Anaerobic Process for Treating Sewage

The Anaerobic process for treating sewage is considered to be an economical and eco-friendly process. The process involves digestion of organic material in the sewage in the absense of air and produces biogas.

Sewage treatment through anaerobic processes works effectively in removing biodegradable organic compounds and has advantages of reduction in the amount of the sludge being produced. The biogas produced during the process also acts a source of energy , making the overall process energy efficient. Microbiology of the anaerobic process for treating sewage The proces of degradation occurs in 4 stages :

  • Hydrolysis: complex undissolved materia broken into less complex compunds through enzymes secreated by acidogenic bacteria. The products of this process are used as substrates for the bacteria
  • Acidogenesis :products formed during the hydrolysis step get diffused into bacterial cells of fermentative bacteria where dissolved compounds in the sewage get converted into simple materilal producing fatty acids , alcohols , lactic acids and new cell materia.
  • Acetogenesis :Acetogenic bacteria act on products from the acideogenesis stage and convert them into acetate , carbon dioxdie , hydrogen and new cell material.
  • Methanogenesis :The final stage of anaerobic degradation of the organic matter occurs in this stage where methane gets produced from acetic acid.


Few Conditions to be met for anaerobic reactor systems are as follows :

  • Sufficient contact time between the microbes in the sewage (biomass) and the wastewater.
  • The biomass needs to be adapted and acclimitized well to be able to handle the specific characteristics of the wastewater .
  • High retention rate of the viable biomass in the reactor to be able to increase the loading of the system.

High rate anaerobic secondary treatment of wastewater was designed to handle high strength industrial wastewater characterised with very high COD . Munipal sewage treatment in most parts of the world deal with concentration of sewage below 1000 mg/l.

In the initial developmental stages of biological wastewater treatment through anaerobic processes there were limitations such as uncontrolled green house gas emission that occured due to financial constraints. With multiple there were multiple issues assciated with the anaerobic process for sewage treatment , it has big potentional to solve major wastewater related problems in developing countries.

Robust microbial formulation for sewage treatment with Cleanmaxx STP cleanmaxx-stp

The main advantages and constraints of the anaerobic process of treating sewage are as follows:

-At least 90% cost saving in operational costs due to lesser energy requirements.

-40-60% cost saving in investment costs due to lesser requirement of treatment units.

-Methane produced can be used as a source for energy.

-Can handle high hydraulic loads and organic loads

-Excess sludge production is low and sludge can be easily stabilized and dewatered for efficient disposal .


    • Collected methane produced is often not recovered
    • Gases like H2S produced might escape causing odour problems.
  • The produced methane gets dissolved in the effluent and measures are not taken to prevent the CH4 from espacing into the atmosphere.
Post by Karen Sam