Arsenic (As) is a pervasive environmental toxin and carcinogenic metalloid. It ranks at the top of the US priority List of Hazardous Substances and causes worldwide human health problems. Wetlands, including natural and artificial ecosystems (i.e. paddy soils) are highly susceptible to As enrichment; acting not only as repositories for water but a host of other elemental/chemical moieties. While macro-scale processes (physical and geological) supply As to wetlands, it is the [Detail] ...
Fluorescece spectroelectrochemistry is used to probe redox process of benzoquinone.
The benzoquinone reduction state has a lower fluorescence quantum efficiency.
CVF and DCVF can reveal more information about benzoquinone redox reactions.
This method can analyze compounds with fluorescence and electrochemical activities.
Quinones are common organic compounds frequently used as model dissolved organic matters in water, and their redox properties are usually characterized by either electrochemical or spectroscopic methods separately. In this work, electrochemical methodology was combined with two fluorescence spectroelectrochemical techniques, cyclic volta- fluorescence spectrometry (CVF) and derivative cyclic volta- fluorescence spectrometry (DCVF), to determine the electrochemical properties of p-benzoquinone in dimethyl sulfoxide, an aprotic solution. The CVF results show that the electrochemical reduction of p-benzoquinone resulted in the formation of radical anion and dianion, which exhibited a lower fluorescence intensity and red-shift of the emission spectra compared to that of p-benzoquinone. The fluorescence intensity was found to vary along with the electrochemical oxidation and reduction of p-benzoquinone. The CVF and DCVF results were in good consistence. Thus, the combined method offers a powerful tool to investigate the electrochemical process of p-benzoquinone and other natural organic compounds.
he main sources of sand and dust lie in deserts and semi-deserts, such as the Sahara Desert in Africa and the deserts in Central and Western Asia. Dust aerosols directly alter the radiation balance of the earth-atmosphere system by scattering and absorbing short- and long-wave radiation. Dust aerosols indirectly alter the albedo and rainfall patterns by acting as cloud condensation nuclei (CCN) or ice nuclei (IN). Dust aerosols mitigate global warming by altering the amount of CO2 absorbed by the marine phytoplankton.
he main sources of sand and dust lie in deserts and semi-deserts, such as the Sahara Desert in Africa and the deserts in Central and Western Asia.
Dust aerosols directly alter the radiation balance of the earth-atmosphere system by scattering and absorbing short- and long-wave radiation.
Dust aerosols indirectly alter the albedo and rainfall patterns by acting as cloud condensation nuclei (CCN) or ice nuclei (IN).
Dust aerosols mitigate global warming by altering the amount of CO2 absorbed by the marine phytoplankton.
Dust and Sand Storms (DSS) originating in deserts in arid and semi-arid regions are events raising global public concern. An important component of atmospheric aerosols, dust aerosols play a key role in climatic and environmental changes at the regional and the global scale. Deserts and semi-deserts are the main source of dust and sand, but regions that undergo vegetation deterioration and desertification due to climate change and human activities also contribute significantly to DSS. Dust aerosols are mainly composed of dust particles with an average diameter of 2 mm, which can be transported over thousands of kilometers. Dust aerosols influence the radiation budget of the earth-atmosphere system by scattering solar short-wave radiation and absorbing surface long-wave radiation. They can also change albedo and rainfall patterns because they can act as cloud condensation nuclei (CCN) or ice nuclei (IN). Dust deposition is an important source of both marine nutrients and contaminants. Dust aerosols that enter marine ecosystems after long-distance transport influence phytoplankton biomass in the oceans, and thus global climate by altering the amount of CO2 absorbed by phytoplankton. In addition, the carbonates carried by dust aerosols are an important source of carbon for the alkaline carbon pool, which can buffer atmospheric acidity and increase the alkalinity of seawater. DSS have both positive and negative impacts on human society: they can exert adverse impacts on human’s living environment, but can also contribute to the mitigation of global warming and the reduction of atmospheric acidity.
