Frakcje ChZT ścieków w mechaniczno-biologicznej oczyszczalni

W pracy przeprowadzono ocenę skuteczności rozkładu zanieczyszczeń organicznych w ściekach po poszczególnych procesach mechaniczno-biologicznego oczyszczania ze szczególnym uwzględnieniem zmian frakcji ChZT w ciągu technologicznym oczyszczalni w Zielonej Górze.

In Polish literature there is little information regarding the distribution of COD fractions, therefore, identify the theoretical topic has been mainly based on foreign literature. Literature data 'tips a COD divided into factions as the most suitable for accurate characterization of organic matter in municipal wastewater. In Poland, continues for many years, to identify the organic matter in wastewater contractual indicators such as BOD5, CODCr, CODMn, organic carbon content and loss during roasting were used. Information on the composition of the effluent, obtained based on these conventional indicators, are much less accurate when compared with data obtained on the basis of COD fractions. In the majority of cases the values of concentration of biodegradable organic matter in wastewater is expressed in BOD5, whereas identification of COD fractions, additionally allows the evaluation of the amount of impurities which are non biodegradable and which decrease the efficiency of biological treatment. The paper presents results of studies concerning the designation of COD fraction in the raw wastewater and their alternations after subsequent processes in mechanical-biological wastewater treatment. The test object was a wastewater treatment plant for the city of Zielona Góra. Sampling of raw wastewater and wastewater after various stages of mechanical-biological treatment, and laboratory tests such as designating pollution indicators such as: CODMn, CODCr, BOD5, BODtot and TOC was performed according to Polish standards. During investigation following fractions of COD were also determined: dissolved non bioderadable SI, dissolved easily biodegradable SS, in organic suspension slowly degradable XS and in organic suspension non-biodegradable XI. Methodology for determining the COD fraction was based on the guidelines ATV A 131. Analysis of results of research concerning changes in fractions of COD in the wastewater treatment plant showed that: 1. More than 75% of the total COD in the raw wastewater inflowing to the wastewater treatment plant "Łącza" were biodegradable fractions: bound in suspension XS and dissolved SS, 2. Technological system of the mechanical-biological wastewater treatment plant in Zielona Góra does not change the solute concentration in the effluent of non-biodegradable dissolved fraction SI, 3. Changes in the percentage contribution of fraction XS, XI, and the SS were a consequence of biochemical changes occurring in the biological part of the plant, 4. CODCr indicator values in all analyzed wastewater samples were lower than the total COD, which is the sum of individual fractions of COD, 5. Differences between the effectiveness of work in the wastewater treatment plant in Zielona Góra based on CODCr and total COD were the order of 1%, 6. The values of the percentage contribution of XS, XI, SI, and SS fraction in the total COD of raw wastewater from Zielona Góra are consistent with the values given in the literature.