Domestic Wastewater Treatment

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Domestic Wastewater Treatment

How do I figure out the most suitable treatment process (activate sludge, trickling filter) according to the composition of the domestic wastewater?

Is there a practical tool to determine it?

Is it necessary to particularly focus on nutrients (P and N)?

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28 Answers

  1. we have to stop using chemicals to treat our waste water.  there are better and greener technologies that can treat nutrients.  and even recover nutrients .    many options out there.  

  2. we have to stop using chemicals to treat our waste water.  there are better and greener technologies that can treat nutrients.  and even recover nutrients .    many options out there.  

  3. All process are good technology, the most thing is Ferric Chloride to remove P, while N can be remove through process PST, Filtration, humus tanks.

    Thank you,

    Mangena P

  4. All process are good technology, the most thing is Ferric Chloride to remove P, while N can be remove through process PST, Filtration, humus tanks.

    Thank you,

    Mangena P

  5. Milk processing,paper mill and pharmaceutical are waste streams typically treated by trickling filters.

    Discharge quality requirements are getting tighter and land is getting costlier,and there's a greater case for an additional premium on activated sludge,making it perhaps getting graded down via a vis trickling filters,membrane bioreactors

  7. Hello Lara

    Activation of sludge deserves two responses

    Activation: a function that has nothing to do with the problem of sludge. It serves only to defuse the methanization activation of the medium. At the very beginning the concrete tanks were cracking, the concrete disintegrated under the effect of the putrefaction of the medium. The rotating arm removes the effect of strong metanization

    Mud

    In biology, mud is the ultimate stage of destructuring of organic matter. The only natural tool that eliminates mud is putrefaction. Incompatible with the action of aeration

  8. hello Lara.  yes there is a practical tool.   use Net Present Value.  at the end of the day, the lowest total cost over 30 years is best.  its waste water.   Capital cost, yearly repair and maintenance cost and daily operating cost including everything that affects your EIA.  air quality, noise pollution and discharges.  

     

    as for N and P, you live in the EU and thats part of the local requirements.  

     

    have fun

  10. the main process is aerobic biological treatment, the sludge needs to be furthur digested and turn into a furtilaizer, be aware to hormones and medication in the waste stream , also fats can ruin the procees.

  11. Hi all! I added a file with the characterization of the wastewater of 3 different points of the drainage network and the discharge limits by law. The points 2 and 3 are on highly obstructed areas, so maybe not that representative. The treated wastewater will be discharged on a river, and is close to reach the ocean. The land is abou 6000 m2 and te wastewater is tottaly domestic, urban. I think that will be important to remove N from my evalluation, will it be better an oxidation ditch or anoxic/aerated tank? Thank you all for your feedback!

  12. Dear Lara,

    The choice of ​treatment ​process depends ​upon the volume ​to be treated, ​available space, ​ costs of ​construction ​and quality of ​the discharge ​required. ​- it depends on ​the price/​availability of ​land. If there is ​insufficient ​land for ​activated ​sludge, or if ​the discharge ​quality ​requirements ​are so tight ​that it makes ​economic sense, ​processes like ​membrane ​bioreactors are ​used, but at ​the expense of ​higher capital ​and operating ​costs. ​

     

    Some cheaper operations are following ​

    1. Trickling Filters,
    2. RBC

    Activated ​sludge is also ​better if there ​is a requirement ​to remove ​nitrogen from ​the wastewater, ​since trickling ​filters can'​t provide the ​anoxic ​conditions ​needed to ​remove nitrates.​ Constructed wetlands are treatment systems that use natural processes involving wetland vegetation, soils, and their associated microbial assemblages to improve water quality. These systems can be used commercially for efficient biological treatment of wastewater, and it will also act as a better eco-friendly method when compared with other conventional treatment methods. Natural wetlands, marshes, swamps, and bogs play an important role in protecting water quality. Constructed or artificial wetland systems mimic the treatment that occurs in natural wetlands by relying on plants and a combination of naturally occurring biological, chemical, and physical processes to remove pollutants from the water. Because constructed wetland systems are designed specifically for wastewater treatment, they typically work more efficiently than natural wetlands. Some constructed wetland system designs can closely resemble natural wetlands enough to provide additional habitat areas for many birds, animals, and insects that thrive in wetland environments.

