SBR operates as a batch process. Because sequential batch reactors operate as a batch process, level of basin starts out low and basin fills over several hours as influent enters.

For complete removal of Nitrogen through ASP, solid retention time considered is 3-18 days. However, this depends on temperature. In case temperature is very low, n solid retention time considered would be around 15-18 days. For higher temperatures, lower solid retention time is considered.

BOD load in Kg/day = Inlet BOD in mg/l x Flow in m³/day /1000 =1000 x 300 / 1000=300 Kg/day. Theoretical oxygen requirement = BOD load x Kg of O₂/Kg of BOD= 300 x 1.8 = 540 Kg of O₂/day.
Standard O₂ Requirement = Theoretical O₂ requirement/ Alpha x [Beta x Csw – D.O.] x Theta^(Tww-20°C)/ C_ss= 540/24/[0.7 x [0.95 x 8.64 ? 2] x 1.024^(30-20)]/9.86=48 Kg of O₂/hr. Air requirement = Actual Oxygen requirement/ (Density of air x % of O₂ in air by weight x SOTE%) = 48/( 1.201 x 0.232 x 0.1599)= 875 m³/hr. Factors assumed: SOTE=17.27%; Alpha=0.7; Beta=0.95; Theta=1.024; Surface saturation C=7.97 (Calculated); Site basin saturation C_sw=8.64 (Calculated); Standard basin saturation C_ss=9.86 (Calculated).
Number of fine diffusers required = 875/6=146. (flow rate considered for fine diffusers is 6 m³/hr).

A sewage treatment plant providing both primary and secondary treatment is expected to remove at least 85 percent of BOD and suspended solids from domestic sewage.

H₂S is highly soluble in water. Hydrogen sulphide poisoning is one of leading causes of accidents. If its concentration is above 5 ppm moderate odour is present. If its concentration increases above 300 ppm, it leads to unconsciousness and death.

The organisms in reactor multiply by feeding of organic solids present in reactor. The reactor consists of wastewater containing organic solids.

Centrifuge is used for dewatering sludge. This is also used for thickening sludge. The or methods for dewatering sludge are done by a filter press, lagoons, sludge drying bed, belt filter press and Reed bed.

After treatment, BOD demand decreases. BOD stands for biological oxygen demand and COD stands for chemical oxygen demand.

When filling/ aeration phase is complete, aeration system shuts off and basin begins to function as a secondary clarifier. Suspended solids and micro-organisms settle to bottom of tank and clarified water is left near surface.

Various standard conditions are mentioned for aeration process. The standard temperature is considered to be 20?C along with 1 atmospheric pressure, zero salinity and zero dissolved oxygen.