Solar photo-oxidation of recalcitrant industrial wastewater: a review

Conventional methods to clean wastewater actually lead to incomplete treatments, calling for advanced technologies to degrade recalcitrant pollutants. Herein we review solar photo-oxidation to degrade the recalcitrant contaminants in industrial wastewater, with focus on photocatalysts, reactor design and the photo-Fenton process. We discuss limitations due to low visible-light absorption, catalyst collection and reusability, and production of toxic by-products. Photodegradation of refractory organics by solar light is controlled by pH, photocatalyst composition and bandgap, pollutant properties and concentration, irradiation type and intensity, catalyst loading, and the water matrix.

     

Advanced physico-chemical treatment experiences on young municipal landfill leachates

In this study, Membrane Filtration (UF+RO), Struvite (MAP) precipitation and ammonia stripping alternatives were studied on biologically pre-treated Landfill Leachate. The results indicated that the system including the Upflow Anaerobic Sludge Blanket Reactor (UASBR) and Membrane Reactors (UF+RO) has been offered as an appropriate treatment alternative for young landfill leachates. This system provided high removals of COD, colour and conductivity (>98-99%). For ammonia removal, struvite precipitation was applied at the stoichiometric ratio (Mg:NH4:PO4=1:1:1) to anaerobically pre-treated raw landfill leachate effluent having an influent ammonium concentration of 2240 mg/l. Maximum ammonium nitrogen removal was observed as 85% at pH of 9.2. In ammonia stripping following 2 h of aeration, the removal was 72% at pH=12 while the removals were around 20% at pH=10 and pH=11. When membrane reactor, and struvite precipitation or ammonia stripping was applied to anaerobically pre-treated effluents, the results indicated that each system could be used as an appropriate post-treatment option for young landfill leachates. In economic aspect, ammonia stripping was found as the cheapest alternative with high ammonium removal. However, when both high COD and ammonium removals were to be achieved membrane technology such as UF+RO (SW) could be considered as the most appropriate system due to the fact that COD removal could be obtained very low by ammonia stripping.     

Assessment of ambient air quality in Eskişehir, Turkey

This paper presents an assessment of air quality of the city Eskişehir, located 230 km southwest to the capital of Turkey. Only five of the major air pollutants, most studied worldwide and available for the region, were considered for the assessment. Available sulphur dioxide (SO₂), particulate matter (PM), nitrogen dioxide (NO₂), ozone (O₃), and non-methane volatile organic carbons (NMVOCs) data from local emission inventory studies provided relative source contributions of the selected pollutants to the region.The contributions of these typical pollution parameters, selected for characterizing such an urban atmosphere, were compared with the data established for other cities in the nation and world countries. Additionally, regional ambient SO₂ and PM concentrations, determined by semi-automatic monitoring at two sites, were gathered from the National Ambient Air Monitoring Network (NAAMN). Regional data for ambient NO₂ (as a precursor of ozone as VOCs) and ozone concentrations, through the application of the passive sampling method, were provided by the still ongoing local air quality monitoring studies conducted at six different sites, as representatives of either the traffic-dense-, or coal/natural gas burning residential-, or industrial/rural-localities of the city. Passively sampled ozone data at a single rural site were also verified with the data from a continuous automatic ozone monitoring system located at that site. Effects of variations in seasonal-activities, newly established railway system, and switching to natural gas usage on the temporal changes of air quality were all considered for the assessment. Based on the comparisons with the national [AQCR (Air Quality Control Regulation). Ministry of Environment (MOE), Ankara. Official Newspaper 19269; 1986.] and a number of international [WHO (World Health Organization). Guidelines for Air Quality. Geneva; 2000. Downloaded in January 2006, website: http://www.who.int/peh/; EU (European Union). Council Directive 1999/30/EC relating to limit values for sulfur dioxide, nitrogen dioxide and lead in ambient air. Of J Eur Communities L 163: 14–30; 29.6.1999; EU (European Union). Council Directive 2002/3/EC relating to ozone in ambient air. Of J Eur Communities. L 67: 14–30; 9.3.2002.; USEPA (U.S. Environmental Protection Agency). National Ambient Air Quality Standards (NAAQS). Downloaded in January 2006, website: http://www.epa.gov/ttn/naaqs/] ambient air standards, among all the pollutants studied, only the annual average SO₂ concentration was found to exceed one specific limit value (EU limit for protection of the ecosystem). A part of the data (VOC/NO_x ratio), for determining the effects of photochemical interactions, indicated that VOC-limited regime was prevailing throughout the city.     

Municipal solid waste management strategies in Turkey

Municipal solid waste (MSW) is a major environmental problem in Turkey, as in many developing countries. Problems associated with municipal solid waste are difficult to address, but efforts towards more efficient collection and transportation and environmentally acceptable waste disposal continue in Turkey. Although strict regulations on the management of solid waste are in place, primitive disposal methods such as open dumping and discharge into surface water have been used in various parts of Turkey. This study presents a brief history of the legislative trends in Turkey for MSW management. The study also presents the MSW responsibility and management structure together with the present situation of generation, composition, recycling, and treatment. The results show that approximately 25 million ton of MSW are generated annually in Turkey. About 77% of the population receives MSW services. In spite of efforts to change open dumping areas into sanitary landfills and to build modern recycling and composting facilities, Turkey still has over 2000 open dumps.     

