I am interested in evaluating the economic technical and environmental efficiency of using constructed wetlands for oily wastewater treatment. Can someone with field experience advise on the viability of this research and possible directions to explore for gap identification and preferring of workable solutions?
We are using constructed wetlands many years for produced water treatment, i.e., water contaminated with hydrocarbons from the oil and gas exploration. You can find information on this project online (search for Nimr Water Treatment Plant, e.g., https://www.omanspire.om/articledetails.php?articleid=120&id=10, https://www.bauer.de/export/shared/documents/pdf/bre/project_sheets/bre_nimrpaper_en.pdf).
There is also a book chapter with detailed info and description " Integrated Produced Water Management in a Desert Oilfield Using Wetland Technology and Innovative Reuse Practices " in the book "Constructed Wetlands for Industrial Wastewater Treatment" published recently by Wiley.
Bassey Okon Bassey : I am not sure, that constructed wetlands are the best solution for elimination of oil and grease. The reason is that solubility in water of both (oil and grease) is very low. If the pollutant is not dissolved in water, it could be hardly treated by constructed wetlands. Some physical separation should be included in the system.
Another problem with application of contructed wetlands for treatment of oily wastewater is, that degradation (biodegradation) of oil pollutants is the best under aerobic conditions. In the case of constructed wetllands the bottom part of the root beds is commonly anaerobic.
Regards
Vit
Dear Okon,
constructed wetland is not a good
solution to remove Oil and grease comming from petroleum industry.
Because removel process is very slow by natural bacteria.
However, It is successful for the oils of natural products (coconut & animal etc.).Bacteria can degrade them rapidly because of their unsaturated nature and functional groups
Piyal Aravinna
Well, based on my experience it will not at all be effective towards oil and grease removal from wastewater. You can try the same with skimming tank. The efficiency of wetlands are pretty less and only can be used in the case of moderately concentrated domestic wastewater.
Dear Okon,
As mentiond by Atun, if you can add skimming tank (prior to direct wastewater to the construction wetland,) to you treatment system, you can avoid the issues of oil.
Piyal Aravinna
Dear Colleagues
Thank you for your replies and please keep them coming. Can someone share some field data and case studies where CWs were used for oily WWT?
Dear B O B.
As indicated by you, it is desired to separate oil and grease. It is best done at the start as a pre process phase. Being less dense than water it is best removed by physical process by grease trap and or surface-"skimmng method.It is explained in the Bible of WWT.. Metcalfe & Eddy Book.
If the flow rate is high, there could be some carry forward to the 1st phase of WWT Plant.
You would be aware of the % of oily / greas effluent in the total flow. Accordingly the chambers are planned and designed.
Just for an example if you have a ww effluent from a resort. It would have ww from toilets. Wash rooms. Kitchen etc..
It is best not to decant old used cooking oil and greasy residues in the ww effluent stream but removed separately and segregated.
However in dish-wash stream this oily residues would come. This is to be dealt with separately.
Well wishes.
Ajit Seshadri.
Yes , oil and grease contaminants can easily be separated or up-taken by aquatic plants- through Hybrid constructed wetlands . Dr. Muhammad Masood Aslam , from Pakistan , has his PhD thesis on removal of oil and grease from drinking water . Further information , on the subject , can be shared if required .
Dear Islam
Thanks for this. I will like more information on the subject. If you could send me some material by email.
Bassey
An oil & Grease separator and skimming tank are best. Constructed wetlands can be used an an effective polishing treatment for O&G. Emergent macrophytes such as phragmites communis (austrailis) and typhi latifolia for fresh water or Spartina genus for brine or salt water are effective in trapping and eventual uptake of O&G and heavy metals associated with the waste.
Researcher B O B :
Agreeing to @ Dr. Peter Zemek for his guidance.
I have a Research Paper on the subject of Decentralised Waste water system for reuse.
Pl refer to it for details .
Ideally phyto remediation ie using plants which you have referred to comes in the last stage of the treatment.
