Faculty of Applied Sciences

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Investigations on aerobic thermophilic treatment of pulp mill effluent
(2004) Reddy, Prenaven; Singh, Suren; Pillay, Visvanathan Lingamurti; Buckley, Chris
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.
Toxicity and biodegradability assays for hazardous landfill leachate and textile size effluents
(2005) Rakgotho, Thabisile; Odhav, Bharti; Buckley, Chris
The cumulative effects of pollution have led to increased public concern, which is resulting in strict legislation on the discharge of wastes in whatever state they are present, i.e. solid, liquid or gas. Currently, in South Africa, effluents with a high organic load are sent to landfills or marine outfall because the cost of discharge to sewer is prohibitive. In regions where there is a net surplus of rainfall, landfill sites have the potential to pollute the groundwater due to saturated soil conditions. Therefore, many landfill sites should not receive liquid effluents. If liquid wastes are disposed onto landfills, then an alternate sink is required for the treatment of the high volumes of leachate that are generated. These concentrated effluents could then be treated by biological, chemical or physical methods to reduce the pollution load in the natural water resources. In this study, anaerobic digestion has been identified as one of the biological processes that can be applied to treat high-strength or toxic organic liquid effluents, since a survey conducted by Sacks (1997) indicated that many anaerobic digesters in the KwaZulu-Natal region have spare capacity. However before high strength industrial wastes can be treated in existing anaerobic digesters, their impact on the digestion process, i.e. their toxicity and biodegradability under anaerobic conditions, needs to be determined. During this project, several high-strength or toxic industrial effluents were tested to assess their toxicity and biodegradability under anaerobic conditions. These include three synthetic textile size effluents from the textile industry (Textile effluent 1, 2, and 3) and three hazardous landfillieachates (Holfontein, Shongweni and Aloes). In addition, the components of a textile effluent, i.e., starch and wax, were tested to determine which