Thermal modeling,characterization, and enviro-economic investigations on inclined felt sheet solar distiller for seawater desalination

Environmental Science and Pollution Research - Sustainable desalination can be achieved by adopting renewable energy-based low-cost and low-impact desalting techniques. In this investigation,...     

The Flakt-Hydro process: flue gas desulfurisation by use of seawater

ABB's seawater scrubbing process (the Flakt-Hydro process) for flue gas desulfurisation has recently triggered much interest among power producers because of its simple operating principle and high reliability. The process uses seawater to absorb and neutralise sulfur dioxide in flue gases. The absorbed gas is oxidised and returned to the ocean in the form it originated in the first place, namely as dissolved sulfate salts. The process uses the seawater downstream of the power plant condensers. This paper gives an introduction to the basic principle of the process and presents some of the recent power plant applications, namely at the Paiton Private Power Project, Phase 1 (2 ∞ 670 Mwe) in Indonesia and at the Shenzhen West Power Plant, Unit 2 (300 MWe) in China.     

Treatment and desalination of domestic wastewater for water reuse in a four-chamber microbial desalination cell

Environmental Science and Pollution Research - Microbial desalination cells (MDCs) have been studied for contaminant removal from wastewater and salinity reduction in saline water. However, in an...     

Interactions between chloride and sulfate or silica removals using an advanced lime-aluminum softening process.

An advanced softening process called the ultra-high lime with aluminum process (UHLA) was initiated in this research. The UHLA process has the ability to remove sulfate, silica, and chloride from waters such as recycled cooling water and desalination brines. Furthermore, it can remove other scale-forming materials, such as calcium, magnesium, carbonate, and phosphate. The purpose of this paper is to study the interactions among chloride, sulfate, and silica in the UHLA process. Results of equilibrium experiments indicated that sulfate is preferentially removed over chloride. Final chloride concentration increased with increasing initial sulfate concentration. However, initial chloride concentration was found to have negligible effect on final sulfate concentration. Silica was found to have only a small effect on chloride removal.     

Economic feasibility of solar-powered reverse osmosis water desalination: a comparative systemic review

Environmental Science and Pollution Research - Due to disparities in the allocation of rainwater and drought, extreme exploitation of groundwater reservoirs has depleted water supplies in many...     

Interactions between chloride and sulfate or silica removals from wastewater using an advanced lime-aluminum softening process: equilibrium modeling.

Interactions among chloride, sulfate, and silica removals from recycled industrial wastewater using an ultra-high lime with aluminum process (UHLA) were studied. An equilibrium model that is able to accurately predict the chemical behavior and interactions between chloride and sulfate or silica with UHLA at various initial conditions and chemical reagents was developed. X-ray diffraction (XRD) analysis was conducted to identify the precipitated solids formed in the UHLA process. Model predictions indicated that simultaneous removal of sulfate and chloride can be best described by the formation of a solid solution containing calcium chloroaluminate, calcium sulfoaluminate (ettringite), calcium monosulfate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. However, simultaneous removal of silica and chloride can be best described by precipitation of calcium silicate and calcium aluminosilicate in addition to a solid solution containing calcium chloroaluminate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. The XRD results indicated the presence of the same solids assumed by the equilibrium model.     

超滤与电渗析联用降低油田采出水矿化度中试试验研究

以大庆油田常规处理后的油田采出水为处理对象，建立日产水300t的超滤预处理和电渗析脱盐处理中试试验装置。考察该工艺所能达到的技术经济指标，掌握放大规律，为万吨级工业装置和系统的设计提供基础数据。经过3000h长时间连续试运行，系统出水水质稳定，出水浊度低于1．0NTU，悬浮物和含油量低于1．00mg／L，矿化度低于1000mg／L，水质完全满足配制聚合物用水要求，证明采用处理后的油田采出水代替清水作为聚合物驱用水是可行的。     

