I would suggest areas for investigation should focus on reducing energy. Firstly further development of a simple, low cost, easy to maintain “fit for purpose” technology for small and remote rural communities eg Imhoff tanks, oxidation ponds, biological trickling filters which have very low energy requirements. Secondly, reduce the power (and greenhouse gas emissions) from large urban sewage treatment plants – disconnect the nexus between higher effluent quality = higher energy consumption. It is economic to generate power from anaerobic sludge digestion at plants serving an EP of 50,000 (conventional treatment) and BNR plants serving an EP of 75,000 but there is potential to significantly improve digester efficiency by pre-thickening and effective mixing. Finally sludge drying and beneficial use of biosolids. Biosolids contain nitrogen, phosphorus, calcium, potassium and trace elements beneficial to plant growth. Biosolids also improve the structure and water retention properties of soil. Many Australian soils are deficient in phosphorus. CSIRO (2008) have estimated the intrinsic value of biosolids to be around $66 per Dry Tonne and rising as world-wide supplies of phosphorus decline and supply pressures increase. Provided that heavy metals and toxic organics can be controlled at source, well managed application of biosolids to agricultural land is the most economical and best environmental alternative. Australia has some of most stringent guidelines in the world but still applies approximately 55% of biosolids to agricultural land (AWA management of Biosolids in Australia, 2012) - 170,000 DT/annum directly to farms with a further 30,000 DT/annum composted. On-site solar drying can be used to reduce the sludge volume with a significant reduction in transport costs and associated greenhouse gas emissions. Solar driers can reduce biosolids volumes by 35% to 70% (typical dry solids content is 50% DS).

There are a variety of processes that can be used to clean up wastewaters depending on the type and extent of contamination. Most wastewater is treated in industrial-scale wastewater treatment plants (WWTPs) which may include physical, chemical and biological treatment processes.www.oilgae.com/algae/cult/sew/new/​new.html

In my opinion, the key step of wastewater treatment is the biological process involved. So most of the research most emphasize this aspect

We can clean water for organic pollution, nitrogen and phosphorus without net energy consumption due to the biogas production.

The next demand from society is to recover the nitrogen and phosphorus effectively and to remove micro-pollutants from the water without high energy costs.

For me, its development of affordable & reliable technique for defluoridation of water on mass scale... Yes, there are literally thousands of papers on hundreds of adsorbents, but most of them are impractical..

Fluoride is a drinking water problem. Not a wastewater treatment issue.

I would suggest areas for investigation should focus on reducing energy. Firstly further development of a simple, low cost, easy to maintain “fit for purpose” technology for small and remote rural communities eg Imhoff tanks, oxidation ponds, biological trickling filters which have very low energy requirements. Secondly, reduce the power (and greenhouse gas emissions) from large urban sewage treatment plants – disconnect the nexus between higher effluent quality = higher energy consumption. It is economic to generate power from anaerobic sludge digestion at plants serving an EP of 50,000 (conventional treatment) and BNR plants serving an EP of 75,000 but there is potential to significantly improve digester efficiency by pre-thickening and effective mixing. Finally sludge drying and beneficial use of biosolids. Biosolids contain nitrogen, phosphorus, calcium, potassium and trace elements beneficial to plant growth. Biosolids also improve the structure and water retention properties of soil. Many Australian soils are deficient in phosphorus. CSIRO (2008) have estimated the intrinsic value of biosolids to be around $66 per Dry Tonne and rising as world-wide supplies of phosphorus decline and supply pressures increase. Provided that heavy metals and toxic organics can be controlled at source, well managed application of biosolids to agricultural land is the most economical and best environmental alternative. Australia has some of most stringent guidelines in the world but still applies approximately 55% of biosolids to agricultural land (AWA management of Biosolids in Australia, 2012) - 170,000 DT/annum directly to farms with a further 30,000 DT/annum composted. On-site solar drying can be used to reduce the sludge volume with a significant reduction in transport costs and associated greenhouse gas emissions. Solar driers can reduce biosolids volumes by 35% to 70% (typical dry solids content is 50% DS).

I would suggest areas for investigation should focus on reducing energy. Firstly further development of a simple, low cost, easy to maintain “fit for purpose” technology for small and remote rural communities eg Imhoff tanks, oxidation ponds, biological trickling filters which have very low energy requirements. Secondly, reduce the power (and greenhouse gas emissions) from large urban sewage treatment plants – disconnect the nexus between higher effluent quality = higher energy consumption. It is economic to generate power from anaerobic sludge digestion at plants serving an EP of 50,000 (conventional treatment) and BNR plants serving an EP of 75,000 but there is potential to significantly improve digester efficiency by pre-thickening and effective mixing. Finally sludge drying and beneficial use of biosolids. Biosolids contain nitrogen, phosphorus, calcium, potassium and trace elements beneficial to plant growth. Biosolids also improve the structure and water retention properties of soil. Many Australian soils are deficient in phosphorus. CSIRO (2008) have estimated the intrinsic value of biosolids to be around $66 per Dry Tonne and rising as world-wide supplies of phosphorus decline and supply pressures increase. Provided that heavy metals and toxic organics can be controlled at source, well managed application of biosolids to agricultural land is the most economical and best environmental alternative. Australia has some of most stringent guidelines in the world but still applies approximately 55% of biosolids to agricultural land (AWA management of Biosolids in Australia, 2012) - 170,000 DT/annum directly to farms with a further 30,000 DT/annum composted. On-site solar drying can be used to reduce the sludge volume with a significant reduction in transport costs and associated greenhouse gas emissions. Solar driers can reduce biosolids volumes by 35% to 70% (typical dry solids content is 50% DS).

