INTRODUCTION: The kinetics of the transformation of ammonia and acid gases into components of PM2.5 has been examined. The interactions of existing aerosols and meteorology with the transformation mechanism have also been investigated. The specific objective was to discern the kinetics for the gas-to-particle conversion processes where the reactions of NH3 with H2SO4, HNO3, and HCl take place to form (NH4)2SO4, NH4NO3, and NH4Cl, respectively, in PM2.5. MATERIALS AND METHODS: A Teflon-based outdoor environmental chamber facility (volume of 12.5 m3) with state-of-the-art instrumentation to monitor the concentration–time profiles of precursor gases, ozone, and aerosol and meteorological parameters was built to simulate photochemical reactions. RESULTS AND DISCUSSION: The reaction rate constants of NH3 with H2SO4, HNO3, and HCl (i.e., k S, k N, and k Cl) were estimated as (1) k S = 2.68 × 10−4 (±1.38 × 10−4) m3/μmol/s, (2) k N = 1.59 × 10−4 (±8.97 × 10−5) m3/μmol/s, and (3) k Cl = 5.16 × 10−5 (±3.50 × 10−5) m3/μmol/s. The rate constants k S and k N showed significant day–night variations, whereas k Cl did not show any significant variation. The D/N (i.e., daytime/nighttime values) ratio was 1.3 for k S and 0.33 for k N. The significant role of temperature, solar radiation, and O3 concentration in the formation of (NH4)2SO4 was recognized from the correlation analysis of k S with these factors. The negative correlations of temperature with k N and k Cl indicate that the reactions for the formation of NH4NO3 and NH4Cl seem to be reversible under higher temperature due to their semivolatile nature. It was observed that the rate constants (k S, k N, and k Cl) showed a positive correlation with the initial PM2.5 levels in the chamber, suggesting that the existing surface of the aerosol could play a significant role in the formation of (NH4)2SO4, NH4NO3, and NH4Cl. CONCLUSIONS: Therefore, this study recommends an intelligent control of primary aerosols and precursor gases (NO x , SO2, and NH3) for achieving reduction in PM2.5 levels.

PURPOSE: Ciprofloxacin (CIP), a broad-spectrum, second-generation fluoroquinolone, has frequently been found in hospital wastewaters and effluents of sewage treatment plants. CIP is scarcely biodegradable, has toxic effects on microorganisms and is photosensitive. The aim of this study was to assess the genotoxic potential of CIP in human HepG2 liver cells during photolysis. METHODS: Photolysis of CIP was performed in aqueous solution by irradiation with an Hg lamp, and transformation products were monitored by HPLC-MS/MS and by the determination of dissolved organic carbon (DOC). The cytotoxicity and genotoxicity of CIP and of the irradiated samples were determined after 24 h of exposure using the WST-1 assay and the in vitro micronucleus (MN) test in HepG2 cells. RESULTS: The concentration of CIP decreased during photolysis, whereas the content of DOC remained unchanged. CIP and its transformation products were not cytotoxic towards HepG2 cells. A concentration-dependent increase of MN frequencies was observed for the parent compound CIP (lowest observed effect level, 1.2 μmol L−1). Furthermore, CIP and the irradiated samples were found to be genotoxic with a significant increase relative to the parent compound after 32 min (P < 0.05). A significant reduction of genotoxicity was found after 2 h of irradiation (P < 0.05). CONCLUSIONS: Photolytic decomposition of aqueous CIP leads to genotoxic transformation products. This proves that irradiated samples of CIP are able to exert heritable genotoxic effects on human liver cells in vitro. Therefore, photolysis as a technique for wastewater treatment needs to be evaluated in detail in further studies, not only for CIP but in general.