O3／UV预处理磺酰脲类除草剂生产废水的研究

采用O3／UV工艺预处理磺酰脲类除草剂生产废水,考察了初始pH值、臭氧投量、叔丁醇投加等因素对废水处理效果的影响,并初步探讨了该工艺处理废水的反应机理。实验结果表明,在废水初始pH为13．59和臭氧投量为65．08mg／min的条件下,预处理80min后废水COD去除率达63．47％,BOD5／COD由0．03提高至0．56,EC50从11％提高至55％。随着叔丁醇浓度的增加,废水COD去除率明显降低,证明该反应体系有·OH存在;体系中加入MnO2后废水COD去除率下降了16％,氧化效率明显下降,证明该反应体系内中间产物HO2O在O3／UV降解有机废水过程中起到了重要的作用。     

Wetfall Deposition and Precipitation Chemistry for a Central Appalachian Forest

Abstract

Although extensive research on acidic deposition has been directed toward spruce-fir forests, less research has been done on the impacts of air pollution on eastern montane hardwood forests. The purpose of this study was to describe precipitation chemistry for several Appalachian hardwood forest sites at or near the Fernow Experimental Forest (FEF) to assess the potential for problems associated with acidic deposition. Emphasis was placed on seasonal patterns of ionic concentrations (H+, Ca++, NH4+; NO3-, and SO4=) and spatial variability of ionic concentrations and deposition among sites. Seasonal patterns of most ions showed highest concentrations during the summer months and deposition of H+ was especially pronounced during this time. Deposition of all ions was generally greater (related to greater precipitation) at three montane forested sample sites compared to a nonforested riverbottom site. Precipitation chemistry at FEF was similar to other sites throughout the eastern United States and contrasted sharply with mid-western and western sites. Eastern sites, including means for FEF sites, were uniformly 3-4 times higher in H+ and SO4= concentration than the mid-western and western sites. Precipitation at FEF was chronically acidic, more so during the growing season, and highest at higher elevations where environmental stresses can be most severe. Furthermore, there were occasional large discrepancies between the low-elevation site and the higher-elevation forested sites for precipitation chemistry and acidic deposition. These results suggest that synoptic-scale (network) data may greatly underestimate the pollutant conditions to which highelevation forest trees are exposed, since network data rarely take elevation into account and typically are based on annual ionic concentration and deposition means that may be considerably lower than those of the growing season.     

Biological denitrification in a closed seawater system

Build-up of high nitrate concentrations in closed seawater systems where primary productivity is undesirable and water changes are impractical presents unique problems. Nitrate concentration in Ocean Tank at the New Jersey State Aquarium reached 9500 microM after 6 years of operation. A biological denitrification system was installed in 1998 and nitrate concentration in the aquarium decreased to 7000 microM within the first 100 days of operation. The system offers additional benefits by increasing the pH and alkalinity of seawater and providing a reducing environment to balance the oxidizing disinfection environment in the aquarium. The initial performance of the denitrification system was monitored and two semi-empirical models were developed: one based on the actual methanol additions, and another based on the daily amounts of nitrogen gas removed. The first model predicts a net nitrate decrease of 39 microM/day in the aquarium. The second model predicts a net decrease of 25 microM/day, in good agreement with the empirical value of 23 microM/day. This indicates that nitrogen gas removal is the controlling factor during denitrification in this facility, and the second model can be used to predict and optimize the operation of the system.     

Mercury distribution in seawater discharged from a coal-fired power plant equipped with a seawater flue gas desulfurization system

Background and purpose  

More and more coal-fired power plants equipped with seawater flue gas desulfurization systems have been built in coastal areas. They release large amount of mercury (Hg)-containing waste seawater into the adjacent seas. However, very limited impact studies have been carried out. Our research targeted the distribution of Hg in the seawater, sediment, biota, and atmosphere, and its environmental transportation.     

Effects of solar geometry and operation period on stability of solar desalination systems: a review

Environmental Science and Pollution Research - The sun is the primary source of life on the earth. The heating effect of the sun provides a more fruitful environment for mankind. In addition, solar...     