Pollution pattern of metals and organic pesticide in demolition waste is studied.
Organophosphorus pesticide can be everlasting on surface of demolition waste.
Leaching potential of pollutants from simulated and onsite waste varies spatially.
Direct oral and dermal ingestion, leaching potential into water exceed the limit.
Implications for demolition waste management in industrial plants are proposed.
Exploration of heavy metals and organic pollutants, their leaching capacity along with health and environmental risks in contaminated industrial construction and demolition waste (ICDW) within a pesticide manufacturing plant were investigated. A maximum content of 90.8 mg·kg−1 Cd was found present in the wastes, which might originate from phosphorus rocks and industrial sulfuric acid used in pesticide production processes. An average concentration of 979.8 mg·kg−1 dichlorovos and other 11 organophosphorus pesticide were also detected. Relatively high leaching rates of around 4.14‰ were obtained from laboratory simulated ICDW using both glacial acetic acid- sodium hydroxide and deionized water. Pesticide pollutants had the strongest tendency to retaining on dry bricks (leaching rate 1.68‰) compared to mortar-coatings, etc. due to their different physical characteristics and octanol-water partioning coefficient. Mobility of pesticide from on-site ICDW by water was spatially correlated to waste types, process sections and human activities, with a flux of leaching rate between 5.9‰ to 27.4%. Risk-based corrective action (RBCA) model was used to simulate the risk of contaminated ICDW debris randomly scattered. Oral and dermal ingestion amount by local workers was 9.8 × 10−3 and 1.9 × 10−2 mg·(kg·d)−1, respectively. Potential leaching risk to aquatic systems exceeded the limit for nearly 75% waste. Environmental and health risk exceedance was found in most ICDW, while the risk value of the most severely contaminated brick waste was 660 times beyond critical level. Implications for waste management involving construction and deconstruction work, waste transferring and regulation supplying were also provided.
Real wastewater treatment technology diffusion process was investigated.
The research is based on a dataset of 3136 municipal WWTPs and 4634 organizations.
A new metric was proposed to measure the importance of a project in diffusion.
Important projects usually involve central organizations in collaboration.
Organizations become more central by participating in less important projects.
The diffusion of municipal wastewater treatment technology is vital for urban environment in developing countries. China has built more than 3000 municipal wastewater treatment plants in the past three decades, which is a good chance to understand how technologies diffused in reality. We used a data-driven approach to explore the relationship between the diffusion of wastewater treatment technologies and collaborations between organizations. A database of 3136 municipal wastewater treatment plants and 4634 collaborating organizations was built and transformed into networks for analysis. We have found that: 1) the diffusion networks are assortative, and the patterns of diffusion vary across technologies; while the collaboration networks are fragmented, and have an assortativity around zero since the 2000s. 2) Important projects in technology diffusion usually involve central organizations in collaboration networks, but organizations become more central in collaboration by doing circumstantial projects in diffusion. 3) The importance of projects in diffusion can be predicted with a Random Forest model at a good accuracy and precision level. Our findings provide a quantitative understanding of the technology diffusion processes, which could be used for water-relevant policy-making and business decisions.
Indigenous predatory BALO strains were successfully isolated from activated sludge.
Sludge SRF and CST were significantly reduced by BALOs induced biolysis process.
The increase of BALO input dosage promoted the sludge biolysis efficiency.
Sludge biolysis disintegrated flocs and lysed cells for internal water release.
The optimal sludge biolysis time was 24 h and no pH adjustment was needed.
