This paper presents results of a comparative evaluation of the feasibility of anaerobic pre-treatment for the effluents from a hardboard and laminated board industry.

The problems associated with the treatment of hardboard mill wastewaters using activated sludge process have been observed as relatively low COD removal, high energy cost and high amounts of excess biological sludge production. The purpose of the study is to evaluate the effectiveness and feasibility of the anaerobic pre-treatment to reduce the excess biological sludge production and energy consumption in the aerobic stage. Anaerobic treatability studies were carried out by a lab-scale upflow anaerobic sludge blanket reactor (UASBR) with an effective volume of 10 litres. The UASBR was operated for a wide range of organic and hydraulic loadings during the experimental studies of more than 4 months. Anaerobic treatability studies have shown that a COD removal of 60% is possible at organic loading rates of 5-11 kg COD/m3.d. Anaerobic treatability study results have shown that 70 percent reduction both in the excess sludge production and in energy for aeration are possible by applying anaerobic pre-treatment. Considering these findings, it was demonstrated that anaerobic pre-treatment is a feasible option for waste management of the hardboard mill effluents.