication as pointed by Simona).

Dear Mario: In fact, you pointed in a very didactic way for very important issues with respect to pollution control in the long run. The wastewater may include contaminants related with chemical pollution due to affluence of industrial flows. The knowledge and control of these inflows and of the characteristics of municipal wastewater are fundamental (even if the pollutants might present low concentrations, in large combined systems, particularly for wet-weather flows, due to the enormous volumes of pluvial water collected).

I do not see any problem given proper design of the outfall ( required dilution  level) to meet regulatory standards. 

In a most cases in cities with ocean outfalls where following heavy rains combined stormwater/sewage or wastewater plant effluent is discharged through outfalls ,  the beaches are closed until the fecal coliform levels have dissipated. Cities have aging infrastructure with leaky pipes have increasing infiltration and inflows which overstresses WWTPs.

There are a number of hydraulic models used to determine the effluent plume dispersion and dispersion for outfalls. I recommend going to the USEPA for information and research manuals and also USGS. I will provide a few links below for the EPA Manual including studies of Boston Harbour Outfall.

http://water.epa.gov/scitech/swguidance/standards/upload/2007_01_17_standards_mixingzone_RSB_UM_PLUMES.pdf

http://pubs.usgs.gov/fs/fs185-97/

http://woodshole.er.usgs.gov/project-pages/bostonharbor/

Venice Lagoon Outfall:

http://www.mikepoweredbydhi.com/upload/dhisoftwarearchive/papersanddocs/ecology/VeniceLagoon.pdf

Dear Faleke: Thanks very much for your answer. I suppose that many colleagues Engineers will agree with you.

Dear Mario: Thanks for your conceptual answer. However, it is mandatory/advisable identifying exactly the industrial pollutants, and the way to control them.

Dear Mohan: Thanks for sharing your valuable experience (particularly in WWTPs) and opportune references. I agree with your concerns. Even for separate sanitary systems, in systems in bad state, Infiltrations/Inflows (particularly for wet-weather flows) may impede the WWTP of operating in conditions minimally satisfactory.

The two overriding factors, for the practice of directing primarily treated waste water into  estuaries or oceans, are: cost & laziness. Governments do not usually admit the existence of bad management & sloppy planning and they sell their governance as incessant success stories. We are already witnessing harm inflicted upon the marine  ecosystems (such as suicidal whales).

By just allocating little cost & some extra effort by knowledgeable persons, the waste water could be further converted into a type of water that is suitable for irrigating many kinds of plants instead of sending them into seas or oceans.

Just from my limited knowledge of water treatment, I think primary treatment may not destroy all the toxins in the water, so that the water may have a harmful effect wherever it goes.

Many thanks,

Debra

Traditional water treatment facilities are not capable of sufficiently treating alternative water supply sources.  State‐of‐the‐art and more costly reverse osmosis water treatment facilities will be needed to obtain increased water supply. Climate change and sea level rise are expected to pose serious challenges to economy, environment, and communities

http://www.sfrpc.com/CEDS/SouthFloridaCEDS2012-17.pdf

Highly treated waste-water effluent from municipal waste-water treatment plants can be reused as a reliable source of water for agricultural irrigation, landscape irrigation, industrial recycling and reuse, groundwater recharge, recreational uses, non-potable urban reuse or even potable reuse. Treated waste-water effluent can be used for the irrigation of crops or landscaped areas. The main consideration associated with this effluent application method is the quality of the treated water and its suitability for plant growth.

http://www.idosi.org/ijwres/2(2)13/1.pdf

Given the facts that

* municipal wastewater (meaning primarily human excreta) is biodegradable but presents a high infectious risk;

* that treatment is ineffective, inefficient and costly; and

* that globally most (meaning more than 50%) of such wastewater is entirely untreated and even where treatment is applied, much treatment is mis-managed and  by-passed by stormwater flows(note that the latter of frequent in some wealthy nations as well as lower and middle income countries) (see http://pubs.acs.org/doi/pdf/10.1021/es304284f for more on this)

... I have always been in favour of properly designed and constructed long sea outfalls - where tidal and current conditions are adequately charcaterised and preclude short-circuits to human exposure (eg shellfish beds, recreational waters) or substantive adverse environmental impacts.

The arguments concerning hazardous waste, and toxic chemicals that accumulate in the foodchain in particular, limit the simple application of this comment to places (the minority) where municipal wastewater has a minimal input of such wastes.

Thanks for the simplicity and excellent level of your answer, Dear Jamie: I understood and agree with most of your considerations, but it should be complemented that that some of your assumptions are valid only partially.

The link bellow: “Functional Appraisal of Marine Outfall For Domestic Waste Disposal

through Tracer Technique” relative to (included in) the “ International Conference on Desalination, Environment And Marine Outfall Systems, April 2014, SQU Muscat Oman” includes some elementary information about advantages and disadvantages of marine outfalls and also some Locations of Submarine Outfalls:

“1 Africa • Casablanca (Morocco).