Well wishes .
hello,
i just finish 2 years study of the treatment efficiency of olive mill wastewater using constructed wetland (phragmites australis).
i can tell you that for naturel effluent like this one the system could be very efficient if we know how to handle it. however, regarding industriel effluent such as petrolium or some other effluent CW could not be efficient as the oil will be hardly degraded and it will deposit on the upper layer of the system which can cause sevral problems as asphyxia or system clogging.
Hello Ayoub
Could you kindly share the results of your work on olive mill WWT?
hello.
You can check my poster on my profile. The paper is under publication. I will share all data once publishes
Hello BAssey,
I agree with other collegues in terms of:
1- Petrol-originated oils are not treatable by CW and in general by classic biological processes.
2- A physical remouval through skimming tank is a good alternative.
However, the skimming tank demands constant manual remouval of the fat accummulation.
Another alternative is to use an anaerobic tank before the CW, as organic oils and fats are efficiently remomed in an anaerobic environment. You just need a tank (that could be a skimming tank) with no ventilation (hermetic), with at least one day of HRT (hidraulic retention time).
Cheers
Alfredo
Dear B O B.
Pl refer to this paper for practical details.
Well wishes.
Prof Ajit Seshadri.
Dear B O B ..
Pl free to be in touch on Dewats wwt plants and its working.
Have been implementing Dewats process, in varied capacities 500 lit per day to 80 kl per day .. all community ww mostly sewage and sullage from communities, 2 decades.
Only a few with industrial ww ..
Well wishes for a New year in 2019.
Prof Ajit Seshadri.
Vels University. Chennai INDIA.
Dear Bassey,
For the selection of an appropriate Waste Water Treatment Technology (WWTT), a researcher or an engineer has to consider the quantity and composition of wastewater, sources of wastewater (domestic or industrial origin), treatment efficiency, objective, requirements, cost, land availability, length of trunk sewer, point of disposal, resource recovery or reuse, environmental impact, social aspect, O & M cost, skill human resources availability etc.
I am sharing to you my three decades professional engineering, academic knowledge, skills and experiences gain from water industry.
Provision of primary treatment such as screening, oil and grease separator through traps, skimming tanks, grit removal should be made at any Wastewater Treatment Plant design.
Depending upon the hydraulic and organic loading, composition such as BOD, COD, SS, NO2, NO3, PO4 and other significant parameters, an appropriate WWTT has to be selected. The Constructed Wet Land (horizontal flow or vertical Flow or both) is mainly used for nutrient removal (Nitrogen and Phosphorous related matters) from wastewater.
Any wastewater contains some amount of oil and grease but it depend on the nature of the industry. I recommend you not use CWL for oil and grease separator and use special skimming and trap mechanism for industrial effluent. After neutralization, other WWTT (more 30) could be use considering the above mentioned factors or aspects.
Regards,
Dr. Chet
Hi Bassey,
Aerobic bio-oxidation of petroleum by microbes is a useful way to degrade the various components, since petroleum is a natural product. I agree with the other comments that a standard constructed wetland is not the way to go, but a manufactured wetland, like my companies MRU bioreactors, are designed to degrade a host of pollutants across the reduction/oxidation ladder. The key is atmospheric O2 and nutrient availability for the methanotrophs to do their thing, you're already providing the carbon source.
We have potential projects for organic and petroleum based oils going in over the next few months and I'd be happy to share the results as they come out. For more info, check out www.ecoislandsllc.com. We work primarily in acid mine drainage reclamation, but the same units can be used for a huge array of wetland environments. Good luck! Colin
Hi Bassey,
These references may be of use to you:
- http://greenspace-alliance.ca/index.php/readings/constructed-wetlands-references/
- http://greenspace-alliance.ca/index.php/readings/a-framework-for-the-practical-science-necessary-to-restore-ecosystems/
Regards,
Dear Researcher- Bassey Okon Bassey ,
Your question as given a month ago, stands as :
Are Constructed Wetlands effective for meeting Oil and Grease Removal consents?
Your additional points given are as below: I am interested in evaluating the economic technical and environmental efficiency of using constructed wetlands for oily wastewater treatment. Can someone with field experience advise on the viability of this research and possible directions to explore for gap identification and preferring of workable solutions?
What we would desire now, please: It would be in order for all to know what you have absorbed from all our notings and give your detailed inference and compilation for our benefit.
