The need for - and use of non-fossile fuels such as biogas have increased due to global warming, oil depletion and stricter environmental regulations. Organic wastes can be anaerobically digested in order to produce biogas, which can be utilized to generate heat or electricity. So far, little attention has been directed towards anaerobic digestion of organic wastes from the forest industry. Due to high sludge management costs and more rigorous environmental legislation, the demand for new and/or improved disposal methodologies has increased. Substrate treatment methods such as enzyme addition and ultrasound are of interest in order to make anaerobic digestion of organic wastes, e.g. biological sludge, economically feasible. The aim of this study is to evaluate if biological sludge from the pulp and paper industry can be used for methane production in anaerobic digestion and to investigate the effects of ultrasound pre-treatment and enzyme treatment. The aim of the study was accomplished by performing four batch experiments, during 67-110 days, and a six months laboratory-scale semi-continuous digestion experiment. Substrates were provided by a chemical and a mechanical paper mill, whereas Kemzymes® from Kemira and ultrasound equipment from Ultra Sonus were used for sludge treatment. The short term average accumulation of methane per added g VS rate increased both when ultrasound pre-treatment and enzyme treatment was applied in batch experiments. The enzyme treatment was considered to have a greater potential in larger scale and was consequently used in the semi-continuous digestion experiment. Positive effects of the treatment were however difficult to prove. Adapting the enzyme treatment to be more specific for the degradation of the sludge is recommended. It is possible that there are inhibitory interactions between ultrasound pre-treatment and enzyme treatment. 75% ultrasound pre-treatment is an alternative to complete pre-treatment and renders equivalent average accumulation of methane per added g VS. Storage of ultrasound pre-treated biological sludge at 4°C for six and 13 days does not affect the average accumulation of methane per added g VS. Enzyme treatment of biological sludge enhanced the average accumulation of methane per added g VS from indigenous material in the inoculum. It is likely that anaerobic digestion of biological sludge from the pulp and paper industry can render a stable biogas production. High viscosity and agitation problems were predominant in the semi-continuous digestion experiment and can be difficult to control in larger scale. The results from the semi-continuous digestion experiment are similar with those obtained from the batch experiments. The methane production rates in this study are lower (biological sludge from chemical pulp process) or higher (mechanical ditto) in comparison to those presented data by Puhakka et al. (1992). Different types of biological sludge were used and might explain the prevailing differences.

Thesis submitted in fulfilment of Master's Degree in Technology: Biotechnology, Durban Institute of Technology, 2004. / M

The state of Uttar Pradesh occupies about 9 per cent of the total geographical area of India, supports more than 16 per cent of its 440 million people, but has less than 6 per cent of the Indian forests. It is, in many ways, an underdeveloped part of a developing nation. There is a great potential for contributions of Uttar Pradesh to the economic development of India, by the expansion of the U. P. pulp and paper industry. Per capita consumption of paper and paper-board in India is expected to increase from about 1.3 Kg in 1965 to 6.2 Kg in 2000. If the production in the country increases as anticipated in this thesis, and if more raw materials are not made available, shortages of both long-fibred and short-fibred raw materials will begin to be felt strongly by about 1975 and will progressively increase. To reduce these shortages the Uttar Pradesh Forest Department is establishing plantations of fast-growing tree species. The Mysore hybrid eucalypt is being planted to provide short-fibred pulpwood and plantations of the bamboo (D endrocalamus strict us) will yield long-fibred pulp. Present plans of the U. P. Forestry Department have not paid enough attention to growing long-fibred material. The Department should concentrate mainly on the production of long-fibred material because much short-fibred material is available as sugar cane bagasse in the U. P. It also could be secured when needed if eucalypt and poplar plantings were made by farmers. Eucalypts, pines, poplars and bamboos have been discussed regarding their suitability for production of pulpwood in the forest areas of U. P. Greatest attention has been given here to eucalypts but it is concluded that pines and bamboos are the most desirable. The need for producing within India all of the pulp and paper required domestically has been considered more important than that for supplying paper and paper-board to Indian consumers at world prices. At present It appears as if the foreign exchange conserved by reducing pulp and paper imports can be more usefully spent in buying machinery, fertilizers, and technical knowledge. India can become self-sufficient in its paper and paper-board needs after 1980 only if enough long-fibred raw materials are produced. Therefore, major trials of potentially suitable, fast-growing, long-fibred species should be established soon. The paper industry in U. P. should continually strive to improve its technology and bring down its costs of production because in the long run it will have to become competitive in world markets. The U. P. Forest Department should not judge its efficiency solely by the size of net surplus created in a plantation program. It should also consider the potential contributions of its plantations in the growth of Indian industry and improvement of real national income. Intensive economic analyses of the problems discussed here should be undertaken to refine objectives for the long-term development of U. P.'s forest industry. / Forestry, Faculty of / Graduate

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Master of Science