2 Asia • Manila Bay (Philippines).

• Mumbai (India),

• Mutwall, Wellawaththa, Lunawa (Sri Lanka).

3 Australia • Sydney.

4 Europe • Barcelona, San Sebastian, Spain

• Costa do Estoril (Portugal),

• the Marmara Sea near Istanbul (Turkey),

• Split (Croatia), Edinburgh, Scotland.

• the Thames Estuary downstream of London (UK),

5 North America • Honolulu ,the New York Bight, Southern California Bight (USA),

• Victoria, British Columbia, (Canada).

6 Latin America and the Caribbean

• Cartagena, Colombia,

• Ipanema beach from Rio de Janeiro (Brazil)*.

• Sosua (Dominican Republic).”

 PhD Thesis of the Australian engineer Sharon Beder (University of New South Wales, Australia, 1989): “From Pipe Dreams to Tunnel Vision: Engineering Decision-Making and Sydney's Sewerage System”, starting from a case study, has like comprehensive theme the analysis of engineering decision-making in this area.

https://www.squ.edu.om/Portals/89/PDF/Conferences/Waste_Disposal.pdf

http://www.herinst.org/sbeder/sewage/phd.html#.VeMXEvlViko

Just came across an news article on sewage contamination in RIo de Janeiro which are supposed to be fixed in time for the 2016 Olympics.

http://www.usatoday.com/story/sports/olympics/2015/08/21/head--rios-water-utility-sees-problems--olympic-bay/32102063/

Guess if it is still not fixed in time a heavy chlorine dose injected into the start of the outfalls may be the last resort. Interesting to follow how they will resolve this issue if they  don't have all the treatment processes running in time.

Reading some of the comments, the fact is that a secondary treated wastewater effluent is cleaner than many receiving waters where people swim in but it needs to be heavily disinfected to zap all the fecal coliforms. Its all site specific. 

Since faecal (thermotolerant) coliforms are indicators, not pathogens; and since they are also far more sensitive to chlorine than many pathogens, 'zapping them' will likely lead to a false sense of security and under-estimation of risk.  If the comment on 'cleanliness' of secondary treated effluents is based on coliform counts in chlorinated waters the same comment would apply.

the best way is to prevent any discharge to the sea....it is preferable to reuse treated wastewater in irrigation purposes , provided that only to irrigate the non food plants

I am from Mumbai where some sewage is disposed through Marine Outfalls. This project was done with the support of World Bank. I do not have scientific evidence to suggest that these marine outfalls affect the marine ecosystem. But I feel as there is huge unmet demand for water in Mumbai, sewage should be considered as resource. Since the cost of water is on the rise, it will be economical to reuse the sewage rather than wasting in the sea. In fact there are many industries in Mumbai which are purchasing sewage from Municipal Corporation of Greater Mumbai (MCGM) as they find economical to treat and use the sewage water for industrial purposes rather than purchasing treated water from MCGM. However this is the case for Mumbai. 

Well you need to use an indicator and there are several degrees of disinfection and contact times depending on the  TSS with different chemical disinfectants and also UV light radiation. Parasites like cryptosporidium a inactivated by UV. Depending on how well municipalities have implemented an industrial pre-treatment program, domestic wastewater should be primarily be from people. If combined sewer overflow, then their is oil  in the runoff from paved areas. In the US, they are now monitoring traces of medicine people take which is found in the effluent discharged. You also have fish toxicity tests for discharge evaluation. I have been on the Water Environment Federation's Committees updating the manuals of practice for design and O&M of wastewater - the technologies are out there - it is how much a community is willing to spend and tax themselves in the pursuit of happiness. 

The fact is that the degree of treatment provided is site specific. Dilution is not the answer unless you have outfall miles away. In cities along rivers using the water as a raw drinking water source, the water plant withdraws upstream and the WWTP discharges downstream. The next City downstream does the same and so on - basically the cities/towns downstream are using as their raw water source what is a mix of river water and treated water downstream. The dilution factor becomes ineffective when populations grow.

Then you have the bioaccumulation - it is fact that untreated or partially treated discharges will cause bioaccumulation in the sediment in the non-rainy season. When the rainy season comes, the high flows churn up the sediment and you suddenly find dead fish floating from sudden high demand for oxygen or high toxicity. In Florida, they are blaming the seasonal Red Tide (algal blooms) in the Gulf of Mexico  from fertilizer runoff bioaccumulation. 

