of Starch Industry Wastewater

A combined biologic and chemical treatment of high-strength (total chemi- cal oxygen demand (CODtoJ up to 20 g/L), strong nitrogenous (totalNup to 1 g/L), and phosphoric (total P up to 0.4 g/L) starch industry wastewater was investigated at laboratory-scale level. As a principal step for COD elimi- nation, upflow anaerobic sludge bed reactor performance was investigated at 30°C. Under hydraulic retention times (HRTs) of about 1 d, when the organic loading rates were higher than 15 g of COD / (L.d), the CODtot removal varied between 77 and 93%, giving effluents with a COD/N ratio of 4-5:1, approaching the requirements of subsequent denitrification. The activated sludge reactor operating in aerobic-anoxic regime (HRT of about 4 d, dura- tion of aerobic and anoxic phases of 30 min each) was able to remove up to 90% of total nitrogen and up to 64% of COD tot from the anaerobic effluents under 17-20°C. The coagulation experiments with Fe (III) showed that 1.4mg of resting hardly biodegradable COD and 0.5 mg of phosphate (as P) could be removed from the aerobic effluents by each milligram of iron added. Index Entries: Activated sludge reactor; coagulation; nutrient removal; starch wastewater; upflow anaerobic sludge bed reactor.