Application of Ultrasonic Wave Irradiation for Hydrolysis and Amortization of Ability of Biological Analysis of Organic Substances in Dairy Wastewater; Case Study: Tehran Pegah Dairy Complex

In dairy industries large amount of water is utilized and major parts disposed as wastewater. The concentration of organic substance in this wastewater is relatively high. For example in Tehran Pegah Dairy Complex (TPDC) as the biggest Iranian a dairy producer, around 3500 cube meter of wastewater generated for processing of 1000 tons milk, per day. The concentration of chemical oxygen demand (COD) and 5-days biological wastewater demand (BOD5) is about 3000, 1000 mg/L respectively. In this paper the effects of applying ultrasonic wave irradiation on hydrolysis of chemical oxygen demand in TPDC with 20 kHz operational frequency was investigated. The Samples were taken during one working day from 8 a.m. to 4 p.m. Samples were taken every two hour using composite sampling with constant volume from the outlet of equalization tank. Analysis ofexperimental data showed that it is possible to transfer some part of insoluble COD and BOD5 to soluble form by applying ultrasonic wave. The maximum of this conversion was about 52% which observed at 480s contact time and output power 300 W. For 300 and 600 W output power with extending contact time in the range of 60 to 480s, hydrolysis of organic matter showed ascending trend, but at 900w output powers find out different behavior. Therefore, when hydrolysis of organic matter consider, it is recommended to use low output power and long contact time. And it is important to considering that by this conversion, achievement the high level of treatment become more feasible and a reduction in the cost of treatment obtained consequently.