This gesture, will be really appreciated, please.
with well wishes,
Prof. Ajit Seshadri .
There are multiple papers from the Society of Petroleum Engineers on the use of wetlands for use in the oil & gas industry, such as SPE 61180, SPE 66522, SPE 84587, SPE 88667, SPE 120257, SPE 94329, SPE 98548, SPE 98567, and SPE 145797
We are using constructed wetlands many years for produced water treatment, i.e., water contaminated with hydrocarbons from the oil and gas exploration. You can find information on this project online (search for Nimr Water Treatment Plant, e.g., https://www.omanspire.om/articledetails.php?articleid=120&id=10, https://www.bauer.de/export/shared/documents/pdf/bre/project_sheets/bre_nimrpaper_en.pdf).
There is also a book chapter with detailed info and description " Integrated Produced Water Management in a Desert Oilfield Using Wetland Technology and Innovative Reuse Practices " in the book "Constructed Wetlands for Industrial Wastewater Treatment" published recently by Wiley.
Dear Prof Seshadri
Thank you for your comments. I am still reading up the subject and reviewing the literature. I will report my progress as the work evolves.
Best regards.
Bassey Bassey
Good question and interesting responses and contributions by each contributor,
Dear Bassey
Oil and Grease removal through constructed wetland is much depended on quantity of O&G. If its level are too much above limits the best thing is go with primary treatment like O&G chamber, other wise hypoxia can takes place or anaerobic condition can be form in CWs (Construed Wetland system). In that condition the reduced zone and anoxic zone can affected . Its also depend on filter media. Oils can affects the rhizome network and substratum. so its best go with SSFCWs ( Sub surface Flow Constructed Wetland system).
Dissolved-phase petroleum hydrocarbons are readily biodegradable, and the degradation rate kinetics are more or less proportional to the molecule length (lower C count = faster k rate). Degradation is roughly 10X faster under aerobic conditions vs. anaerobic conditions, so some designs rely on mechanical aeration to ensure the oxygen transfer is sufficient to aerobically degrade the applied oxygen demand.
Most real-world constructed wetlands experience some degree of free product (oil) entering the system. This provides an additional mass load that will gradually biodegrade and dissolve into the water column (keeping the dissolved-phase concentrations near saturation), so measuring k-rates when a system has been "oiled" is difficult.
Dimensioning the system system to handle the anticipated mass load of free product is a more robust way to address full-scale designs.
Also, many TPH compounds are nutrient-deficient, so checking the NPK demands based on anticipated microbial yields is always a good idea.
Factors like sandstorms and the overall size of the system can also affect the type of system chosen (surface flow vs. subsurface flow).
Yes, but should be check the concentration of hydrocarbon per litre. If its more than 1 gm/litre, might be kill or harmful the plants.
Dear Researchers.
In a community wwt plant, one of our phyto-r beds having cayhna - indica sp, We have noted that a layer oily slick gets on the top layer of soil bed and stays on.
This oil slick is from the kitchen wash water. As remedial solution have resorted to using more hot-water and oil type cleaning liqid sparigly for kitchen wash water.
Chemical type detergents are not used in bathing. washing clothes and in kitchen with water.
Hence the waste water being bio - oriented gets remedied easily.
Well wishes .
Thanks for the insights, Prof Seshadri. I am actually interested in crude oil contaminated wastewater from oil production and processing facilities in rural areas where such assets are usually located.
Dear BOB.
In merchant ships oil gets admixed in water and they use a 3 stage oily water separator getting water upto a purity with oil content in water to be within 15 ppm level.
This water is allowed to be discharged to sea.
You may source information on this device used on cargo ships.
Well wishes.
Dear BOB.
Pl share with me the exact nature of problem -
"is it oil on water surface to be remedied"
As I am a Marine Chief Engineer can visualise the occurence of oil layers on water.
And can suggest do able solutions for retrieving oil from water surface if in abundance or in less quantity,
then oil retrieved can be taken for re use .
Pl send me some site pics and
data..
how much oil in cbm/ kl in
quantity of waste water in cbm / kl.
Well wishes.
- Badges
- Science topic