Bdellovibrio-and-like organisms (BALOs) are a group of ubiquitous and obligate predatory bacteria and commonly used as biocontrol agents. In this study, an efficient, environmental-friendly, and convenient BALOs encouraged municipal waste sludge biolysis pretreatment technique was developed and investigated for dewaterability enhancement of excess waste sludge. The indigenous predatory BALOs were successfully isolated from the sludge for biolysis treatment. Without any chemical addition or pH adjustment, the sludge specific resistance (SRF) and capillary suction time (CST) were significantly reduced by as high as 53.4% and 23.8%, respectively within 24 h’s treatment, which would further be lowered with the increase of BALOs input dosage. However, the continuous extension of reaction time would worsen the sludge dewaterability. The decreases of SRF and CST accompanied with the increases of sludge disintegration degree and soluble chemical oxygen demand, nitrogen, and phosphorus concentrations all emphasized the contributions of BALOs’ predation activities to sludge disturbance, cell lysis, and consequently the release of sludge intracellular water to finally effectively improve the sludge dewaterability and disposal efficiency.
Coprecipitation–oxidation method was developed to recover the iron from wastewater.
Fe3O4 nanoparticles were well synthesized from steel waste pickling liquor.
Promoters greatly improved the properties of synthesized Fe3O4 nanoparticle.
Real-time control of the Fe2+/Fe3+ molar ratio was achieved by ORP monitoring.
Waste pickling liquors (WPLs) containing high concentrations of iron and acid are hazardous waste products from the steel pickling processes. A novel combined coprecipitation–oxidation method for iron recovery by Fe3O4 nanoparticle production from the WPLs was developed in this study. An oxidation–reduction potential monitoring method was developed for real-time control of the Fe2+/Fe3+ molar ratio. The key coprecipitation–oxidation parameters were determined using the orthogonal experimental design method. The use of promoters greatly improved the Fe3O4 nanoparticle crystallinity, size, magnetization, and dispersion. X-ray diffraction patterns showed that the produced Fe3O4 nanoparticles were single phase. The Fe3O4 nanoparticles were approximately spherical and slightly agglomerated. Vibrating sample magnetometry showed that the Fe3O4 nanoparticles produced from the WPLs had good magnetic properties, with a saturation magnetization of 80.206 emu·g−1 and a remanence of 10.500 emu·g−1. The results show that this novel coprecipitation–oxidation method has great potential for recycling iron in WPLs.
A combination of adsorption with ozonation proved best for dye removal.
Toxicity of the textile effluents can be remarkably reduced by combined method.
Wide scope for choice of natural materials for treatment of textile dyes.
Intrusion of synthetic textile dyes in the ecosystem has been recognized as a serious issue worldwide. The effluents generated from textiles contain large amount of recalcitrant unfixed dyes which are regarded as emerging contaminants in the field of waste water study. Removal of various toxic dyes often includes diverse and complex set of physico-chemical, biological and advanced oxidation processes adopted for treatment. Adsorption in itself is a well-known technique utilized for treatment of textile effluents using a variety of adsorbents. In addition, ozonation deals with effective removal of dyes using high oxidising power of ozone. The review summarizes dye removal study by a combination of ozonation and adsorption methods. Also, to acquire an effective interpretation of this combined approach of treating wastewater, a thorough study has been made which is deliberated here. Results asserts that, with the combined ability of ozone and a catalyst/adsorbent, there is high possibility of total elimination of dyes from waste water. Several synthetically prepared materials have been used along with few natural materials during the combined treatment. However, considering practical applicability, some areas were identified during the study where work needs to be done for effective implementation of the combined treatment.
The biopolymer showed two protein-like fluorescence peaks (peaks A and B).
Interactions of Pb(II) and biopolymer were quantified at various system pH values.
System pH values significantly affect the quenching constant values for both peaks.
Peak B plays a more important role in the interactions than peak A.
Removal mechanism of metal ions by activated sludge system was further disclosed.
