Anaerobic Digestion of Nssc Pulping Effluent

Abstract

<p>Two UASB reactors R-I and R-II, each of 10liters capacity, made up of acryl material were<br />operated parallel and continuously for a period of 220 days, using actual effluent of the NSSC pulp and paper<br />mill, at mesophilic temperature and neutral pH. The main objective was to investigate the treatability<br />performance of the reactors at varying OLR and HRT in terms of TOC and lignin removal. The reactor R-I was<br />used by conventional procedure, whereas, for the reactor R-II methanol and activated carbon was added to<br />supplement its efficiency. Corresponding to an optimum OLR of 4.5kg/m3-day and HRT of 18hrs, the reactor<br />R-II gives 69% TOC and 60% lignin removal. But, in the reactor R-I at same operating conditions, only 56%<br />TOC and 51% lignin removal was noticed. However, the biogas yield in the reactor R-I was noticed relatively<br />more than in the R-II. The biogas yield observed was 0.28m3/kg-CODrem and 0.18m3/kg-CODrem in the reactor<br />R-I and R-II, respectively, with 56-58% methane content in both the reactors. The average VFAs concentration<br />observed in the reactor R-I and R-II is 360mg/L and 230mg/L, respectively. The results of this study suggest<br />that the use of methanol and activated carbon to enhance the treatability efficiency of the UASB reactor is a<br />viable option for the treatment of NSSC pulping effluent.</p>