The commonly used COD parameter does not differentiate between inert and biodegradable organic matter in wastewaters. This differentiation is quite necessary and significant for industrial effluents with high organic content. In such strong wastes the soluble influent COD fraction may severely interfere with the treatability results or challenge the effluent limitation criteria adopted for different industrial categories. The methods suggested in the literature to identify this fraction are not designed to differentiate between soluble inert organic matter and soluble residual microbial products generated during the experiments. This paper proposes two different methods for the assessment of the initial soluble inert COD fraction and summarizes their comparative evaluation. The methods are tested for five different industrial wastes characterizing pulp and paper, meat processing, antibiotics, textile and dairy effluents with total soluble COD concentrations ranging from 1000 to 9300 mgl−1. The results indicate significant interference of soluble residual microbial products which may be identified and corrected for with the proposed methods.

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Some agro-industries generate wastewaters with very high COD concentrations and require two-stage biological treatment Inert or residual organic constituents of these wastewaters, even at very low ratios, play a major role in the compliance of effluent standards. In this study, two strong wastes, citric acid plant effluent and cheese whey were tested for their inert COD content. The experiments showed that the first-phase anaerobic treatment provided a major decrease in the residual COD, but introduced significant amounts of particulate residual COD to the second phase. A newly developed procedure was used for the assessment of the soluble and particulate residual COD.

Laboratory experiments were carried out to evaluate the feasibility of the biological removal of nitrogen from mixed textile (80%) and municipal (20%) wastewater. Three modified “Ludzack Ettinger” bench scale plants were used. Wastewater characterization and process kinetic constants were evaluated experimentally. The results of this experience demonstrated that long sludge age is necessary in order to overcome the nitrification inhibitory effect of some compound(s) that were present in the treated wastewater. Moreover it can be concluded that experimental approaches are necessary to make reliable design of a full scale industrial wastewater treatment plant.

In this study, a large number of textile plants in Turkey have been studied and evaluated in terms of characteristics and treatability of wastewaters involved as related to relevant production parameters, exhibiting significant differences for each plant. Certain industrial groups have been identified to possess different pollution profiles and treatability specifications within the same subcategory. The results observed lead to conclude that the suhcategorization now in use for the textile industry needs to be reformulated by taking care of the significant components defining the nature of this industry, and it has to show more connection with treatability evaluations.