9th International Conference on Environmental Science and Technology, Rhodes Isl, Greece, 1 - 03 September 2005
In this study the wastewaters originating from solid waste transport stations that are established to compress the collected solid wastes from households in order to ease further transportation to final disposal sites (e.g. sanitary landfills) are investigated in terms of characterization and treatability. The solid waste transport station receives the solid wastes of approximately 1.5 million population and a flowrate of approximately 70 m3/day is generated as a result of the compression process and the site cleaning operations. The results of conventional characterization showed that although the strength of wastewater may subject to changes depending on the amount of water used for site cleaning, the effluents can be classified as a strong nature one. Unlike the landfill leachates the mentioned wastewaters did not contain excessive amounts of nitrogen. As a wastewater with a high organic content is obtained and since soluble COD of the wastewaters accounted for approximately 80% of the total COD, biological processes (eg. anaerobic processes, aerobic activated sludge technologies or combinations of them such as anaerobic followed by an aerobic one) can be prescribed for the treatment of the mentioned effluents. Current understanding of biodegradability of the wastewaters mainly focuses on the assessment of the inert COD content of the treated effluents. The inert (recalcitrant) COD of the biologically treated effluents on the other hand is composed of two different fractions: the initially inert COD originated from the untreated wastewater, that by-passes the treatment system without being involved in biochemical processes; and the metabolic inert products that are generated thoughout the course of the biological treatment of biodegradable organic matter. There is experimental evidence in literature that the level of inert COD fractions, either initially present or generated as metabolic products varies a great deal with the type (anaerobic or aerobic) of the biological processes applied. Thus the wastewater under investigation is subjected to inert COD fractionation experiments to identify the proper type of treatment. Assessment of inert COD fractions under aerobic and anaerobic conditions indicated that slightly better results can be obtained when anaerobic treatment is applied. However as it is not possible to meet the discharge standarts of 160 mg/l COD with only anaerobic treatment, a treatment scheme composed of an anaerobic process followed by an aerobic one must be the preferred treatment alternative to comply the discharge limitations.