A semipermeable membrane equilibrator for halomethanes in seawater

An equilibrator for sampling the partial pressures of halomethanes in seawater was designed and built, incorporating semipermeable membrane tubing to carry the gas phase. The equilibrator was tested for its ability to equilibrate chloromethane, bromomethane, iodomethane, and CFC-11. The residence time required for these halomethanes to equilibrate in the tubing (30 to 60 s) was determined experimentally. In a laboratory test, concentrations calculated from equilibrator measurements and based on published solubility values were found to differ by 6% to 16% from concentrations measured with a purge-and-trap apparatus, but uncertainties in the solubility values are likely to contribute significantly to the differences. In a comparison at sea, no significant difference was found between the semipermeable membrane equilibrator and another, more conventional equilibrator, except a 1.3% difference for CFC-11. This study demonstrates the feasibility of using semipermeable membranes in this and related applications.     

The Effects of Precipitation on Aquatic and Terrestrial Ecosystems: A Proposed Precipitation Chemistry Network

Precipitation is one of the most important factors determining the nature and productivity of terrestrial and aquatic ecosystems. Detailed historical and contemporary records are available indicating the amount of water deposited at thousands of locations throughout the world. Comparatively, however, knowledge of the changing chemistry of precipitation has developed only recently and is still very fragmentary. Our present ignorance of the total impact of changes in precipitation quality on the productivity and stability of ecosystems is especially profound. This paper has a fourfold purpose: (1) to describe the myriad of trace chemical constituents transferred from the atmosphere into the biosphere of the earth; (2) to define the range of beneficial and injurious ecological effects of perturbations in atmospheric deposition; (3) to explain the concepts of sensitive areas, life stages, and life forms; and (4) to describe briefly plans for a National Deposition Network and associated research on the terrestrial and aquatic ecosystems of the United States.     

Electro-Fenton pretreatment for the improvement of tylosin biodegradability

The feasibility of an electro-Fenton process to treat tylosin (TYL), a non-biodegradable antibiotic, was examined in a discontinuous electrochemical cell with divided cathodic and anodic compartments. Only 15 min electrolysis was needed for total tylosin degradation using a carbon felt cathode and a platinum anode; while 6 h electrolysis was needed to achieve high oxidation and mineralization yields, 96 and 88 % respectively. Biodegradability improvement was shown since BOD₅/COD increased from 0 initially to 0.6 after 6 h electrolysis (for 100 mg L^?1 initial TYL). With the aim of combining electro-Fenton with a biological treatment, an oxidation time in the range 2 to 4 h has been however considered. Results of AOS (average oxidation state) and COD/TOC suggested that the pretreatment could be stopped after 2 h rather than 4 h; while in the same time, the increase of biodegradability between 2 and 4 h suggested that this latter duration seemed more appropriate. In order to conclude, biological cultures have been therefore carried out for various electrolysis times. TYL solutions electrolyzed during 2 and 4 h were then treated with activated sludge during 25 days, showing 57 and 67 % total organic carbon (TOC) removal, respectively, namely 77 and 88 % overall TOC removal if both processes were considered. Activated sludge cultures appeared, therefore, in agreement with the assessment made from the analysis of physico-chemical parameters (AOS and COD/TOC), since the gain in terms of mineralization expected from increasing electrolysis duration appeared too low to balance the additional energy consumption.     

Laboratory and field evaluation of a pretreatment system for removing organics from produced water