PURPOSE: When fossil fuels on the Earth are used up, which kind of green energy can be used to replace them? Do every bioenergy generation or crop food chain results in environmental pollution? These questions are major concerns in a world facing restricted supplies of energy and food as well as environmental pollutions. To alleviate these issues, option biogases are explored in this paper. MATERIALS AND METHODS: Two types of biogas generators were used for modifying the traditional crop food chain [viz. from atmospheric CO2 photosynthesis to crops, crop stem/husk biowastes (burnt in cropland or as home fuels), to livestock droppings (dumping away), pork and people foods, then to CO2], via turning the biowaste pollutants into green bioenergies. By analyzing the traditional food chain via observation method, the drawbacks of by-product biowastes were revealed. Also, the whole cycle chain was further analyzed to assess its “greenness,” using experimental data and other information, such as the material balance (e.g., the absorbed CO2, investment versus generated food, energy, and wastes). RESULTS AND DISCUSSION: The data show that by using the two types of biogas generators, clean renewable bioenergy, crop food, and livestock meat could be continuously produced without creating any waste to the world. The modification chain largely reduced CO2 greenhouse gas and had a low-cost investment. The raw materials for the gas generators were only the wastes of crop stems and livestock droppings. Thus, the recommended CO2 bioenergy cycle chain via the modification also greatly solved the environmental biowaste pollutions in the world. CONCLUSIONS: The described two type biogases effectively addressed the issues on energy, food, and environmental pollution. The green renewable bioenergy from the food cycle chain may be one of suitable alternatives to fossil and tree fuels for agricultural countries.

The present study aims to investigate the EDTA catalyzed reduction of nitrate (NO 3 − ) by zero-valent bimetallic (Fe–Ag) nanoparticles (ZVBMNPs) in aqueous medium and to enumerate the effect of temperature, solution pH, ZVBMNPs dose and EDTA concentration on NO 3 − reduction. Batch experimental data were generated using a four-factor Box–Behnken design. Optimization modeling was performed using the response surface method for maximizing the reduction of NO 3 − by ZVBMNPs. Significance of the independent variables and their interactions were tested by the analysis of variance and t test statistics. The model predicted maximum reduction capacity (340.15 mg g−1 NO 3 − ) under the optimum conditions of temperature, 60 °C; pH 4; dose, 1.0 g l−1; and EDTA concentration, 2.0 mmol l−1 was very close to the experimental value (338.62 mg g−1) and about 16 % higher than the experimentally determined capacity (291.32 mg g−1). Study demonstrated that ZVBMNPs had higher reduction efficiency than Fe0 nanoparticles for NO 3 − . EDTA significantly enhanced the NO 3 − reduction by ZVBMNPs. The EDTA catalyzed reduction of NO 3 − by ZVBMNPs can be employed for the effective decontamination of water.

PURPOSE: Urbanization and industrialization in China has resulted in a dramatic increase in the volume of wastewater and sewage sludge produced from wastewater treatment plants. Problems associated with sewage sludge have attracted increasing attention from the public and urban planners. How to manage sludge in an economically and environmentally acceptable manner is one of the critical issues that modern societies are facing. METHODS: Sludge treatment systems consist of thickening, dewatering, and several different alternative main treatments (anaerobic digestion, aerobic digestion, drying, composting, and incineration). Agricultural application, landfill, and incineration are the principal disposal methods for sewage sludge in China. However, sewage sludge disposal in the future should focus on resource recovery, reducing environmental impacts and saving economic costs. RESULTS: The reuse of biosolids in all scenarios can be environmentally beneficial and cost-effective. Anaerobic digestion followed by land application is the preferable options due to low economic and energy costs and material reuse. CONCLUSION: It is necessary to formulate a standard suitable for the utilization of sewage sludge in China.

PURPOSE: The purpose of the research is to investigate the applicability of the low-cost natural biosorbents for the removal of Pb(II) ions from aqueous solution and effluent from battery industry. METHODS: Six different biosorbents namely rice straw, rice bran, rice husk, coconut shell, neem leaves, and hyacinth roots have been used for the removal of Pb(II) ions from aqueous solution in batch process. All the biosorbents were collected from local area near Kolkata, West Bengal, India. The removal efficiency was determined in batch experiments for each biosorbent. RESULTS: The biosorbents were characterized by SEM, FTIR, surface area, and point of zero charge. The sorption kinetic data was best described by pseudo-second-order model for all the biosorbents except rice husk which followed intraparticle diffusion model. Pb(II) ions adsorption process for rice straw, rice bran, and hyacinth roots were governed predominately by film diffusion, but in the case of rice husk, it was intraparticle diffusion. Film diffusion and intraparticle diffusion were equally responsible for the biosorption process onto coconut shell and neem leaves. The values of mass transfer coefficient indicated that the velocity of the adsorbate transport from the bulk to the solid phase was quite fast for all cases. Maximum monolayer sorption capacities onto the six natural sorbents studied were estimated from the Langmuir sorption model and compared with other natural sorbents used by other researchers. The Elovich model, the calculated values of effective diffusivity, and the sorption energy calculated by using the Dubinin–Radushkevich isotherm were indicated that the sorption process was chemical in nature. The thermodynamic studies indicated that the adsorption processes were endothermic. FTIR studies were carried out to understand the type of functional groups responsible for Pb(II) ions binding process. Regeneration of biosorbents were carried out by desorption studies using HNO3. Battery industry effluents were used for the application study to investigate applicability of the biosorbents. CONCLUSION: The biosorbents can be utilized as low-cost sorbents for the removal of Pb(II) ions from wastewater.