The quantification and effects of system pH value on the interactions between Pb(II) and the biopolymer from activated sludge were investigated. The biopolymer had two protein-like fluorescence peaks (Ex/Em= 280 nm/326–338 nm for peak A; Ex/Em= 220–230 nm/324–338 nm for peak B). The fluorescence intensities of peak B were higher than those of peak A. The fluorophores of both peaks could be largely quenched by Pb(II), and the quencher dose for peak B was about half of that for peak A. The modified Stern-Volmer equation well depicted the fluorescence quenching titration. The quenching constant (Ka) values for both peaks decreased with rising system pH value, and then sharply decreased under alkaline conditions. It could be attributed to that the alkaline conditions caused the reduction of available Pb(II) due to the occurrence of Pb(OH)2 sediments. The Ka values of peak B were bigger than those for peak A at the same system pH values. Accordingly, the aromatic protein (peak B) plays the key role in the interactions between metal ions and the biopolymer.
Microplastic particles smaller than 5 mm in size are of increasing concern, especially in aquatic environments, such as the ocean. Primary source is microbeads (<1 mm) used in cosmetics and cleaning agents and fiber fragments from washing of clothes, and secondary source such as broken down plastic litter and debris. These particles are mostly made from polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyesters. They are ingested by diverse marine fauna, including zooplanktons, mussel, oyster, shrimp, fish etc. and can enter human food chains via several pathways. Strategy for control of microplastics pollution should primarily focus on source reduction and subsequently on the development of cost-effective clean up and remediation technologies. Recent research results on biodegradation of plastics have revealed a potential for microbial biodegradation and bioremediation of plastic pollutants, such as PE, PS and PET under appropriate conditions.
Valerate-hydrolysate enriched culture showed great ability to produce 3HV and 3H2MV.
Valerate-hydrolysate enriched culture had more Brevundimonas in the community.
Mixed iso-/n-valerate was effective at balancing microbial growth and PHAs synthesis.
Co-substrates of valerate and propionate raised the fraction of 3HV and 3H2MV.
The production of polyhydroxyalkanoates (PHAs) with a high fraction of 3-hydroxyvalerate (3HV) and 3-hydroxy-2-methylvalerate (3H2MV) from mixed culture enriched by valerate-dominant hydrolysate was evaluated in this study. After long-term enrichment, the culture showed strong ability to synthesize 3HV and 3H2MV, even with acetate-dominant substrate. The ultilization of single or mixed iso-/n-valerate by the enriched culture showed that the mixture of iso-valerate and n-valerate was more efficient substrate than any single in terms of balancing microbial growth and PHAs synthesis. Besides, through comparing the kinetics and stoichiometry of the tests supplying valerate and propionate, the enriched culture with equivalent valerate and propionate (1:1 molar ratio) exhibited superior PHAs production performances to pure valerate or propionate, attaining more than 70 mol% of 3HV and 3H2MV. The above findings reveal that valerate-dominant hydrolysate is a kind of suitable substrate to enrich PHAs producing culture with great capability to synthesize 3HV and 3H2MV monomers, thus improving product properties than pure poly(3-hydroxybutyrate) (P3HB); also 3HV and 3H2MV production behaviors can be regulated by the type of odd-carbon VFAs in the substrate.
Online control of DNBF was studied in the pilot-scale and full-scale experiments.
DNBF was controlled by the online monitored effluent nitrate and turbidity.
The effluent nitrate lower than 3 mg·L−1 and saving 18% of carbon were both achieved.
Denitrifying biofilter (DNBF) is widely used for advanced nitrogen removal in the reclaimed wastewater treatment plants (RWWTPs). Manual control of DNBF easily led to unstable process performance and high cost. Consequently, there is a need to automatic control of two decisive operational processes, carbon dosage and backwash, in DNBF. In this study, online control of DNBF was investigated in the pilot-scale DNBF (600 m3·d−1), and then applied in the full-scale DNBF (10 × 104 m3·d−1). A novel simple online control strategy for carbon dosage with the effluent nitrate as the sole control parameter was designed and tested in the pilot-scale DNBF. Backwash operation was optimized based on the backwash control strategy using turbidity as control parameter. Using the integrated control strategy, in the pilot-scale DNBF, highly efficient nitrate removal with effluent TN level lower than 3 mg·L−1 was achieved and DNBF was not clogged any more. The online control strategy for carbon dosage was successfully applied in a RWWTP. Using the online control strategy, the effluent nitrate concentration was controlled relatively stable and carbon dosage was saved for 18%.