Yes, tertiary treated wastewater is a good raw source  drinking water which will mitigate aquifer depletion. Its how people take or are educated ( in the example given above many unknowingly  are  drinking water made from an upstream city's treated discharge. The US Space Station astronauts are said to be drinking water made from recycled urine. Some places are now sending treated wastewater to wetlands to recharge aquifers or reuse after some time.   Singapore and Namibia are already recycling wastewater to drinking water per links below.

http://www.cnn.com/2014/09/23/living/newater-singapore/

http://www.earthmagazine.org/article/drinking-toilet-water-science-and-psychology-wastewater-recycling

The following paper (in Portuguese) entitled 

“13 ANOS DE MONITORIZAÇÃO DA DESCARGA DO EMISSÁRIO SUBMARINO DA GUIA - INTEGRAÇÃO NA DQA”, by

Cristina SANTOS, Justina CATARINO, Alexandra BARREIROS, Maria A.TRANCOSO, Eugénia MARQUES, Carla GARCIA, Ramiro NEVES, Vânia CARVALHO, Catarina LOPES, presented in

“10º Congresso da Água, Algarve, 2010.”

is available in Internet and has interesting information about 13 years of operation of the submarine outfall of “Costa do Estoril”, near Lisbon, Portugal, that began to operate in 1994.

According to the paper:

“A Directiva Quadro da Água 2006/60/CE (DQA) é o instrumento orientador na União Europeia para gestão das águas superficiais interiores, águas de transição, águas costeiras e águas subterrâneas. Foi transposta para o normativo português pela Lei 58/2005 (Lei da Água) e Decreto-lei 77/2006.

(…)

Neste trabalho pretende-se dar a conhecer alguns resultados do maior programa de monitorização português levado a cabo por uma empresa gestora de águas residuais, SANEST, bem como a sua evolução ao longo de 13 anos. Planeado antes da aprovação da DQA, este programa demonstrava já algumas das preocupações nela patentes – quantificar a variabilidade espacial e temporal de parâmetros de qualidade tendo em vista o controle das massas de água para usos futuros (MV) e avaliar o sucesso do programa de medidas adoptado (MO).

A SANEST é uma empresa de saneamento público responsável pela gestão de um sistema de águas residuais localizado na Guia (Cascais), na costa oeste de Lisboa, Portugal. Inclui um interceptor com 25 km, uma estação de tratamento subterrânea e um emissário submarino com 2,8 km a descarregar a 40 m de profundidade. O emissário opera desde 1994 e descarrega no Oceano Atlântico aproximadamente 170000 m3 por dia de um efluente urbano. O sistema de saneamento serve cerca de 720000 habitantes equivalente (h.e.) de quatro municípios na região oeste de Lisboa, esperando atingir 920000 habitantes equivalente em 2020, sendo, portanto, uma das maiores empresas de saneamento em Portugal. As águas residuais urbanas são submetidas a um tratamento preliminar que inclui um step-screen para remover sólidos (3 mm) e uma desarenação antes de eliminação (Santos e Catarino,2009).

O emissário localiza-se numa zona em que as condições hidrodinâmicas da costa resultantes das marés, ventos e correntes de densidade costeiras associadas à acção de ondas de vento, são das mais favoráveis das águas costeiras europeias para diluição e dispersão das águas residuais. Classificado como área menos sensível pelo INAG (Decreto-Lei 152/97), é uma zona conveniente para a localização de um emissário submarino.”

In the second link: “Combined Sewer Overflows (CSOs) Discharging to the Lower Charles River Basin”, near Boston, USA.

http://repositorio.lneg.pt/bitstream/10400.9/1114/1/Santos%20et%20al%2010%20CAgua.pdf

http://www.bwsc.org/ABOUT_BWSC/systems/outfall_maps/CSO_CHARLES.pdf

Wastewater disposal by marine outfalls is proven and effective and is a reliable and cost effective solution with minimal environmental impacts. The design and siting of submarine outfalls is a complex task that relies on many disciplines including oceanography, civil and environmental engineering, marine biology, construction, economics, and public relations. Marine Wastewater Outfalls and Treatment Systems brings these disciplines together and outlines all tasks involved in the planning and design of a wastewater system involving a marine outfall.

http://www.iwapublishing.com/books/9781843391890/marine-wastewater-outfalls-and-treatment-systems

Dear Mohan: Thanks for sharing your expertise. In fact, great volumes of fresh water are currently required for all human activities (including agricultural irrigation. irrigation of green spaces, and industrial activities), and reuse of treated wastewater is a rational solution environmentally sustainable. The type and degree of treatment must be in according to the characteristics of the wastewater and with the intended use, in order to satisfy all patterns of quality demanded in the legislation and regulations. The reuse of treated wastewater may be particularly suitable and economically favourable for regions of scarce water resources.

I must admit some of these answers are not well informed and a bit off base.  It seems everyone has an opinion.  My opinion has changed though through the years.  I originally believed that the solution to pollution is not dilution but have since changed my mind.  To illustrate this I want to offer the following case study.  Victoria, Canada has deep sea outfalls and is struggling with the cost of upgrading primary treatment to secondary treatment at a cost of about  $1B.  Studies done on the outfall cannot detect any effect of said primary effluent beyond a radius of about 40 m.  There is a strong and well organized consortium that is fighting the efforts to upgrade.   I think they are going to loose.

