Deivid Ismael Kern

Toxicity and genotoxicity of hospital laundry wastewaters treated with photocatalytic ozonation.

The aim of the present study was to assess the efficiency of advanced oxidative processes based on photocatalytic ozonation (O(3), UV, UV/O(3), UV/O(3)/Fe(2+) 50 mg L(-1) and 150 mg L(-1)) in the treatment of hospital laundry wastewaters. The analysis of the investigated wastewater revealed high chemical oxygen demand (COD - 3343.8 mg L(-1)), biochemical oxygen demand (BOD(5) - 1906.4 mg L(-1)), total Kjeldahl nitrogen (TKN - 79.8 mg L(-1)) and Daphnia magna toxicity (EC50=1.73). Genotoxic effects were also detected for Allium cepa. Reductions of some parameters occurred after photocatalytic ozonation. The UV/O(3)/Fe(2+) 150 mg L(-1) method was more efficient in reducing COD (59.1%), BOD(5) (50.3%) and TKN (86.8%). There was significant reduction (p<0.05) in D. magna toxicity, O(3) (EC50=47.3%), UV (EC50=50.6%) and UV/O(3)/Fe(2+) 150 mg L(-1) (EC50=45.4%) processes. Normalization of the mitotic index and reduction of micronucleated cells were observed in A. cepa after the treatments. Results demonstrate that these methods were efficient in the degradation of hospital laundry wastewaters, representing a thriving alternative for the removal of pollutants that cause toxicity and genotoxicity.

Evaluation of the toxic effects of four anti-cancer drugs in plant bioassays and its potency for screening in the context of waste water reuse for irrigation

Anti-cancer drugs are compounds that are of high environmental relevance because of their lack of specific mode of action. They can be extremely harmful to living organisms even at low concentrations. The present study evaluated the toxic effects of four frequently used anti-cancer drugs against plant seedlings, namely Cyclophosphamide (CP), Methotrexate (MTX), 5-Fluorouracil (5-FU) and Imatinib (IM). The phytotoxicity experiments were performed with Lactuca sativa seedlings whereas cytotoxicity, genotoxicity and mutagenicity investigations were performed with the well-established Allium cepa assays. MTX was the most phytotoxic compound, followed by 5-FU, CP and IM. Significant differences in the Mitotic Indexes (MI) were observed in three of the studied compounds (MTX, 5-FU and CP), indicating potential cytotoxic activity of these substances. Chromosome aberrations were registered in cells that were exposed to 5-FU, CP and IM. All the four compounds caused the formation of micronucleated cells indicating mutagenic potential. Besides, the assays performed with MTX samples presented a high number of cell apoptosis (cell death). Although it is unlikely that the pharmaceuticals concentrations measured in the environment could cause lethal effects in plants, the obtained results indicate that these compounds may affect the growth and normal development of these plants. So, both tests can constitute important tools for a fast screening of environmental contamination e.g. in the context of the reuse of treated wastewater and biosolids of agricultural purpose.

Constructed Wetlands Integrated with Advanced Oxidation Processes in Wastewater Treatment for Reuse

The development of integrated systems for wastewater treatment has been investigated in recent years not only for the improvement of control parameters but also to allow the routine reuse of wastewater to be effectively implemented. Several studies also seek to add processes that may reuse by-products, energy, and unit operations in a single integrated remediation unit. Considering the sustainability scenario, all these processes should be designed and controlled with description of scope, mass inventory, and energy demand in order to establish indexes of environmental pressure. Classical publications of books and articles for wastewater treatment have already described to more than 10 years several procedures and standards for reuse (direct or indirect), segregation at source, required treatment levels, groundwater recharge, combination of remediation processes, logistics, and sanitation. In this case, further investigation to decentralized systems, such as reed bed filters, with reduced costs of implementation and operation is required, as well as the simplicity of units to be installed. This tendency of integrated phytoremediation systems supports the growing interest for the combination of a system already considered classic in wastewater treatment, the constructed wetlands (CWs), with advanced oxidation processes (AOPs), particularly the photocatalysis with direct or indirect use of solar energy. Because of its already reported disinfection and detoxification potentials which might enable the reuse of urban wastewaters for some specific purposes, the photocatalytic treatment was selected for a study of case. So, this chapter covers the phenological aspects of a macrophyte still little used in phytoremediation, the Hymenachne grumosa; the evolution of the combined use of Upflow Anaerobic Sludge Blanket systems (UASB) + CWs; and the integration of the processes UASB + CWs + UV /TiO2/O3 with indirect use of solar energy in photoreactors designed for these studies.