CNSBD can be used as a fuel without any modification in existing CI engine.
Pentanol reduces HC, CO, NOx and Smoke emissions significantly.
New and next generation alternative fuel is employed.
Blending of CNSBD with pentanol resulted in no separation of phases and found miscible.
This work investigates the effect of adding pentanol with biodiesel derived from cashew nut shell on its emissions characteristics is conducted in stationery diesel engine. The main purpose of this work is intended to reduce the emissions by fuelling biodiesel derived from cashew nut shell and the pentanol blends. Cashew nut shell biodiesel is prepared by transesterification process. Oxygenated additive used in the work is Pentanol. The experiment is conducted using four test fuels such as, biodiesel derived from cashew nut shell (CNSBD), a fuel containing 90% cashew nut shell biodiesel and 10% pentanol (CNSBD90P10), a fuel containing 80% cashew nut shell biodiesel and 20% pentanol (CNSBD80P20) and neat diesel. Experimental work concluded that by adding 10% of pentanol to cashew nut shell biodiesel 10.1%, 2.6%, 5.1% and 2.1%reduction in CO, HC, NOx and Smoke emissions were observed respectively. Further by fueling with these blends, no modifications in engines were required.
Mercury enrichment in response to elevated atmospheric mercury concentrations in the organs of rape (Brassica napus) was investigated.
Elevated soil mercury content had significant impact on mercury accumulation in rape stems, roots, seeds and seed coats.
Leaf mercury in the leaves was mostly affected by atmospheric input while the stems were mostly affected by soil concentrations.
Mercury in the aboveground plant tissue mainly derived from atmospheric absorption, and atmospheric mercury absorption in leaves was higher than that in the stems.
Mercury enrichment in response to elevated atmospheric mercury concentrations in the organs of rape (Brassica napus) was investigated using an open top chamber fumigation experiment and a soil mercury enriched cultivation experiment. Results indicate that the mercury concentration in leaves and stems showed a significant variation under different concentrations of mercury in atmospheric and soil experiments while the concentration of mercury in roots, seeds and seed coats showed no significant variation under different atmospheric mercury concentrations. Using the function relation established by the experiment, results for atmospheric mercury sources in rape field biomass showed that atmospheric sources accounted for at least 81.81% of mercury in rape leaves and 32.29% of mercury in the stems. Therefore, mercury in the aboveground biomass predominantly derives from the absorption of atmospheric mercury.
Distribution and behavior of arsenic in wetland are summarized.
Macro-scale and micro-scale processes in wetland are reviewed.
Microbes act as the switch in determining wetland as a source or sink of arsenic.
Environmental factors affecting arsenic microbial biotransformation are summarized.
Arsenic (As) is a pervasive environmental toxin and carcinogenic metalloid. It ranks at the top of the US priority List of Hazardous Substances and causes worldwide human health problems. Wetlands, including natural and artificial ecosystems (i.e. paddy soils) are highly susceptible to As enrichment; acting not only as repositories for water but a host of other elemental/chemical moieties. While macro-scale processes (physical and geological) supply As to wetlands, it is the micro-scale biogeochemistry that regulates the fluxes of As and other trace elements from the semi-terrestrial to neighboring plant/aquatic/atmospheric compartments. Among these fine-scale events, microbial mediated As biotransformations contribute most to the element’s changing forms, acting as the ‘switch’ in defining a wetland as either a source or sink of As. Much of our understanding of these important microbial catalyzed reactions follows relatively recent scientific discoveries. Here we document some of these key advances, with focuses on the implications that wetlands and their microbial mediated transformation pathways have on the global As cycle, the chemistries of microbial mediated As oxidation, reduction and methylation, and future research priorities areas.