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Abstract. The toxicity of pure phenol, formaldehyde, and industrial wastewater, containing phenol and formaldehyde, from a resin production plant was evaluated using aquatic organisms from different taxonomic groups. Test organisms included mixed bacterial culture, unicellular green algae Scenedesmus quadricauda (Turp.) Breb., crustacea Daphnia pulex de Geer (daphnids), and fish Oncorhynchus mykiss Call, 1990 (rainbow trout).Formaldehyde was found to be more toxic to the mixed bacterial culture (120h ECso = 34.1 mg L-L), algae (24h ECso = 14.7 mg L-I), and crustacea (48h ECso = 5.8 mg L -1) than phenol. Phenol proved to be more toxic to fish (48h LCso = 13.1 mg L -~) than to the mixed bacterial culture (120h EC.so = 510 mg L-I), algae (24h ECso = 403 mg L-I), and crustacea (48h ECso = 25 mg L-l). The toxicity of the industrial wastewater to the mixed bacterial culture, algae, and crustacea was caused mainly by formaldehyde, but for fish the presence of phenol in the wastewater proved to be the significant reason for toxicity. Differences in sensitivity of the selected test organisms were also observed, with fish and crustacea being the most sensitive species.

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BACKGROUND: Landfill leachate is a heavily polluted liquid with important environmental impact. It can be generated in a landfill for a long time. During each phase of a landfill life cycle, landfill leachate with specific composition is produced and its treatment has to be optimized accordingly. Phytoremediation offers many benefits compared with conventional treatment methods. However, leachate can have a negative impact on plants and thus it is essential to evaluate the potential risk of landfill leachate for plants employed in phytoremediation. RESULTS: Phytotoxicity and composition of two landfill leachates were studied. Phytotoxicity testing and physico‐chemical parameters showed that the leachate generated in the active part of the landfill was significantly polluted and more toxic to plants than the leachate generated in the closed part of the landfill, which did not cause any significant adverse effects on root growth of plants tested in soil. However, the highest toxic effect of both leachates has been observed in the first days of plant germination. CONCLUSION: Phytotoxic pollutants have probably been degraded in the closed part of the landfill and leachates from such landfills are not significantly toxic to plants. Therefore phytoremediation appeared to be an appropriate restoration and treatment method. Copyright © 2012 Society of Chemical Industry

Kinetics and efficiency of Fenton’s and ozonation processes for the pretreatment of two landfill leachates (fresh and mature) resulting from municipal waste disposal were studied. Both samples presented high organic load, high toxicity and low biodegradability. These were the reasons why oxidative treatment was proposed. Fresh and mature leachate showed different behaviors in the oxidation experiments. The final extents of removal were attained in comparable time intervals in both oxidation systems. Maximal removal of organics by the Fenton’s oxidation reached more than 50 % according to COD. Zero or first order kinetics were found the best to describe the organic components (in terms of COD and DOC) removal by the Fenton’s oxidation for both landfill leachates. Higher reaction rate values of the Fenton’s oxidation were achieved with fresh leachate samples. The efficiency of initial organics removal with ozone was about 70 % for mature leachate, while in case of the fresh one only 41 % of COD were removed. The best fits of COD and DOC experimental data from oxidation of fresh and mature leachates were obtained by a combined kinetic model. No significant improvement of the biodegradability of landfill leachates was achieved using these treatment procedures. Regarding toxicity, ozonation showed to be more effective than the Fenton’s oxidation. Advanced oxidation experiments confirmed that the Fenton’s oxidation and ozonation are comparable oxidative treatment techniques for the reduction of organic pollution in the investigated municipal landfill leachates. However, neither of them is effective enough to be used as a pretreatment method followed by biological treatment.

This study compares efficiency of Fenton's oxidation and ozonation of 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) as two possible processes for removal of estrogens from aqueous solutions. The effectiveness of Fenton's oxidative removal was studied at different ratios of reagents Fe2+:H2O2 (1:0.5; 1:10; 1:20; 1:33), where with some molar ratios up to 100% removal of E2 and EE2 was achieved in the first few minutes of reaction. The best molar ratio for E2 (17beta-estradiol) removal was 1:33, while in the case of EE2 the most efficient one was 1:20 ratio. Ozonation was much faster, because complete removal of estrogens was achieved in 30 seconds (pH approximately eaqual 6), but the time of ozonation was extended up to 60 minutes trying to decompose formed by-products, expressing estrogenic activity, detected by YES (Yeast Estrogen Screening) assay. The obtained results showed that the removal efficiency of estrogens from waters should be assessed by a combination of chemical analyses and bioassay.

The aim of our research was to evaluate the acute and chronic toxicity of wastewater from the pharmaceutical industry to some aquatic organisms. The toxicity of three 24h proportional samples of wastewater was determined with the acute toxicity tests using the bacterium Vibrio fischeri and daphnid Daphnia magna. The inhibition of bacterial luminescence was measured after a 30 min exposure period and the immobility of daphnids was determined after 24 and 48h. The chronic effects on daphnid survival and reproduction were observed for three weeks. The toxicity tests indicated that all investigated samples were acutely toxic to the organisms, but in each sample the responses of bacteria and daphnids were quite different. Acute and chronic effects on daphnids were observed when testing the first sample of wastewater, but no influence on bacteria was determined. The second sample was acutely toxic to both organisms. The third sample was toxic only to bacteria, while no influence on daphnid survival and reproduction was found. The reason for the different toxicity of the samples lay in their compositions. The comparison between chemical analyses and toxicity data showed that for daphnids the main cause of toxic effects was zinc.