Effect of molecular characteristics on the formation of nitrosamines during chlor(am)ination of phenylurea herbicides.

The objective of this study was to investigate the formation of different nitrosamines during chlorination or chloramination (chlor(am)ination) of five phenylurea herbicides (fluometuron, diuron, linuron, metobromuron, and propanil), with the effects of disinfection approaches, additional inorganic nitrogen, and reaction pH being studied. By analyzing six nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) formation was observed. The dimethylamine functional group was the key to determining whether a particular phenylurea herbicide was an important nitrosamine precursor, as the NDMA conversion ratio was much higher.

Comparing removal of trace organic compounds and assimilable organic carbon (AOC) at advanced and traditional water treatment plants.

Stability of drinking water can be indicated by the assimilable organic carbon (AOC). This AOC value represents the regrowth capacity of microorganisms and has large impacts on the quality of drinking water in a distribution system. With respect to the effectiveness of traditional and advanced processing methods in removing trace organic compounds (including TOC, DOC, UV(254), and AOC) from water, experimental results indicate that the removal rate of AOC at the Cheng Ching Lake water treatment plant (which utilizes advanced water treatment processes, and is hereinafter referred to as CCLWTP) is 54%, while the removal rate of AOC at the Gong Yuan water treatment plant (which uses traditional water treatment processes, and is hereinafter referred to as GYWTP) is 36%.

Variation and removal efficiency of assimilable organic carbon (AOC) in an advanced water treatment system.

This study investigates the microorganism growth indicator and determines the assimilable organic carbon (AOC) content at the Cheng-Ching Lake Advanced Water Treatment Plant (CCLAWTP) in Kaohsiung, Taiwan. Notably, AOC is associated with the biological stability within the water distribution network and has garnered considerable attention in the environmental engineering field in recent years. Water samples were collected from the effluent of each unit in CCLAWTP once monthly during December 2008 to November 2009.

Treatment of VOCs with molecular sieve catalysts in regenerative catalytic oxidizer.

This work prepares molecular sieve catalysts with various metal species and various metal weight loadings by impregnation, and then screens them in a catalytic combustion system. The current study further investigates the molecular sieve catalyst in an RCO system after it performed well in combustion efficiency. This work tests its performances in terms of CO(2) yield, pressure drop, the difference between temperatures of the inlet and outlet gases (T(d)), and thermal recovery efficiency (TRE), with various operational conditions.

Recycling of Cu powder from industrial sludge by combined acid leaching, chemical exchange and ferrite process.

A method in combination of acid leaching, chemical exchange and ferrite process was applied to recycle copper and confer higher chemical stability to the sludge generated from etching process in printed circuit board industry. Ninety-five percent copper could be recycled in the form of powder from the sludge. Moreover, not only the wastewater after chemical exchange can be treated to fulfill the effluent standard, but also the sludge can satisfy the toxicity characteristic leaching procedure (TCLP) limits made by Taiwan's environmental protection administration.

Effective removal of disinfection by-products and assimilable organic carbon: an advanced water treatment system.

The purpose of this work is to investigate an advanced water treatment system changes on disinfects by-products (DBPs) precursors removal efficiencies of treatment plant and associated trihalomethanes (THMs) and haloacetic acids (HAA(5)) formation and assimilable organic carbon (AOC) in reduction from raw water through finished water of Fong-shan Water Treatment Plant (FSWTP) in Kaohsiung City, Taiwan. Drinking water samples were collected from an advanced water treatment plant during March-October 2008. In the formation of DBPs, advanced water treatment processes efficiently removed THMs and HAA(5).

Treatment of printed circuit board industrial wastewater by Ferrite process combined with Fenton method.

Printed circuit board wastewater typically contains organics and metal ions. The study explored the feasibility of a sequential procedure, FFP (the combination of the Fenton method and the Ferrite process), for treating printed circuit board wastewater, and established the optimum parameters for it. The analytical results showed that the proper pH level was 2 for Fenton oxidation, and the appropriate H2O2 dosing type was batch dosing.

Generation of disinfection by-products (DBPs) at two advanced water treatment plants.

A sampling program was conducted to investigate the formation of disinfection by-products (DBPs) and dissolved organic carbon (DOC) at two advanced water treatment plants in Kaohsiung City, Taiwan. The results in this study can be used as a reference for the operational control of water treatment plants and the setting of regulations in Taiwan. Samples of drinking water were collected from two advanced water treatment plants from June 2007 to April 2008.

Assessing the performance of wastewater treatment with the combination of Fenton and ferrite process.