Stronger predation in the tropics shapes species richness patterns in marine communities

Species interactions are widely assumed to be stronger at lower latitudes, but surprisingly few experimental studies test this hypothesis, and none ties these processes to observed patterns of species richness across latitude. We report here the first experimental field test that predation is both stronger and has a disproportionate effect on species richness in the tropics relative to the temperate zone. We conducted predator-exclusion experiments on communities of sessile marine invertebrates in four regions, which span 32 degrees latitude, in the western Atlantic Ocean and Caribbean Sea. Over a three-month timescale, predation had no effect on species richness in the temperate zone. In the tropics, however, communities were from two to over ten times more species-rich in the absence of predators than when predators were present. While micro-and macro-predators likely compete for the limited prey resource in the tropics, micropredators alone were able to exert as much pressure on the invertebrate communities as the full predator community. This result highlights the extent to which exposure to even a subset of the predator guild can significantly impact species richness in the tropics. Patterns were consistent in analyses that included relative and total species abundances. Higher species richness in the absence of predators in the tropics was also observed when species occurrences were pooled across two larger spatial scales, site and region, demonstrating a consistent scaling relationship. These experimental results show that predation can both limit local species abundances and shape patterns of regional coexistence in the tropics. When preestablished diverse tropical communities were then exposed to predation for different durations, ranging from one to several days, species richness was always reduced. These findings confirmed that impacts of predation in the tropics are strong and consistent, even in more established communities. Our results offer empirical support for the long-held prediction that predation pressure is stronger at lower latitudes. Furthermore, we demonstrate the magnitude to which variation in predation pressure can contribute to the maintenance of tropical species diversity.     

Latitudinal variation in local interactions and regional enrichment shape patterns of marine community diversity

While communities are shaped by both local interactions and enrichment from the regional species pool, we propose a hypothesis that the balance of these forces shifts with latitude, with regional enrichment dominating at high latitudes and local interactions dominating at low latitudes. To test this hypothesis, we conducted a latitudinal-scale experiment with marine epifaunal communities. In four regions of the North Atlantic Ocean and Caribbean Sea, we used mimics of ecosystem engineers to manipulate biogenic structural complexity. We iteratively evaluated diversity patterns of experimental communities up to one year after deployment. Additional data were also collected from one of our tropical sites 2.5 years after initial deployment. As hypothesized, we found a reciprocal latitudinal gradient in the effects of the structurally complex mimics and regional enrichment. In the tropics, local diversity was always higher in association with the mimics than in exposed areas that were more open to predation. This effect was consistent across two spatial scales and beyond the one-year timescale of the experiment. In temperate communities, no consistent effects of the mimics on diversity were observed. However, the proportion of species from the regional species pool that were present at the local scale increased from the tropics to the temperate zone, consistent with the hypothesis that higher-latitude communities may experience greater influence from the regional species pool than communities at low latitudes. This study represents the first large-scale experimental demonstration that suggests that the relative impact of local interactions and regional enrichment on community diversity may depend on latitude.     

Treatment of copper industry waste and production of sintered glass-ceramic.

Copper waste is iron-rich hazardous waste containing heavy metals such as Cu, Zn, Co, Pb. The results of leaching tests show that the concentration of these elements exceeds the Turkish and EPA regulatory limits. Consequently, this waste cannot be disposed of in its present form and therefore requires treatment to stabilize it or make it inert prior to disposal. Vitrification was selected as the technology for the treatment of the toxic waste under investigation. During the vitrification process significant amounts of the toxic organic and inorganic chemical compounds could be destroyed, and at the same time, the metal species are immobilized as they become an integral part of the glass matrix. The copper flotation waste samples used in this research were obtained from the Black Sea Copper Works of Samsun, Turkey. The samples were vitrified after being mixed with other inorganic waste and materials. The copper flotation waste and their glass-ceramic products were characterized by X-ray analysis (XRD), scanning electron microscopy and by the toxicity characteristic leaching procedure test. The products showed very good chemical durability. The glass-ceramics fabricated at 850 degrees C/2 h have a large application potential especially as construction and building materials.     

Assessment of multiple anthropogenic contaminants and their potential genotoxicity in the aquatic environment of Plitvice Lakes National Park,Croatia

In this study, the influence of anthropogenic pollution on the aquatic environment of Plitvice Lakes National Park (PLNP) was investigated during 2011–2012 using a combination of chemical and cytogenetic analyses. Four groups of major contaminants [(volatile organic compounds: benzene, toluene, ethylbenzene, and xylenes (BTEX); persistent organochlorine pollutants: organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs); major and trace elements; anthropogenic radionuclides (⁹⁰Sr, ¹³⁴Cs, and ¹³⁷Cs)] were determined in three aquatic compartments (water, sediment, fish). Mass fractions of inorganic constituents in different compartments reflected the geological background of the area, indicating their origin from predominantly natural sources. Levels of volatile and persistent organic compounds in water and fish, respectively, were very low, at levels typical for remote pristine areas. Analysis of anthropogenic radionuclides in water and sediment revealed elevated activity concentrations of ¹³⁷Cs in water, and measurable ¹³⁴Cs in the upper sediment layers from April 2011, possibly as a consequence of the Fukushima nuclear accident in March 2011. The potential genotoxicity of river and lake water and lake sediment was assessed under laboratory conditions using the alkaline comet assay on human peripheral blood lymphocytes, and measured levels of primary DNA damage were within acceptable boundaries. The results showed that despite the protected status of the park, anthropogenic impact exists in both its terrestrial and aquatic components. Although contaminant levels were low, further monitoring is recommended to make sure that they will not rise and cause potentially hazardous anthropogenic impacts.