ANAEROBIC TREATMENT OF CHEESE-PRODUCTION WASTE-WATER USING A UASB REACTOR

Dairy wastewater comes mainly from the washing of the installations, and due to its medium content of organic matter it is well suited for a biological treatment, especially an anaerobic treatment. A laboratory scale (4 litres) UASB reactor was operated for more than a year, fed with wastewater from a cheese production industry. An organic loading rate (Bv) of 31 g COD/litre per day (tBAR = 1.7 h) and a COD reduction near to 90% were reached, operating in steady-state conditions using a wastewater with a COD influent of 2050 mg/litre (BOD 1300 mg/litre). The effluent COD was 215 mg/litre (BOD 80 mg/litre). Organic loading rate peaks higher than 45 g COD/litre per day were sporadically reached with COD reductions of 70-80%. The reactor operated with great stability once it had developed a mature microbial population. Prior to this it was necessary to add some alkali in order to maintain the buffer capacity of the system. Biomass granulation occurred during the operation of the reactor after a sudden increase in organic loading rate. This allowed a more stable operation of the reactor.