Industrial wastewater typically contains various metal ions. Traditional metal ion treatment processes such as chemical precipitation generate large volumes of toxic sludge which needs to be further solidified or disposed of. The ferrite process (FP), which is another effective approach of treating metal ion-containing wastewater, can crystallize metal ions into ferrites; the sludge easily precipitates, is stable and can be recycling.

Assessing the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units.

Wastewater reuse can significantly reduce environmental pollution and save the water sources. The study selected Cheng-Ching Lake water treatment plant in southern Taiwan to discuss the feasibility of wastewater recycling and treatment efficiency of wastewater treatment units. The treatment units of this plant include wastewater basin, sedimentation basin, sludge thickener and sludge dewatering facility.

Assessing water quality of drinking water distribution system in the South Taiwan.

This investigation conducted a full-scale survey the drinking water distribution system in Kaohsiung city, Taiwan. The aim was to investigate whether the distribution system was capable of maintaining high water quality from the water treatment facilities through to the end user. The results showed that the distribution system can maintain high water quality, except for suitable chlorine residuals.

Influence of alkalinity, hardness and dissolved solids on drinking water taste: A case study of consumer satisfaction.

Two surveys of consumer satisfaction with drinking water conducted by Taiwan Water Supply Corp. are presented in this study. The study results show that although a lot of money was invested to modify traditional treatment processes, over 60% of local residents still avoided drinking tap water.

Incinerating volatile organic compounds with ferrospinel catalyst MnFe2O4: an example with isopropyl alcohol.

This paper concerns the incineration of isopropyl alcohol (IPA) using the ferrospinel catalyst MnFe2O4. It covers the preparation of the ferrospinel catalyst, the screening of catalytic activity, catalytic incineration testing, and 72-hr decay testing of the catalyst. The experimental results of catalyst screening reveal that the Mn/Fe catalyst is the best of five prepared catalysts (chromium/iron [Cr/Fe], manganese/iron [Mn/Fe], zinc/iron [Zn/Fe], nickel/iron [Ni/Fe], and pure magnetite [Fe3O4]).

Catalytic destruction of dichloromethane using perovskite-type oxide catalysts.

Dichloromethane (DCM, also known as methylene chloride [CH2Cl2]) is often present in industrial waste gas and is a valuable chemical product in the chemical industry. This study addresses the oxidation of airstreams that contain CH2Cl2 by catalytic oxidation in a tubular fixed-bed reactor over perovskite-type oxide catalysts. This work also considers how the concentration of influent CH2Cl2 (Co = 500-1000 ppm), the space velocity (GHSV = 5000-48,000 1/hr), the relative humidity (RH = 10-70%) and the concentration of oxygen (O2 = 5-21%) influence the operational stability and capacity for the removal of CH2Cl2.

Selective catalytic oxidation of ammonia over copper-cerium composite catalyst.

This work considers the oxidation of ammonia (NH3) by selective catalytic oxidation (SCO) over a copper (Cu)-cerium (Ce) composite catalyst at temperatures between 150 and 400 degrees C. A Cu-Ce composite catalyst was prepared by coprecipitation of copper nitrate and cerium nitrate at various molar concentrations. This study also considers how the concentration of influent NH3 (500-1000 ppm), the space velocity (72,000-110,000 hr(-1)), the relative humidity (12-18%) and the concentration of oxygen (4-20%) affect the operational stability and the capacity for removing NH3.

Removal of ammonia solutions used in catalytic wet oxidation processes.

Ammonia (NH(3)) is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological treatment is unfeasible. This investigation used aqueous solutions containing more of ammonia for catalytic liquid-phase oxidation in a trickle-bed reactor (TBR) based on Cu/La/Ce composite catalysts, prepared by co-precipitation of Cu(NO(3))(2), La(NO(3))(2), and Ce(NO(3))(3) at 7:2:1 molar concentrations.

Catalytic wet oxidation of 2,4-dichlorophenol solutions: activity of the manganese-cerium composite catalyst and biodegradability of the effluent stream.

Aqueous solutions containing 100 to 1000 mg/L of 2,4-dichlorophenol (2,4-DCP) were oxidized in an upflowing fixed-bed reactor in this study of manganese-cerium composite catalysts, which were prepared by the coprecipitation of both manganese nitrate and ceric nitrate at various molar concentrations. Results showed that 2,4-DCP conversion by wet oxidation in the presence of the manganese-cerium composite catalysts was a function of the molar ratio of the manganese-cerium catalyst. The kinetic behavior of 2,4-DCP oxidation with catalysis could be explained by using a zero-order rate expression.