I also think the term dilution has been also been misused.  Deep sea outfall discharge is  not just dilution.  In fact,  all biological sewage treatment systems are our way of mimicking natural processes that occurs in our oceans.  In fact our oceans are the best sewage treatment plants we have, and its free.  I changed my mind after seeing what happened in Vancouver after they upgraded to secondary treatment years ago.  They are still paying for it and the benefits are not really there.  I agree with everything Jamie Bartram writes.  For a microbiologist he really thinks like an engineer.  

Thanks for expressing with sincerity your opinion about this issue, Dear Angus. All the members of scientific and academic community (from whom we make part) are intelligent persons. Sometimes, when I do not feel myself absolutely comfortable in some scientific subject, I have much more careful in formulating and expressing an opinion and thus the probability of the occurrence of any possible error (even if minimal) can even decrease considerably. The same apply to many RG colleagues, I suppose. Also, sometimes we do not say directly everything that we think or know about a scientific issue, because of the public responsibilities we have or because of a matter of courtesy with our colleagues or with many people that share correlated professions?

Capacity of self-depuration also exists in rivers and lakes, and we can see the results if we do not treat the waste water. Okay, seas and oceans are incomparable larger (and the salt and diffusers may help until some extent?), but if the pressure over the coastal eco-systems go on increasing and if no actions are taken, I do not see a great environmental future for such systems. There is already currently much (excessive?) garbage at sea in many parts of the planet?

Upon reviewing the notings, I wish to add that HRT in any process is important. I reckon when natural processes are used, 8 to 10 days are minimum to be given. Thus we can plan a combination of all of them or a few or only primary process. In all these the process or processes, one needs to remove the accumulations that arise in the process and let the effluent be led to the out-falls. If this is duly done, the outcome would be better.We have observed this in some of our projects.   

Dear Dr. Antonio, in general, quality of surface water in downstream is highly concentration of polluted, primary treatment only, will not reduce concentration of all parameter in the outfall.

The problem of water scarcity is already felt in many areas of the country at certain seasons. This problem is aggravated by the deterioration of water quality due to pollution from untreated domestic sewage, industrial wastewater, agricultural run-offs, and urban run-offs. In some highly urbanized areas, high water demand has resulted in over extraction of groundwater and salt water intrusion.

http://adaptationmarketplace.org/data/library-documents/NCCAP_TechDoc.pdf

See ...

Antonio's question was about the long term sustainability of outfalls discharging primary treated wastewater and the discussion. The fact that it is a bad idea is well documented from the many polluted receiving waters experienced with marine life and fishing impacted apart from recreational use. Best management practices including secondary biological treatment of wastewater has remedied and allowed some of the polluted receiving waters to recover. However, the best approach is to eliminate completely any wastewater discharge and reuse the water to recharge our depleted drinking water supplies - coastal cities are finding saltwater intrusion into their once pristine aquifers from over pumping to supply growing populations.

The underlying principle for outfall wastewater discharge is dilution - locate it far enough and let it disperse and get diluted. The calculations I have seen and done have been basically based on the dilution principle. With industrial pretreatment program, it has to be provided if the contaminants  pass through wastewater treatment however advanced as neither the primary or biological process reduces the contaminant to acceptable discharge levels. 

I am not aware that " all biological sewage treatment systems are our way of mimicking natural processes that occurs in our oceans".  A WWTP bioreactor is an artificially man-made processing device which does not occur naturally. Further, the bottom of the ocean is  a desert -not all!! A  shipwreck  especially wooden ones in a barren area provides a carbon source and a few years later the shipwreck is the center of marine life.

The argument that the receiving waters will treat untreated wastewaters naturally is similar to the arguments pushed by industries and corporations who denounce agencies and activists who ask for safeguards from polluting the environment. They scream costs are too high. In the US, many a company has shuttered and transferred their manufacturing bases to countries which do not have environmental safeguards or do not enforce them strictly. I recall an article with photos of an industrial area in China where the receiving waters was polluted heavily with untreated discharges from a number of factories. You can find numerous examples of this disregard in number of countries.

 In the mean time, a number of male fish have been observed to develop female characteristics - they were not mimicking  "Caitlyn" Bruce Jenner (see the notorious Kadarshians). It is claimed that estrogens  in treated wastewater outfall discharges are causing this transgender effect.

Dear Subhash: Many decades ago, wastewater treatment was considered for many people an unnecessary luxury. Wastewater treatment technologies have observed a strong and continuous development in the more recent times. With respect to discharges in water bodies, everything in nature tends to equilibrium, and human activities should not unsettle aggressively such natural equilibrium.

Antonio,  this is the first time I have participated in a question where the author asks the question in order to argue a personal point of view.  I would argue that this is not the venue for such a discussion.  I also do not appreciate your double standard when others criticize my specific comments and you stand by while answering my comments about "not well informed and off base"  which I directed to anonymously to many of the respondents within a few hours.  Since you aren't responding I will.  When he says " A WWTP bioreactor is an artificially man-made processing device which does not occur naturally"  is only true when talking about the reinforced concrete tanks, pipes, pumps and aerators.  I was trying to make the argument that the oxidation of organic carbon by oxygen and indigenous biomass was equivalent between engineered systems and the natural world (i.e. lakes, rivers and oceans).  the only difference I have observed by many years of research, study and data gathering is the rates of reactions.   When he says "The argument that the receiving waters will treat untreated wastewaters naturally is similar to the arguments pushed by industries and corporations who denounce agencies and activists" is basically branding me a holocaust denier.  I take this very seriously.  He should not be flippantly saying stuff like that.  It really is a tool the tobacco lobby and climate change deniers have used to good effect.  I don't consider myself, in the least,  to have very much in common to these groups.

