In-Pipe Technology Company, Inc.

Microbiology: The Key to Wastewater treatment case study


The biological treatment of wastewater relies mainly on a consortium of heterotrophic and autotrophic bacteria. The fecal bacteria that are constantly introduced into the collection system are not the optimal bacteria for degrading the contaminants present in wastewaters. The soil bacteria that are introduced through inflow and infiltration are more effective at degrading the wastes and can contribute to stabilizing the downstream wastewater treatment process; however, the flux of these organisms into the sewer system Ls not enough to contribute to significant degradation in the sewer system under normal conditions. Collection system bioaugmentation aims to introduce high concentrations of specific soil bacteria into the outer reaches of the sewer system and amplify the beneficial effects of soil bacteria in the collection system. The downstream impact of this treatment serves to improve the condition of the collection system by reducing cxlor and degrading fats, oils, grease (KXi). as well as reducing organic loadings to waste water treatment plants (WWTPs) and increasing the efficiency and effectiveness of the wastewater treatment process.

Direct releases of domestic, municipal, or industrial wastewater into surface waters degrade the condition of the natural aquatic environment and can pose serious threats to human health. Biological treatment processes are still the mainstay for degrading most of wastewater contaminants after pre-treatment (e.g., screening and settling) since it is the most effective process in contaminant degradation, cast effective, and it is eco-friendly compared to the physicx'hemicai processes. Advanced chemical and/or biological treatments, such as chemical precipitation or tertiary filtration are often required before reuse or discharge into ecologically sensitive waters. In a biological process, indigenous micr
Wastewater Bacteria And Their Metabolisms
Fecal heterotrophic and natural autotrophic bacteria are the indigenous micrrganisms introduced into the biological wastewater treatment processes. Heterotrophic bacteria degrade readily biodegradable COD (rbCOD) in wastewater by using it as an electron donor for respiration. They respire using oxygen, nitrate, or sulfate, as an electron acceptor under aerobic, anoxic, or anaerobic conditions, respectively. The main  respiration products are carlx>n dioxide, nitrogen gas, sulfide, and bio-mass. Heterotrophic bacteria also degrade rbC.OD through the fermentation processes under anaerobic conditions and generate the fermentation products of carix>n dioxide and biomass. Autotrophic nitrifiers oxidize ammonia to nitrate or nitrite for energy and use alkalinity as a carbon source. Anaerobic respiration using sulfate is undesirable in a wastewater treatment process since  the  respiration product sulfide creates nuisance odors and is also toxic to human health. Furthermore, the sulfide oxidation in the sewer atmosphere generates sulfuric acid, which is corrosive to the sewer infrastructure. In addition, heterotrophic bacteria secrete enzymes to hydrolyze hydrolysafole particulate COD to rfoCOIX which then can foe used as an electron donor for cellular me(alx)lism.

Current Microbiology And Wastewater Treatment
Approximately 99.9% of fecal bacteria are strict anaerolx\s and the rest are either acrolx.\s or facultative anaerobes. Fecal bacteria are more susceptible to the changes in wastewater characteristics and environmental conditions such as temperature, pH, chemistry, etc. Heterotrophic and autotrophic bacteria are the main contributors in wastewater treatment.

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