Sewage and sewage sludge from municipal wastewater treatment plant were analyzed for 16 EPA-PAH. The measurements were conducted to investigate the effect of different treatment stages on PAH content in wastewater and sewage sludge. PAH loads in influent, mechanically and biologically treated sewage, as well as in raw, digested and dewatered sludge were calculated. Mechanical and biological treatment was found to remove 85% of PAH from the influent. Despite of this a daily PAH load introduced into environment was high, and reached 37% of the PAH load in the influent. In sewage it was equal to 46 g PAH-lid, with carcinogenic PAH content of 12%. In waste sludge (filter pressed sludge and sand from sand trap) PAH total load reached 68 gid with 17% of carcinogenic PAH.

The paper presents the results of studies on the changes in the PAHs concentration during pre-filtration and ultrafiltration (UF) processes. In the study, biologically treated wastewater (after denitrification and nitrification processes), discharged from the biological treatment plant and used in coke plant, was used. A gas chromatography-mass spectrometry (GC-MS) was used in order to qualify and quantify the PAHs. Sixteen PAHs listed by EPA were determined. The wastewater samples were collected three fold and initially characterized for the concentration of nitrate nitrogen, ammonium nitrogen, COD, TOC and pH. In the first step, wastewater was filtrated on the sand bed. Total concentration of 16 PAHs in the treated wastewater before initial filtration was in the range of 44.8‒53.5 mg/L. During the process the decrease in the concentration of the most studied hydrocarbons was observed. Concentration of PAHs after initial filtration ranged from 21.9 to 38.3 μg/L. After the initial filtration process the wastewater flew to the ultrafiltration module and then was separated on the membrane (type ZW-10). The total concentration of 16 PAHs in the process of ultrafiltration was in the range of 8.9‒19.3 mg/L. The efficiency of removal of PAHs from coke wastewater in the process of ultrafiltration equaled 66.6%. Taking into account the initial filtration, the total degree of removal of PAHs reached 85%. The obtained results indicate the possibility of using the ultrafiltration process with the initial filtration as additional process in the coke wastewater treatment.

The work presents examination results of the common determination of PAHs and PCBs in industrial sludge and supernatants. Sewage sludge was taken from the wastewater treatment plant, and supernatants were obtained by their centrifuging. The prepared samples of sewage sludge and supernatants were subjected to extraction with applying the mixture of organic solvents. Cyclohexane and dichloromethane were used for constant samples, and methanol, cyclohexane and dichloromethane - for liquid. Extracts, after separation from samples of sewage sludge and supernatants, were cleared on the silica gel in vacuum conditions and concentrated in the stream of nitrogen. In such prepared extracts there was conducted the qualitative-quantitative analysis of 16 PAHs using the GC-MS system. Next, the samples were evaporated and poured with water and methanol until the clear solution was obtained. Extracts were cleared on octadecyl C18 columns, and then concentrated in the nitrogen stream. In these extracts PCBs was also determined with the application of the gas chromatograph with mass spectrometer. The range of concentrations 16 PAHs in sewage sludge equalled 10-16 mg/kgd.w. Summary average concentration 16 PAHs in supernatants was reached 17 μg/L. Average recovery of PAHs introduced to sewage sludge in the form of reference mixture was 78% (with consideration of naphthalene). In the case of supernatants, the average value of recovery reached 60%. Average PCBs concentration in supernatants equalled 10 ng/L. For sewage sludge the sum of marked PCBs was an average 1.23 μg/kgd.w.. In the case of particular PCBs the percentage recovery of the reference mixture for supernatants was 86%, while for sewage sludge it was 55%.

The removal of nitrates from aqueous solutions is cumbersome because of their high solubility in water. The use of zero-valent iron (ZVI) for the reduction of nitrates is the chemical process and it is an alternative method to the biological ones. The aim of the present study was to evaluate the eff ectiveness of nitrates removal from water solution by using the ZVI process. The process was coupled with the removal of COD, phosphates and turbidity by using by-products of nitrates reduction. Batch tests were performed to evaluate the eff ectiveness of ZVI in the removal of nitrates from aqueous solutions. The eff ectiveness of nitrates removal was analyzed after 5, 10, 20, 30 and 60 min. and compared to the initial concentration of pollutants. Simultaneously analysis of ammonium nitrogen and nitrites was controlled to identify products of nitrates reduction under various pH. The removal of COD, phosphates and turbidity was also performed in batch tests. The eff ectiveness of the emoval by using three types of chemicals was compared – PIX, FeSO4, and waste Fe2+/Fe3+ from the ZVI process. The results obtained in the study indicate that ZVI can be eff ectively used in the treatment of water polluted with nitrates and the by-products of the process could be further applied in the removal of COD, phosphates and turbidity. Based on the results the method should be advised as a promising alternative to the technologies used nowadays under technical scale as a technology that fits with a circular economy.

The aim of the investigation was to determine the impact of the presence of Zn in concentrations of sludges applied in agriculture (exceeding concentrations determined in sludges drained from the treatment plant) 011 the disappearance of PAHs in sewage sludge stored under aerobic conditions. The studies were carried out using dewatered and biochemically stabilized sludges. The changes in the concentration of PAHs were studied in four series: in sludge samples taken after filter press, in sludge with the addition of a standard PAH mixture. in sludge with Zn added, in sludge with the addition of both the standard PAH mixture and Zn. The standard PAH mixture used in the studies contained 16 compounds in benzene - dichloromethane (I: ł) solution with a concentration of 32000 ug/cm' of 16 PAHs. Zn was added to the sludge samples as a solution of chloride zrnc. the final amount was below 2500 mg Zn/kg d.m. (taking into consideration the initial concentrations) The sludge samples were incubated for 90 days at 20°C with limitless access of oxygen. The determination of PAHs in sludge samples was done in duplicates at the beginning of the experiment (the initial concentration) and then six times at I 5-day intervals (after 15. 30. 45. 60. 75 and 90 days). A gas chromatography-mass spectrometry (GC-MS) was used to qualify and quantify the PAHs. I 6 PAI-ls listed by EPA were identified

This paper presents the results of investigation on polycyclic aromatic hydrocarbons (PAHs) concentration in sludge coming from industrial wastewater treatment. The sludge was characterised according to chemical composition and heavy metal contents. Leaching of PAHs from sludge in dynamic conditions was also done with lizymetric columns used to simulate the real conditions during the storage of wastes. The changes or PAHs concentration in sludge stored under various lights conditions were also compared (daylight and darkness). A periodic extraction method with cyclohexane was used to select PAHs from samples. High performance liquid chromatography (HPLC) with fluorescent detector was used to analyse PAHs. Six PAHs listed by WHO were analysed (fluoranthene Fl, benzo(b)fluoranthene BbF, benzo(k)fluoranthene BkF, benzo(a)pyrene BaP, benzo(ghi)perylene BghiP and indeno(l ,2,3-cd)pyrene IP).