    Regards,

    Prem Baboo

  13. I'm not aware of a particular tool and nutrients are important.  You have to start in reverse.  You have to know what are the discharge limits you are allowed to discharge at and is it based on an absolute or a centile discharge.  Once that has been established, you have to establish the space, which is available, the capital and the peak flows, which your plant is able to deal with.  The nutrient level could also be misleading because the nitrogen needs to be split into ammonia nitrogen and total nitrogen, which is the ammonia nitrogen and other nitrogen and is the phosphate in a combined form or free phosphate.  The other main question is what is the source of your effluent?  A simple plant for a hotel or housing estate could be different from a plant with industrial or food wastes.  Once that has been done, then you can start talking to specialist designers of effluent plants.  So the COD or BOD of the waste will need to be known.  Another need to know is whether there is a fat oil & grease (FOG) content.  

    The basic principles are screening first then look at other processes.

  15. As per Gareth's comment below, footprint is a major factor in selection of a technology. If you have land available then the low OPEX cost of a constructed wetland and reed bed system will work in developing countries with limited energy to power conventional MBBR or SBR designs. Engineered wetlands (wastewater) and reed bed (sludge) provide an ideal solution where pristine effluent is desired and a biosolids is created that has beneficial reuse for agricultural activities.

  16. Hi Lara! After determining the influent characteristics, you have to determine the foorprint for the design. In our case, some places here have small foorprint and would be impossible to employ a full SBR technology. We usually employ MBR. If the waste is combination of domestic and septic, you might want to have an oil separation process then ABR (Anaerobic Baffled Reactor) or Anoxic, then equalization lastly MBR. If high COD, employ a clarification system before the biological process

  17. If you sufficient land that is inexpensive enough, another great option is land treatment.  Google Muskegon County Wastewater Management System for details of a 40 MGD plant in Western Michigan, US.

  18. Hire a consulting engineer who specializes in wastewater treatment. Most  domestic  plants are activated  sludge, but  circumstances ( size, location , availability of  raw  materials , effluent  requirements, existing  facilities, local  costs  etc) could dictate other  choices. MOP 8 published  by WEF discusses  options. N & P  are  normally important  only if  effluent  requirements  include them.

  21. When you say "domestic" if you are referring to residential (or office complex) the answer is 1. Bio Digester. 2. microbial species RNA (not DNA) Archaea. 3. Your choice of discharge options.  To be energy efficient connect this device to a bio generator.  During the "BIOREMEDIATION " process as sludge organic compounds are being reduced to their elemental/nutritional state they release electrons which can be collected and used and connected to your residential electric grid.   Not in wide use. But it is an answer to your question.

  23. For every single system I’ve ever designed (20+ systems) I agree 100% with the last poster that it depends on the experience of the engineer. There is no “one size fits all” solution that will solve your problem (man do i wish there was!!!).  The very basics are building blocks and foundation to a successful solution which are:

    - budget (if there was never a budget issue I would almost always choose a Bioalc or some type of biological nutritent removal system...but they can be covert costly....even an old technology like an oxidation ditch is incredibly efficient at reducing the regulated parameters....at least where I live)

    - is the treated effluent going to be deep well injected, remain on the land for evaporation, or discharged to a surface water body.  If a surface water body is it fishing bearing or not and what is downstream of tbe discharge point

    - what are the regualted parameters that the treated effluent  must meet I your region

    - how much land space is available to you 

    - do you have a mixture of regular city wastewater or do you have industrial wastewater as well?  For example, where I live we had to design the entire system around the fact that we had a beef and a pork rendering plant which resulted in ridiculously high BOD levels (3 to 5 times that of regular city wastewater)

    - if there is any fish rendering plants or vegetable process like a pea processor that goes into the city’s wastewater system be INCREDIBLY careful as the BOD for a fish plant we have found (and I am not exaggerating at all) was In the 10,000 ppm!!!!!!!!!