Mohan,  keep practicing, your comment about Jenner and feminization of fish was not really funny and awkward.

I

Dear Mohan and Dear Angus: Thanks very much for your fruitful, positive, and constructive participation in this discussion. Is important to see the several facets of the problem in a positive and constructive way, and you are surely contributing greatly for that. The current legislation and practice indicate predominantly the position supported by Angus, with a rigorous control of the resulting water quality parameters, and, as Angus correctly pointed, is necessary not forget the huge amount of financial resources involved in this problematic. In the dialectic of Hegel neither the thesis nor the antithesis is wrong. Both are fundamental for evolution. I do not deny that I have a clear personal point of view with respect to this subject, but I asked this question in order to learn more, and is what I am trying to do with all participants, and particularly with you both. Thanks again for your participation, kindness and understanding.

The applicability of anaerobic treatment for municipal sewage (mixed sludge and wastewater) depends strongly on the temperature of the sewage. The activity of mesophilic anaerobic bacteria is at its optimum at 35°C. At lower temperatures, bacterial activity decreases, which results in lower treatment performances. This is the reason why in cold climate countries (which are mostly industrialised), only a small separated portion of the sewage, namely the primary (after sedimentation) and secondary sludge (after aeration) are treated anaerobically, however requiring a heavy insulation and heating system, while the bulk of the volume, the wastewater, is treated aerobically mostly with aerators in open or closed ponds.

http://www.sswm.info/sites/default/files/reference_attachments/TBW%202001%20Anaerobic%20methods%20of%20municipal%20wastewater%20treatment_0.pdf

Short answer is NO!

because all contaminants (i.e organic, inorganic & microbial) are still present in HIGH concentration.

Actually there was a recent report last month on male fish becoming female in North Carolina!! See links below and decide why currently treated wastewater outfall discharges are now creating new problems downstream but not upstream:

http://www.wateronline.com/doc/male-fish-north-carolina-rivers-found-have-female-parts-0001?sectionCode=TOC&templateCode=Single&user=3132979&source=nl:43751&utm_source=et_10759433&utm_medium=email&utm_campaign=WOL_2015-09-01&utm_term=87e38578-c2c2-477c-ba3f-234f00553775&utm_content=Male%2bFish%2bIn%2bN.C.%2bFound%2bTo%2bHave%2bFemale%2bParts

http://www.wateronline.com/doc/sex-changing-fish-inspire-new-method-of-wastewater-treatment-0001

http://www.wateronline.com/doc/drugs-slip-through-sewage-plants-into-great-lakes-0001

Dear Mohan: Thanks very much again for your answers. As already noticed, I agree with most of your considerations. In fact it is not likely that fishes are mimicking humans. In optimization, however, is also a fact that humans already mimic some aspects of living communities and particularly fishes. Treatment of wastewater is frequently expensive, and particularly the costs of operation. It is not economically feasible and efficient to treat combined flows when it rains (as we all know, there is a great volumetric disproportion between storm water and sanitary sewer flow). It is difficult to understand so many still existing combined systems, even if the conversion to separate systems can be in some cases relatively costly.

In Southern California, they have been injecting drinking  water to prevent aquifer saltwater intrusion since about 1965 and then highly treated wastewater the last 10 years or so here is one great example of beneficial use. However , the wastewater effluent is treated to a higher level using UV and photolysis. The following two links one from the District  with one from a UV system manufacturer supplying the system gives a good introduction.

http://www.wrd.org/engineering/reports/TB13_Fall07_Seawater_Barriers.pdf

http://vertassets.blob.core.windows.net/download/2ab4d117/2ab4d117-0fdc-44cc-9ee8-2e8bb2159013/los_alamitos__california_leo_j__vander_lans_water_treatment_facility_case_study___environmental_contaminant_treatment.pdf

The presence of drugs and pharmaceuticals in related wastewater is already raising concerns. Links below may be of interest:

 http://www.wateronline.com/doc/dbps-lead-to-water-state-of-emergency-in-canada-0001?sectionCode=NewsFeaturedItem&templateCode=Single&user=3132979&source=nl:43833&utm_source=et_10759433&utm_medium=email&utm_campaign=WOL_2015-09-10&utm_term=87e38578-c2c2-477c-ba3f-234f00553775&utm_content=DBPs%2bLead%2bTo%2bWater%2b%2527State%2bOf%2bEmergency%2527%2bIn%2bCanada

http://www.wateronline.com/doc/ontario-has-record-breaking-level-of-drugs-in-water-0001http://www.wateronline.com/doc/what-wastewater-contaminants-say-about-europe-drug-culture-0001

