Question

this is an environmental microbiology question.

i’m studying the wastewater treatment. I’m really confused and my question is : can sewage treatment and waste water treatment be considered the same thing? Also, when describing anaerobic and aerobic treatment do they happen both during the sewage treatement process or if one happend there’s no need for the other one?

also, the primary sludge is it further purified by the secondary treatment or is it removed?

Answer 1

waste water treatment is a vast field consisting of all the waste waters like industrial, tanning, dying, household; whereas, sewage waste water is only considered to be the household waste flowing through the sewage channels.

aerobic and anaerobic treatment are two different ways of treating the waste water and either one of them is sufficient enough it does not need the second in many cases but certain requirements of the wastewater like high phosphorus and nitrogen in the waste water must be treated aerobically as well as anaerobically because nitrification requires aerobic conditions and denitrification requires anaerobic conditions so both are treated in a series of tank maintaining aerobic and anaerobic environment. One such process is Bardenpho process which requires both aerobic as well as anaerobic tanks for treating Nitrogen and Phosphorus.

The primary sludge which is generated is further used in activated sludge process where reverse activated sludge plays very important role in reducing the log phase of the microorganisms as the sludge contains microorganisms they are present in the sludge then when sludge is removed from the treated water, it is again reversed back and mixed with the primary influent in the aeration tank this mixture is also known as the MLSS (Mixed liquor suspended solids). Once after reversing it for a number of times the sludge ages and is treated as shown below and removed from the system.