Performance evaluation of septic tanks as onsite sanitation system

Onsite sanitation with septic tanks is popular in most of the Asian countries. The case study conducted in Hanoi and suburban area of Bangkok indicates that the septic tanks employed did not perform as required. The septic tanks just convert the suspended pollutants into dissolved form and release them to the environment due to insufficient maintenance. Thus the effluent from the septic tank is very high in COD, BOD, TKN, NH4+-N, PO4-3 and suspended solids concentrations. Training on the operation and maintenance of septic tanks is essential if they are to be promoted as onsite sanitation systems. Community level septic tanks should be encouraged in order to facilitate post septic tank hybrid treatment systems to be installed in the future upgrades.