Investigations on aerobic thermophilic treatment of pulp mill effluent

Abstract

Thermophilic treatment of wastewaters increases in importance as industries shift from end-of-pipe treatment towards integrated process water treatment. The need for treatment of process water becomes evident, as the levels of pollutants in industrial water circuits need to be controlled whereas the intake of fresh water generally diminishes. In the paper and pulp industry, high process water temperatures prevail and thus wastewater treatment needs to take place under thermophilic conditions. This thesis describes research in which the aerobic treatment of paper and pulp mill effluent was investigated under thermophilic conditions. The objectives of this study were, firstly, to identify a suitable inoculum for thermophilic degradation of pulp mill effluent and this was achieved by screening from various sources i.e., activated sludge, heating water, soil and compost. The second objective was to determine the feasibility of aerobic thermophilic degradation of pulp mill effluent using temperatures of 40°C, 50°C and 60°C. Batch, fed-batch and continuous experiments would enable the feasibility of degradation of pulp mill effluent. Prior to fed-batch systems, batch systems were optimised by determining the following parameters: 1) Effect of temperature on degradation of pulp mill effluent, 2) Effect of biomass concentration on degradation of pulp mill effluent, 3) Effect of aeration on degradation of pulp mill effluent, and 4) the effect of nutrient supplementation. I I I I I I I I I I I I I I I I I I I I I Once batch systems were optimised, the fed-batch systems came into play, and this system demonstrated much potential for thermophilic degradation of pulp mill effluent, which finally led to developing a continuous system, were degradation was optimal.