INTRODUCTION: The toxic effect of the oxidation hair dyes on Phanerochaete chrysosporium was investigated by exposure of this fungus in a nitrogen-limited culture medium to various concentrations of the oxidation hair dyes. RESULTS: The results showed that both the size and the dry weight of the mycelial pellets of P. chrysosporium could be reduced when the concentration of the oxidation hair dyes was higher than 300 mg/L. By using the AFLP analysis and the UPGMA dendrogram, the DNA damage of P. chrysosporium by the oxidation hair dyes was also detected. Comparing with that in the control, the percent polymorphism under different concentrations of the oxidation hair dyes increased. In the meantime, the DNA similarity was decreased, which meant that the DNA damage was aggravated with an increase in the concentrations of the oxidation hair dyes. CONCLUSION: Thus, as an environmental pollutant, the oxidation hair dyes have a toxic effect on P. chrysosporium at both cellular and molecular levels.

This study investigated the effects of pH (6–10) and ozone dose [0.4–3.0 mg O3/mg dissolved organic carbon (DOC)] on the content and structure of haloacetic acid (HAA) precursors in groundwater rich in natural organic matter (NOM; DOC 9.85 ± 0.18 mg/L) during drinking water treatment. The raw water was ozonated in a 2 L glass column. NOM fractionation was carried out using XAD resins. HAA formation potential (HAAFP) was determined according to standard EPA Method 552. NOM characterization revealed it is mostly hydrophobic (65 % fulvic and 14 % humic acids). Hydrophobic NOM significantly influences HAA formation, as confirmed by the high HAAFP (309 ± 15 μg/L). Ozonation at pH 6–10 led to changes in NOM structure, i.e. complete humic acid oxidation, and increased the hydrophilic NOM fraction content (65–90 % achieved using 3.0 mg O3/mg DOC). The highest degree of NOM oxidation and HAA precursor removal was achieved at pH 10 (up to 68 % HAAFP). Ozonation pH influenced the distribution of HAA precursor content, as increasing the pH from 6 to 10 increased the reactivity of the hydrophilic fraction, with the HAAFP increasing from 19.1 ± 6.0 μg/mg DOC in raw water to 152 ± 8 μg/mg DOC in ozonated water. The degree of HAA precursor removal depends on the dominant oxidation mechanism, which is related to the applied ozone dose and the pH of the oxidation process. Ozonation at pH 10 favours the mechanism of radical NOM oxidation and was the most effective for HAAFP reduction, with the efficacy of the process improving with increasing ozone dose.

INTRODUCTION: Lakes play an important role in socioeconomic development and ecological balance in China, but their water quality has deteriorated considerably in recent decades. In this study, we investigated the spatial–temporal variations of eutrophication parameters (secchi depth, total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll-a, trophic level index, and trophic state index) and their relationships with lake morphology, watershed land use, and socioeconomic factors in the Yunnan Plateau lakes. DISCUSSION: Results indicated that about 77.8% of lakes were eutrophic according to trophic state index. The plateau lakes showed spatial variations in water quality and could be classified into high-nutrient and low-nutrient groups. However, because watersheds were dominated by vegetation, all eutrophication parameters except chlorophyll-a showed no significant differences between the wet and dry seasons. Lake depth, water residence time, volume, and percentage of built-up land were significantly related to several eutrophication parameters. Agricultural land use and social–economic factors had no significant correlation with all eutrophication parameters. Stepwise regression analyses demonstrated that lake depth and water residence time accounted for 73.8% to 87.6% of the spatial variation of single water quality variables, respectively. Redundancy analyses indicated that lake morphology, watershed land use, and socioeconomic factors together explained 74.3% of the spatial variation in overall water quality. The results imply that water quality degradation in the plateau lakes may be mainly due to the domestic and industrial wastewaters. This study will improve our understanding of the determinants of lake water quality and help to design efficient strategies for controlling eutrophication in the plateau region.