@ Manuel

Completely all right with your answer

Came across an article (link below) about depleting aquifers and desertification, thus the urgency to reclaim treated wastewater:  

https://www.revealnews.org/article/what-california-can-learn-from-saudi-arabias-water-mystery/

Dear Manuel: You opened somehow a certain kind of Pandora box. The problem is not just the water. There is much water in the planet, particularly salt water. The problem (Pandora box) is the availability of fresh water in many regions of the planet, its quality, and its distribution spatial and temporal. There is excessive water in some places in some moments, causing sometimes huge floods that destroys everything, and absence or scarcity of water in other places, practically continuously, or for a long time. In fact, recharge of superficial reservoirs (lakes) natural or artificial and underground aquifers may attenuate somehow local disequilibrium. In the case of discharge in lakes (at least), wastewater must be subject previously to tertiary treatment with removal of nutrients in order to avoid eutrophication.

Strengthening the construction of sewage supporting pipe networks, will enhance wastewater closure and collection in urban villages, old towns and urban fringe areas. The existing combined drainage system should be transformed into separate drainage systems; if they are difficult to transform, then appropriate actions such as closure, storage and treatment should be taken. 

http://www.ecegp.com/chinese/DataBase/UploadFile/20150511113319501.pdf

Wastewater Treatment and Reuse: Sustainability Options

One of the most promising efforts to stem the global water crisis is industrial and municipal water reclamation and reuse. The WateReuse Association defines reused, recycled, or reclaimed water as “water that is used more than one time before it passes back into the natural water cycle.” Thus, water recycling is the reuse of treated wastewater for beneficial purposes such as agricultural and landscape irrigation, industrial processes, toilet flushing, or replenishing a groundwater basin (referred to as groundwater recharge). Water reuse allows communities to become less dependent on groundwater and surface water sources and can decrease the diversion of water from sensitive ecosystems. Additionally, water reuse may reduce the nutrient loads from wastewater discharges into waterways, thereby reducing and preventing pollution.

http://www.consiliencejournal.org/index.php/consilience/article/viewFile/308/159

Thanks, Dear Subhash, for your answer with an excerpt of the paper entitled “Wastewater Treatment and Reuse: Sustainability Options”, by S. C. Jhansi (Gujarat Research Society’s Pushpa Navnit Shah Centre for Lifelong Learning), M. S. Campus, and S. K. Mishra, published in 2013 in “Consilience: The Journal of Sustainable Development”, 10 (1), pages 1 – 15. I agree in general with the considerations expressed in the good excerpt that you selected. Thank you. Given that I believe you are a good friend and a man intelligent and of good will, allow me challenge you with two questions about your answers in this discussion: Is it possible to have a development that is not sustainable? What do you think about the pictures/figures that you posted in your answer of page 4?

Came across a just published paper studying treated wastewater plant discharges effects after biological treatment implementation. See link below:

http://www.scirp.org/Journal/PaperInformation.aspx?PaperID=60392&utm_campaign=linkedin&utm_medium=zyf

Dear Mohan: Thanks for the pertinent reference that analyses aspects related with the importance of nutrient removal in the Macroinvertebrate Community of a river. Eventual studies of the influence of common pollutants in coastal marine ecosystems would aid certainly this discussion too.

Thanks for your contribution, Dear Lawrence. Wastewater treatment systems in fact observed a great evolution in the last decades, and filtration may be considered one of the components of the treatment processes possibly with increasing importance in some cases. There are marine/submarine outfalls in USA, and this was also one of the reasons for sending/sharing this question with you.

Dear Antonio,

What do you mean on primary treatment of wastewater? What risky pollution elements and in which concentration the treated wastewater does contain? Have you any data on the impact of treated wastewater on marine biodiversity?

Dear All,

I am afraid that long time discharge of wastewater not properly treated might have contributed to the development of marine dead zones.

http://www.vims.edu/research/topics/dead_zones/index.php

 https://en.wikipedia.org/wiki/Dead_zone_(ecology)

http://oceanservice.noaa.gov/facts/deadzone.html

https://en.wikipedia.org/wiki/Wastewater_treatment

Dear Pierlorenzo. Thanks for your answer. Generically, I agree with you. Based on the argument of dilution and self-depuration, historically (?) many discharges were (still are?) performed even with treatments (?) less than the primary. This is particularly pertinent for example, but not only, for the SSO, or CSO.

https://en.wikipedia.org/wiki/Sanitary_sewer_overflow

http://www.ecy.wa.gov/programs/wq/permits/cso.html

Dear András: Thanks for your excellent contributions with issues very important and pertinent. I never researched before specifically in this area of submarine outfalls, so I haven’t specific data on the implications in marine biodiversity. I know what are the generic arguments and the legislation, but the frequently accepted arguments of dilution, rapid death of microorganisms present in the wastewater, and self-depuration, similarly to what happened historically with the interior waters, never convinced me totally. With primary treatment, I meant the typical preliminary treatment (basically screening, and sometimes removing of oils and fats and/or grit/sands) and primary treatment (removing of suspended solids). According to the World Bank Group (first link bellow):

