Treatment of farm dairy effluent with hybrid upflow multilayer bioreactor and activated sludge module

摘要

Biological removal of nitrogen and carbon from farm dairy effluent (FDE) was studied with twonlaboratory-scale systems following nitrification and denitrification processes. Each systemnconsisted of an upflow multilayer bioreactor (UMBR) as a pre-denitrification unit, an aeration tankn(AT) as nitrification unit and a secondary clarifier. The optimization of two operational variables,ntotal hydraulic retention time (HRT) and internal recycle (IR) rate with both real-FDE and ansynthetic-wastewater were investigated. First, HRTs of 2, 3, 4 and 5 days were tested withnsynthetic-wastewater at uniform IR rate. The HRT of 4 days proved optimum with high efficienciesnfor nitrification (.90%), denitrification (.90%) and total chemical oxygen demand (COD) removaln(,90%). The lowest efficiency was recorded at 2 days HRT with 7% nitrification efficiency. Thisnwas followed by experimentation with IR rates of 200%, 300% and 400% on both real-FDE andnsynthetic-wastewater at optimized HRT. The increase in IR to 300% improved the denitrificationnpotential and overall performance with continuous high nitrification efficiency and COD removalnwhereas IR of 400% retarded the process. The application of combined UMBR and activatednsludge system showed good potential for biological removal of nitrogen from FDE.