Co-produced water from the oil and gas industry accounts for a significant waste stream in the United States. This "produced water" is characterized by saline water containing a variety of pollutants, including water soluble and immiscible organics and many inorganic species. To reuse produced water, removal of both the inorganic dissolved solids and organic compounds is necessary. In this research, the effectiveness of a pretreatment system consisting of surfactant modified zeolite (SMZ) adsorption followed by a membrane bioreactor (MBR) was evaluated for simultaneous removal of carboxylates and hazardous substances, such as benzene, toluene, ethylbenzene, and xylenes (BTEX) from saline-produced water. A laboratory-scale MBR, operated at a 9.6-hour hydraulic residence time, degraded 92% of the carboxylates present in synthetic produced water. When BTEX was introduced simultaneously to the MBR system with the carboxylates, the system achieved 80 to 95% removal of BTEX via biodegradation. These results suggest that simultaneous biodegradation of both BTEX and carboxylate constituents found in produced water is possible. A field test conducted at a produced water disposal facility in Farmington, New Mexico confirmed the laboratory-scale results for the MBR and demonstrated enhanced removal of BTEX using a treatment train consisting of SMZ columns followed by the MBR. While most of the BTEX constituents of the produced water adsorbed onto the SMZ adsorption system, approximately 95% of the BTEX that penetrated the SMZ and entered the MBR was biodegraded in the MBR. Removal rates of acetate (influent concentrations of 120 to 170 mg/L) ranged from 91 to 100%, and total organic carbon (influent concentrations as high as 580 mg/L) ranged from 74 to 92%, respectively. Organic removal in the MBR was accomplished at a low biomass concentration of 1 g/L throughout the field trial. While the transmembrane pressure during the laboratory-scale tests was well-controlled, it rose substantially during the field test, where no pH control was implemented. The results suggest that pretreatment with an SMZ/MBR system can provide substantial removal of organic compounds present in produced water, a necessary first step for many water-reuse applications.     

Biofiltration pretreatment for reverse osmosis (RO) membrane in a water reclamation system

Biofouling control is considered as a major challenge in operating membrane systems. A lab-scale RO system was setup at a local water reclamation plant to study the feasibility of using biofiltration as a pretreatment process to control the biofouling. The biological activity in the RO system (feed, product, reject streams) was tested using the standard serial dilution plating technique. Operational parameters such as differential pressure (DP) and permeate flowrate of the system were also monitored. Effects of biofilter on AOC and DOC removals were investigated. Biofiltration was found to be a viable way of assimilable organic carbon (AOC) and dissolved organic carbon (DOC) removals, with removal efficiencies of 40-49% and 35-45% at an empty bed contact time (EBCT) of 30 min. It was also found that using the biofiltration as a pretreatment reduced the rate of biofouling. It took only about 72 h for biofouling to have a significant impact on the performance of the RO membrane, when the system was operated without using biofiltration as pretreatment. There was, however, a five times increase in operational length to more than 300 h when biofiltration was used. This study presented the suitability of the biofilter as an economical and simple way of biofouling control for RO membrane.     

A holistic study on geothermal and solar water desalination system for sustainable development

Environmental Science and Pollution Research - This paper shows the comparison of the various conventional technologies used for desalination and the advantages of using renewable energy such as...     

新型的脱氮工艺--SHARON工艺

SHARON是一种用来处理高浓度、低碳氮比含氨废水的新型脱氮工艺。该工艺根据亚硝酸菌和硝酸菌的不同生长条件,通过控制反应器的水力停留时间和pH,使亚硝酸菌成为反应器的优势菌属,从而将氨氮的氧化控制在亚硝化阶段,随后再进行反硝化。与传统脱氮工艺相比,SHARON工艺具有流程简单、脱氮速率快、投资和运行费用低等优点。     

用于处理冲厕海水的固定化生物硅藻土小球的制备

选用聚乙烯醇（PVA）和海藻酸钠（SA）混合物作为包埋载体,对筛选出的耐盐复合菌群固定化制备方法进行了研究。通过正交实验分别研究了包埋载体不同配比、包菌量、硅藻土投加量和交联时间对固定化生物硅藻土小球的性能及其对冲厕污水中COD去除效果的影响。研究结果表明,固定化生物硅藻土小球最佳包埋条件是：聚乙烯醇9％,海藻酸钠0．5％,包菌量l：1,硅藻土20g／L,交联时间为24h。在该条件下,小球成球效果较好,机械强度高,对海水冲厕污水中COD的去除率达86．95％。