Bioaugmentation With Sewage Microflora To Enhance Performance Of Bioslurry Reactor In Degrading Contaminated Soil

摘要

Bioaugmentation was studied in bioslurry reactor for the degradation of pendimethalin contaminated soil using domestic sewage microflora by adopting sequencing batch mode (anoxic-aerobic-anoxic) operation under aerobic condition. The present study reports on the application of bioaugmentation technique by sewage microflora to bioslurry phase reactor for treating pendimethalin contaminated soil by sequencing batch mode operation. Process performance is assessed by monitoring pendimethalin concentration and biochemical process parameters viz., pH, oxidation reduction potential (ORP), dissolved oxygen (DO) and oxygen consumption rate (OCR) during sequence (batch) operation. quantitative determination of pendimethalin in the bioslurry reactor was carried out by high performance liquid chromatography (HPLC). Total sequence/cycle period of 120 h of cycle period comprising 3 hours of filling phase, 114hours of reaction phase and 3 hours of decant phase at pendimethalin concentration of 500μg/g was studied in three reactors. Control reactor without any microflora showed about 17 % of substrate removal, which may be attributed to the volatile nature of the substrate. Reactor operated with native soil miroflora showed much lesser (3%) degradation over control reactor indicating the toxic nature of the substrate over the slurry biosystem. Bioaugmented reactor showed enhanced process performance wherein about 90 % of the substrate was found to be removed within 72 hours of cycle operation. The improved performance of the reactor may be attributed to the augmentation of the reactor native microflora with domestic sewage, which is considered to be economical and ecofriendly option over other bioagumentation strategies. The survival and retention of added inoculum is important aspect for any bioaugmentation system to be successful. The added inoculum in the system either to participate in the ongoing biodegradation process or transfer the requisite properties to the native microflora. In the present system, the soil microflora was not sufficient enough to mineralize the substrate present in the soil matrix and further augmented inoculum in the form of domestic sewage increased the availability of microorganism which (by increasing food to microorganism ratio) resulted in degradation of the substrate rapidly leading to successful bioaugmentation.