Septage treatment with VFCW (India)

In this study, the wastewater collected from a septic tank is passed through a partially converted anaerobic filter and a vertical flow constructed wetland (VFCW) before being sent to a soak pit with objective to check the effectiveness of incorporating a VFCW in between a septic tank and soak pit so as to bring down the consequences created due to effluent seepage from soak pits to the ground water. Conventionally, after primary onsite treatment in septic tank, the effluent gets directly passed on to soak pits and the soak pit walls being made of porous materials allows the gradual seepage of final effluent into the ground and thereby pollute the groundwater reserves. Groundwater pollution by the leachate from soak pits has created a major havoc in India as well as in other countries that is particularly dependent on septic systems and onsite treatment systems. So, in actuality it is uncertain that if the final effluent being sent into soak pits after primary treatment meets the Central Pollution Control Board (CPCB) standards. In this case study we were able to obtain final effluent values after VFCW treatment as 55.7 mg/L for COD, 12.1 mg/L for BOD, 10.2 mg/L for NO3^–, 3.7 mg/L for PO4^3-, 7.4 for pH, 8.3 mg/L for TSS, 379.2 mg/L for TS and 51.9 CFU/100mL for Total Coliforms. With this case study, we were able to resolve this impediment by bringing down the values of all the parameters considered while analysis under the limits of discharge standards set by CPCB. The removal efficiency of COD, BOD, NO3^–, PO4^3-, TSS, TC after wetland was found to be 89, 88, 63, 44, 98, 97, and 97 % respectively. The study has proven that with the introduction of another decentralized treatment system in between a septic tank and soak pit, it is safe to dispose off the effluent into soak pits and thereby reduce the chances of groundwater pollution considerably.