    - is there chlorine injection and then removal in the final treated wastewater 

    - does the town want a “green solution”

    - what are the levels of the basic parameters such as N, P, K, ammonia, and unionized ammonia (very very important for fish)

    - are you required to do a downstream impact study

    - will the treated wastewater pass the T50 trout mortality test

    Tbe list actually is longer than just this but it gives you an idea of how complex wastewater treatment is. Like the others have said, contact a number of vendors and give them the parameters they ask for and start there.  And remember....we are always here to help you!!!!

    Sincerely,

    Kurt Rasmussen, P.Eng. 

    1 Comment

    1. I added a file with the characterization of the wastewater os 3 different points of the drainage network, evendough 2 and 3 are on highly obstructed areas, so maybe not tat representative.The discharge limits by law. The treated wastewater will be discharged on a river, and is close to reach the ocean. The land is abou 6000 m2. Thank you for your feedback!

  24. I would advise you to discuss with a local engineering company with a good expertise in wastewater treatment to take a right decision. There is no a unique answer but it shall consider several aspects, some of which were already discussed by colleagues. May be you should reconsider your question and change it or give more information.

  25. Hi Lara, 

    The critical determinant - is the expertise of the engineer who should take the sewage water quality samples (preferably on seasonal basis), analyze the results against the constraints of the particular project including discharge/reuse requirements, land availability etc.. There could be a number of different methods/treatment techniques to achieve the outcome required. No need to restrain to one only. I would rather write a functional specification - here is the sewage quality coming in - and here is the water quality that we want - going out. Then go to the market and ask those good treatment companies out there to provide you with a solution.  Otherwise - you are relying on the expertise of one company/engineer against the combined expertise of the market. 

    Best of luck with your project!

     

    Regards,

     

    Iouri

  26. The composition of the wastewater is not the deciding factor. The choice of treatment process depends upon the volume to be treated, available space, costs of construction and quality of the discharge required.

    Trickling filters or RBCs are generally the first choice for small municipal works; they are cheaper to operate and maintain than activated sludge but occupy a larger area relative to the flow treated. Activated sludge is typically used for populations larger than about 50,000 but this is highly variable - it depends on the price/availability of land. Activated sludge is also better if there is a requirement to remove nitrogen from the wastewater, since trickling filters can't provide the anoxic conditions needed to remove nitrates. Activated sludge is also preferred in cold regions because trickling filters are susceptible to freezing.

    If there is insufficient land for activated sludge, or if the discharge quality requirements are so tight that it makes economic sense, processes like membrane bioreactors are used, but at the expense of higher capital and operating costs.

    Industrial effluent is more highly variable and the treatment process can depend on the characteristics, for example trickling filters can be used to cool hot effluent.

    1 Comment

    1. Pleased to see a mention of volume and may also need the diurnal variation taken into consideration. In amongst all the high tech responses and if the flow and load are small then consideration may be given to a reed plant based system. Thought I'd balance the debate with a low tech response.

      1 Comment reply

      1. Thanks, and point taken. I'm a big fan of low tech processes too, where space permits. I had interpreted the question as being more narrow - a choice between TF and AS - but it could equally be interpreted as an open choice of processes which should include reed beds, lagoons, constructed wetlands, etc.

  27. Hi Lara; the critical determinant includes: output regulatory standard to be achieved, reuse standard if any, operator capability to operate but technically and financially. There are many options for solutions. We are getting quite clean water from a low O&M cost and easy to operate technology that use layers of gravel and plants to clean. Please see test results attached for a poor tribal village with low levels of affordability and skills to operate. Water being used for irrigation.

     

     

  28. Selection of specific technology depends on (a) requirement for treatment efficiency of technology wrt BOD, COD, TSS, NO3, PO4 ETC., to meet the discharge norms for treated sewage.(b) Land and power availability   (c) Life time cost of technology including capital and O&M expenses

    GOPAL