Treatability of hazardous substances in industrial wastewater: case studies for textile manufacturing and leather production sectors.

Hazardous substances used and produced by different industrial activities pose a potential risk to the environment and to human health. Different physicochemical and/or biological processes are used in industrial wastewater treatment; these methods, however, may not be effective in removing these substances. This study was carried out to comparatively evaluate the removal of hazardous substances through conventional wastewater treatment processes that are used by major industries in Turkey. A four-season monitoring study was carried out in textile manufacturing and leather production sectors, representing industrial activities in Turkey. Samples were analyzed for 45 priority substances defined by the European Union and 250 specific pollutants listed in the Turkish Regulation on Surface Water Quality. For both wastewaters, where biological treatment was performed after pretreatment, their characteristics showed that organics were almost completely removed. except for dichloromethane (44-51% removals) and dioxin and dioxin-like compounds (64-69% removals). Additionally, different removal ratios (16-97%) were obtained for metals; the poorer removal was observed for B, Ba, Ag, Sb, and Si. The remaining metals (Cu, Pb, Sb, V, Si for textile; Cr, Cu, Sb, Si for leather effluents) in the treated wastewaters were still higher than environmental quality standards (EQS) of receiving water bodies. The study revealed that existing treatment processes were not adequate for efficient hazardous substance removal and there is an urgent need to improve them. Finally, advanced treatment technologies were suggested for specific pollutants together with their unit treatment costs.

An approach for determining the nutrient sensitive areas: a case study for Gediz River Basin, Turkey.

This study presents an approach to the determination of nutrient sensitive areas (SA) based on National Urban Wastewater Treatment Regulation harmonized under the Water Framework Directive (WFD). A three-stage approach that covers designation of potential sensitive areas (PSA) which are under the risk of eutrophication, physicochemical and biological monitoring at PSA, and application of the suitable biotic indices is used for the determination of sensitive areas. PSA are identified as a result of either available monitoring data or if this is not available according to indexing method which developed in this study based on pressure and impact analysis. The Gediz River Basin, one of the most polluted basins in Turkiye, is chosen as a pilot area. According to the results of the study, 40% of the total drainage area of the basin was designated as sensitive area.

Utility of a source-related matrix in basin management studies: a practice on a sub-Basin in Turkey.

According to the water framework directive (WFD), the chemical status should be determined for each water body in a basin through monitoring and evaluation studies, and the gap between the status of water bodies and good water status should be revealed in river basin management plans. In this context, the methodology starting with the evaluation of the monitoring results of the priority substances (PSs) until the end of determining the measures to achieve good condition in surface waters was given in this study. The key aim was to provide a useful methodology defined as a matrix for determining the sources of pollutants that caused this gap. This matrix was applied to the most polluted sub-basin of Küçük Menderes Basin located on the western part of the Turkey. Monitoring studies were carried out in 21 water bodies for a 1-year period for 45 PSs and monitoring results were compared with environmental quality standards (EQS). It was determined that 13 of 45 PSs in 15 water bodies exceeded the EQS. The common PSs in the basin were lead, nickel, fluoranthene, benzo(a)pyrene, C10-13 chloroalkanes, and 4-nonylphenols and average rates of exceeding the EQS were 58.3%, 36.4%, 91.5%, 99.9%, 74.8%, and 49.4%, respectively. The detailed emission inventory of each water body in the basin has been made. Potential sources of PSs were searched via the matrix formed and a total number of 420 basic and supplementary measures were proposed to improve the water quality of the sub-basin.

A strategy for the implementation of water-quality-based discharge limits for the regulation of hazardous substances.

Many developing countries apply technology-based discharge standards that set quantitative limits on pollutant discharges. These standards do not inherently consider ambient constraints and, therefore, cannot guarantee to protect aquatic life from hazardous pollutants. It is a challenge for developing countries to enforce water-quality-based limits for wastewater discharges and guarantee the intended use of water. This study aims to develop a strategy that suits the needs of developing countries for a transition from technology-based discharge standards to water-quality-based discharge limits. To this end, a pilot monitoring program was carried in the Gediz River Basin in Turkey. Surface water, industrial, and urban wastewater samples were collected and analyzed for 45 priority pollutants identified by the European Union and 250 national river basin specific pollutants. The monitoring results revealed that the environmental quality standards (EQSs) were exceeded for 8 priority, and 28 specific pollutants. This finding indicated that the existing technology-based discharge standards are not satisfactory to guarantee the intended water quality, and there is a need for adopting a new strategy for the implementation of water-quality-based discharge limits in Turkey. As a widely applied approach for determining water-quality-based discharge limits, firstly, conservative mass balance with and without consideration of mixing zone was evaluated. The results indicated that this approach was not applicable due to the receiving environment concentrations being higher than the EQSs. As an alternative approach, the dilution methodology, which considers the level of dilution occurring at the immediate discharge point, was tested. The results proved that the dilution methodology is the most appropriate strategy for developing countries with relatively poor surface water quality to improve the water quality to the level where the conservative mass balance approach can be applicable.

Potential risk assessment of metals in edible fish species for human consumption from the Eastern Aegean Sea.

The levels of Hg, Cd, Pb, Cr, Cu and Zn were measured in the tissues of four edible fish species namely: Diplodus annularis, Pagellus erythrinus, Merluccius merluccius and Mullus barbatus, collected from the Turkish Coast of the Aegean Sea. Except for D. annularis, the levels of Cd and Pb in all fish tissues sampled in Aliaga Bay in 2009 were above the tolerable limits according to the Food and Agriculture Organization of the United Nations (FAO). Hg in P. erythrinus and M. barbatus were higher than the maximum permitted limits (FAO), while D. annularis and M. merluccius were lower than the limit for biota in the district of Aliaga. Although the Target Hazard Quotient (THQ) values for Cd, Pb, Cu, Cr, Zn in all fish samples were lower than 1.0, the THQ for Hg levels were higher than 1.0 for most of the samples. According to the THQ values, M. merluccius may be consumed in moderation from Aliaga Bay, while the consumption of M. barbatus and P. erythrinus collected from Aliaga Bay are potentially hazardous to human health due to the Hg concentrations. Fish collected from Izmir Bay can be consumed safely.

Assessment of improvement scenario for water quality in Mogan Lake by using the AQUATOX Model.

In this study, the improvement scenarios for water quality in Mogan Lake were investigated using the AQUATOX Model. The ecosystem model AQUATOX simulates conventional pollutants, such as nutrients and sediments, and considers several trophic levels, including attached and planktonic algae, submerged aquatic vegetation, several types of invertebrates, and several types of fish. In this study, all data measured at both lakes and creeks was loaded into the AQUATOX Model including both initial concentration and dynamic loading for the year 2002. Then, the AQUATOX Model was calibrated and verified for the years 2004 and 2005. Accordingly, the Aquatox Model was utilized for the analysis of future scenarios as to improve water quality in terms of conventional parameters such as dissolved oxygen, temperature, total suspended solids, pH, total nitrogen, total phosphorus, and labile and refractory organic matters in water colon and sediment. During the development of future scenarios, some plans regarding measures were taken into account the modeling periods. In one of the scenarios, constructed wetlands located in big creeks' mouths were used for improving the water quality in Mogan Lake. The results indicated that Mogan Lake would improve its hypertrophic situation towards eutrophic situation. It would be anticipated that if the situation goes on like this, Mogan Lake would improve eutrophic situation towards mezotrophic situation.