Treatment of high-strength industrial wastewater with the temperature-phased anaerobic sequencing batch reactor (ASBR) system has shown positive results in laboratory scale studies. The system achieved COD removals as high as 95% and 90% for soluble and total COD, respectively, up to COD loadings of 22 g COD/L/day. Non-fat dry milk was used as a synthetic substrate.

The system consisted of two reactors operated in series at different temperatures. Phase I of the system was operated at 55°C and the Phase II was operated at 35°C. The total hydraulic retention time in the system was 18 hours (6 hours in the Phase I and 12 hours in the Phase II). The temperature-phased system incorporates advantages of both thermophilic treatment (high reaction rates) and mesophilic treatment (higher quality effluent) while minimizing the disadvantages such as odors commonly associated with thermophilic treatment and lower treatment rates of mesophilic treatment.

This study was conducted using ASBRs. The ASBR was developed at Iowa State University by R.R. Dague. This process allows biomass to increase in the reactors and provides an environment for granulation to occur. Although the ASBR was used for these studies, the temperature-phased process is applicable to other anaerobic treatment processes as well.

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