“Primary (mechanical) treatment is designed to remove gross, suspended and floating solids from raw sewage. It includes screening to trap solid objects and sedimentation by gravity to remove suspended solids. This level is sometimes referred to as “mechanical treatment”, although chemicals are often used to accelerate the sedimentation process. Primary treatment can reduce the BOD of the incoming wastewater by 20-30% and the total suspended solids by some 50-60%. Primary treatment is usually the first stage of wastewater treatment. Many advanced wastewater treatment plants in industrialized countries have started with primary treatment, and have then added other treatment stages as wastewater load has grown, as the need for treatment has increased, and as resources have become available.”

http://water.worldbank.org/shw-resource-guide/infrastructure/menu-technical-options/wastewater-treatment

http://www.epi.yale.edu/case-study/primary-vs-secondary-types-wastewater-treatment

https://www.watercare.co.nz/SiteCollectionDocuments/AllPDFs/PDFs%20v2%20111010/Wastewater_treatment_process_3.pdf

The enforcement of the acquis communautaire in the area of urban waste water collection and treatment refers to the implementation of the provisions of the local Council concerning urban waste water treatment and to the EU common positions on the negotiating positions in the environmental area

http://www.themedpartnership.org/med/documents/library/background-documents/naps/en/attachments%7Cattachments%3A017%7Cfile

In the recent years many software are being used to estimate the effect of wastewater discharge into marine environment. Normally, these software models the concentration of BOD or even those of N and P. Such simple modeling can lead to environmental disasters as there are many dangerous substances are that being poured into the municipal wastewater system by households. I, totally, disagree with any dilution business since we have to keep environment alive for our next generations. Primary treatment of municipal wastewater include separation for removal of some large particles and it has nothing to do with harmful substances. The wastewater is valuable in many countries as a new source of water if it is well treated. Or, at least it can be used as a good source of water in agricultural activities if treated accordingly. Man is not only discharging wastewater into the environment of marine organisms but also dumping residential waste over there too. Marine environment should not be considered as garbage area in any way. 

Thanks for sharing. I am not specialist in this field and the question is a good chance for me to start learning about this very interesting topic. The information obtained by the colleagues through their answers is valuable.

Regards

Thanks for your answer and for your interest in this subject, Dear Aristidis. Greece has lengthy costal lines and many Islands. Environment is one of your areas of expertise. I predicted that this question could be of your interest, even if I do not know exactly what the situation in your country is with respect to the coastal ecosystems. A quick search conducted me to the links below

http://www.oecd.org/env/country-reviews/2448632.pdf

http://biodiversity.ru/coastlearn/tourism-eng/why_problems.html

http://www.sciencedirect.com/science/article/pii/0160412093900905

http://link.springer.com/article/10.1007/BF01701704

Dear Prof. Diogo,

Thank you for your response. You are right. As you wrote, environment is one of my areas of expertise. But, actually, I have not worked with wastewater, as it can be seen in my 'Info' section, among others. Thus, I chose not to risk an answer to the question, based on the others knowledge. Nevertheless, as I have already written, the question (including the subsequent discussion thread) offers me a good opportunity to be informed about this interesting topic.

Regards

Thanks for your kind participation showing intelligence Dear Aristidis. Perhaps sometimes we can … or we may try to travel a little outside from our area of comfort. Sometimes the best thoughts come exactly from where we expect less, if we follow the correct attitude, as you did. I agree with Thomas A. Edison when he said (see the link below): “If we did all the things we are capable of, we would literally astound ourselves”.

http://www.brainyquote.com/quotes/quotes/t/thomasaed161979.html

Dear Prof. Diogo,

Thank you for your kind response. I feel that sometimes, one step at a time, is better than 'many steps'.

Regards

I do not think so.

Primary treatment does not seems enough for that type of water management.

It is not sufficient.

Wastewater should be treated sufficiently to be reused as drinking water.

We find pharmaceuticals in drinking water. Why? Because treated wastewater is not well treated even if for agriculture use.

The level of treating wastewater should be revised and elevated to drinking water use.

Best wishes,

P.S. More information may be read here:

Article Increasing Trends Towards Drinking Water Reclamation from Tr...

Dear AMAFD.

Having done many natural wwtp can deal with this concept for a solution. 1stly only ww of municipal nature ie house hold communities / urban nature may be evolved and no industrial ww to be clubbed.

The treatment is suggested done in 5 phases:

Pre process stage with 5-10% hrt say 500 BOD to 450 ppm..

to be contd.

In continuation :

5 stages.

1. Pre process 5-10% hrt

2. Primary 30% hrt

3. Secondary 30% hrt

4. Tertiary 30% hrt

5. Finishng and polishing.5-10% hrt.

Process given is natural process ie

Anaerobic septic tank with roof with man hole opngs and surface lined with greens grass Etc..