Simultaneous biological treatment of wastewater by microalgae, bacteria in aerobic, anaerobic , dark/light via heterotrophic and autotrophic growth mode will be effective strategy

Simultaneous biological treatment of wastewater by microalgae, bacteria in aerobic, anaerobic , dark/light via heterotrophic and autotrophic growth mode will be effective strategy

Simultaneous biological treatment of wastewater by microalgae, bacteria in aerobic, anaerobic , dark/light via heterotrophic and autotrophic growth mode will be effective strategy

wastewater will be increasingly re-used with membrane processes, which would lead to an elevated level of salinity. The reduction of low salinity would be one of interesting topics.

what I feel most important is to increase reuse potential of wastewater as water is becoming scarce and water is becoming polluted day by day. Therefore, there needs cheap and reliable treatment methods so that wastewater could be safely used. Dangerous contaminants (heavy metals, harmful microbes) in water could be removed upto a safer level.

Membrane Based WWTT processes especially :

(a) reduction of volume of waste water followed by MBR treatment and retention of nutrients in the waster water.

(b) Extraction of fresh water from waste water into a draw solution that has higher osmotic pressure (Forward Osmosis process)

(c) Fresh water reclamation from industrial/treated domestic waste water using Membrane Distillation

(d) Simultaneous desalination, energy production and waste water treatment using microbial fuel cells (3 in 1 process)

New sorbent materials or smart sorbent materials that can be used as universal adsorbent materials

thanks for your valuable comments.

i haw a question about the computational fluid dynamics application in waste water treatment (especially pulp and paper waste).

What do you think is the most urgent research topic in CFD simulation of the pulp &paper wastewater treatment (or equipments)?

i want to choose a topic for my phd thesis.

what is the interest case study in CFD simulation of pulp and paper waste treatment? (fluidized bed bio-reactor? clarifier? filters? ....)

can you propose me a topic?

thanks in advance.

Biofilm-based techniques have been widely used for a long time. What is the biological mechanism for this techniques? Do you know any mechanistic studies in this area? To design and improve the current wastewater treatment technology, it is important to understand the mechanisms by which the process take place.

removing some hazardous materials such as Arsenic from wastewater by magnetic nanoparticles is a very important research topic. In fact, i think finding some bio-compatible materials for coating magnetic nanoparticles is the best topic nowadays.

@Solmaz, actually, it has still been a debate what material is really bio-compatible. Gold- and silver-nanoparticles are less toxic than oxidized metal nanoparticles because the latter, under certain conditions, has potential to generate oxidized free radicals in cells that may cause damage. But they are only "less" toxic.

@Solmaz

thank you for your advice. my interest field is CFD simulation. on the other hand the pulp and paper waste water does not contain Arsenic.

the fluidized bed bio-reactor or ozonation reactor may be better choice for my study.

Additionally to the improvement of the technologies that have been made by many experts worldwide, I believe that an important issue is to drive the concept of wastewater treatment (in particular organic wastewater) to resource recovery in a view of biorefinery concept. A 3rd generation treatment will bring us a paradigm shift by adding value to pollutants. Many efforts have been made on that sense like the production of biofuels or biopolymers.

I think the xenobiotics which are related to small amount of pharmaceutical and drug residuals in water and wastewater have significant effect on water quality in future.

I recommend membrane bioreactor, microbial fuel cell and biofilm-based techniques

I believe 2 noteworthy topics at the forefront of wastewater treatment research are improving the reuse of both domestic and industrial wastewaters as well as the improved treatment, reuse and disposal of sludge.

In terms of chemical treatment - you can check this articles:

Article Wastewater treatment by means of Advanced Oxidation Processe...

Article Wastewater treatment by means of advanced oxidation processe...

best regards,

GB

The suggestion by B. Mahabir is also an excellent and urgent area of current research.

https://www.epa.gov/sites/production/files/2015-08/documents/wastewater-guide.pdf

Effective photocatalytic wastewater treatment using semiconductor metal oxides is a great research topic.

Along with what Dr Silva mentioned above, the decentralisation and increasing the reuse potential of wastewater/water treatment. Mitigating the huge amounts of energy used pumping water and wastewater across major cities to end users and centralised wastewater treatment plants, along with reducing the massive issues today facing all municipalities regarding the maintenance of ageing infrastructure are two drivers that come to mind.

The urban model for electricity supply is gradually becoming decentralised with the advent of cost effective home/town battery and renewable technologies. The water industry should be focusing on doing the same.

Use of immobilized microbial cells in wastewater treatment can be a good option. As well as the phytorid technology can work for 24 hours without electricity and emission of toxic components .