We have installed a biogas generating Effluent Treatment Plant for the 60 KLPD Cane Molasses based distillery at Siddapur village. SDL is taking all the precautionary measures as stipulated by the State and Central Pollution Control Boards for achieving Zero Discharge by way of installing Bio-methanisation Plant followed by Bio Composting or On-land irrigation.
TECHNICAL DETAILS
The ETP is designed for the following wastewater characteristics.
Flow – 600 m3/day
pH – 4 – 4.3 S.U.
COD – 1,30,000 mg/L
BOD – 60,000 mg/L
Process Description
Raw effluent i.e. raw spent wash (RSW) from the distillery shall be carried to treatment site through suitably designed channel or a closed pipe depending upon the topography of the site. Raw spent wash shall then be passed through heat exchanger to bring down the temperature to 38 – 40 OC. raw spent wash is mixed with part of reactor effluent for pH adjustment in the buffer tank. Pumps are installed, to pump the mixed effluent from buffer tank to SMAT reactor. The overflow from the SMAT (anaerobic) reactor shall be taken to the existing bio-composting process for attaining zero discharge or shall be discharged on-land as per the norms through controlled application or fertirrigation.
The SMAT Reactor will be rested on floating type foundation. It will be erected and fabricated at site using mild steel plates of designed thickness conforming to I.S. 2062.
The Reactor will be painted from inside using chlorinated rubber paint, whereas the outside surface will be painted by synthetic enamel or aluminum paint as per client preference.
The SMAT Reactor is partially packed with structured media made out of PVC. The entire media remains submerged in the reactor content. The bacteria grow and reside on large surface area provided by media. The bacteria developed on media surface takes upon organic content of wastewater to metabolize it and produce biogas and biomass.
The reactor content is kept under constant re circulation using recirculation pumps. Each recirculation pump is connected to the suction network, placed next to the bottom of the reactor. This suction network is designed in such a way that it sucks reactor content from entire bottom cross sectional area. Thus the possibility of formation of dead zone is eliminated and the entire reactor is kept active.
The treated effluent is collected from the top of the reactor. To utilize head available, the overflow arrangement is so designed that the treated effluent is discharged at suitable head.
The biogas produced by anaerobic digestion inside the reactor is collected at the Gas Dome. The biogas is then conveyed to blower for further utilization in boiler or biogas engines.
Performance Projections in the SMAT reactor
Upon reaching the steady sate the systems would produce the following results, when operated under optimum design conditions:
- BOD Removal 85 % + 5 %
- COD Removal 65 % + 5 %
- PH 7.0 – 7.5
- Biogas Production 0.53 + 5 % m3 /Kg COD removed
Average Gas Composition
- Methane content : 50 % – 60 %
- Hydrogen Sulfide : 2.5 % – 3.5 %
- Carbon Dioxide : 36.5 % – 47.5 %.