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.
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!!!!
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!
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.
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.
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.
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.
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.
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.
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