CHẤT LƯỢNG NƯỚC THẢI CỦA CÁC NHÀ MÁY ĐƯỜNG, NHÀ MÁY CỒN VÀ VIỆC SỬ DỤNG TRONG CANH TÁC NÔNG NGHIỆP

The study was carried out in some of sugar and ethanol plants in Thanh Hoa province with four wastewater treatment systems: wastewater from sugar plant with well chemical and biological treated; wastewater from sugar plant with chemical treatment and semi - biological treatment; wastewater from sugar plant without chemical treatment goes through reservoirs and to drainage systems; and wastewater from ethanol plant. Research results showed that wastewater from first system meets irrigation standard, wastewater the second and third systems needs to be treated for color, odor, suspended solids, NH4 + , E. coli, coliform, BOD5, COD. Molasses from alcohol plant is very rich of nitrogen, phosphorus, potassium, calcium, magnesium but violated some others items of color, odor, total sediment, suspended solids, DO, BOD5, COD, chloride, sulfide, and total lubricant. Wastewater from sugar plant partially met for water demand and plant nutrition for dry land nearby the factory ưhile molasses from alcohol plant can replace a lot of nutrients in fertilizer. However, its impact on soil quality and environment should be observed and asessed before making recommendation to the farmer.