2. === // === with coarse stone filters

3. == // === with small pebbles..

4. Aerobic with phyto plants ..

5. Anerobic - closed tank for storing effluent / outlet water for re use.

Therefore the primary stage being important can have upto 60 - 70 % hrt and then released in large dugout at low tidal sea time.

Then when tide increases water level dilution and remediation occurs for remaining 30% too is taken care off.

Can introduce floats with plants for more remediation.

HRT given is 6 to 8 days..

ie if daily flow is 100 kl BOD 500ppm

Contd..

100kl x 8 days is 800kl / cbm

Have primary process for 560 -600 kl cbm septic tk.

At outfall have large dugout say 300kl cbm for 30% process with floats with phyto-r remediation.

Will share a design plan of an urban drain at East of The Taj area off Agra city UP India.

Well wishes ..

in turkey coast with the help of deep sea discharge sewage and rainwater is discharged to the Black Sea. Very simple primary treatment is applied before discharge but no chlorination is performed. In this way, as a result of the primary treatment of deep sea discharges in seawater was seen in the research is not appropriate.

Hi. OU.

It is fair to know capacity of process ie kl per day..

conveyance pipe too provides Anerobic treatment assess d x l cbm flow in a day.

Well wishes.

Have a nice day,

The wastewater of 350000 people is given to your Black Sea with deep sea discharge. This makes approximately 70,000 m3. This amount is directly poured into your Black Sea after a very simple pre-treatment. No flow measurement is made in the facilities. Many greetings.

Researcher @OU, indicated that 350000 people released x200l ie 70000kl/cbm- 70ML into Black Sea.

(At a region a few km coastal length by land expanse width a few hundred metres.)

The facilties of ww conveyance from urban habitat to open sea- coast provides ww treatment process as detailed below :

1. It could be thro a long conveyance pipeline- providing anaerobic process in transit.

2. Release of gases will be duly taken care off, (vented) at some locations in long pipe.... km by ... bore m, flow velocity metre per second Etc.

can estimate volumetric containment in cbm kl .

3. Then release of water could be into a zone having large dugout or cavity providing the final process.

- approximate cubic content kept estimated for assessment.

4. This release of effluent, also could go thro dilution with larger waters from mid-sea region due to fall and rise of tide- considered as flushing and replacemnt of fresh sea water.

5. Of and on action of waves with on rush of water onto coasts could provide extended aeration, felt by vapours and gases released and interspersed with fresh land and sea breezes at the coastal region.

I would request @OU to endorse the notings of the process account as given in steps Nos 1 to 5. Please.

It could be possible that the efficacy of this ww process may be more than adequate and the bio diversity assets are not affected.

Be it be solid or liquid wastes, seas are used as " waste -sink ", world over.

These practices need to be clubbed with remedials for protection of environmental resources.

With well wishes.

Good day,

Thank you for your questions and contributions.

My answers: There is a very simple pre-expansion system after the application of deep-sea outflow. Answers to the articles you write:

For 1) The maximum residence time of the waste water in the pipes is between t = 20 and 30 minutes. Long residence times lead to a deterioration of the wastewater. In other ways, gas formation (CO2, CH4) occurs by facultative or anaerobic digestion.

For 2) Control chimneys are placed in the sewer system at certain intervals. Gas dispensing is allowed.

For 3 and 4) In the case of deep-sea discharge, T90 (dilution) is taken into account taking into account the waste water and the seawater meeting.

For 5) The application of the measures to be taken in the pipe systems for the formation of odors is almost non-existent. It's like suggesting the cleansing of the smell. If the wastewater treatment is not carried out, who will then clean the smell?

Many Thanks

Work for a clean world!

Thanks Dears Djamel, Ajit, and Osman, for your answers, serene participation, and for keeping this discussion alive, with diverse positions about the best way how to deal with this subject. Particularly answers related with examples, studies or experiences of marine/submarine outfalls, all over the world, as the example shared by Osman, should be naturally encouraged.

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/marine-outfall

Dear Dr Chuck A Arize and others,

Submarine outfall done with deep ponding process is advantageous and compliance to PCB standards

Can be done .. Well wishes..

António Manuel Abreu Freire Diogo

Answer to your question, is the old methods, in the past millennium how people has system and methods in place.

Bogs were there, mire was everywhere in every regions for oil items discarding. Boats and ships yards had brooks near by. Word is pond. Not lakes because lakes are for water flow from the rivers .

Regards

Fatema Miah

Highly treated waste-water effluent from municipal waste-water treatment plants can be reused as a reliable source of water for agricultural irrigation, landscape irrigation, industrial recycling1.

The use of long-term marine/submarine outfalls for municipal wastewater after only primary treatment has both advantages and disadvantages in terms of environmental sustainability. It is important to assess the appropriateness of this approach on a site-specific basis, taking into account local environmental, technical, social, and economic factors.