INFLUENCE OF PLASTICS ON THE ANAEROBIC-DIGESTION OF HIGH CELLULOSIC CONTENT WASTE MATERIALS

Amongst the different low level radioactive wastes (LLW) the high cellulosic stream is the most common. This waste stream consists of paper, wood and a variety of plastics. The presence of these plastics alter the degree of anaerobic digestibility. A kinetic study on the anaerobic digestion of synthetic LLW containing various types of plastics (Polythene, Latex, Neoprene and PVC) was carried out batchwise over a period of 128 days. The results showed biogas production from the anaerobic process to follow a first order kinetic reaction. Experimental data pairs, namely the biogas volume yielded (G) and time (t), fitted the equation: G = G(m)[1-exp(-K0t)]. The theoretical ultimate biogas production (G(m)) and the specific rate constant, K0, were determined from experimental data. The rates of reaction, as described by the constant K0, were shown to be influenced by the presence of both the plastic and rubber components; reasons for this are postulated. No significant differences were found in total gas production and as such is consistent with the basic kinetic theory proposed.