COST EFFECTIVE ARSENIC REDUCTIONS IN PRIVATE WELL WATER IN MAINE1

ABSTRACT: This study was undertaken to investigate the cost effectiveness of selected arsenic avoidance methods. Annual costs of reverse osmosis (RO), activated alumina (AA), bottled water, and rented and purchased water coolers for various household sizes in Maine were compared. Relative ranking of systems shows that RO ($411 annually) is the most cost effective, followed by AA ($518) and one‐gallon jugs of water ($321 to $1,285), respectively, for households larger than one person. One‐gallon jugs ($321) followed by 2.5‐gallon jugs ($358) of water were found to be the most cost effective for households of one person or for households with arsenic III concentrations of 0.02 to 0.06 mg/L and arsenic V concentrations of 0.08 to 1.0 mg/L. Point‐of‐entry systems and water coolers were not found to be cost effective under any of the study's conditions. The research reported here will help states make more definitive treatment recommendations to households regarding the cost effectiveness of alternative treatment systems to reduce arsenic concentrations below 0.01 mg/L. While arsenic removal technologies are improving, which enhances removal rates and reduces costs, the major insights from this analysis appear to be reinforced by technological improvements.     

Synthesis of hydrogarnet from molten slag and its hydrogen chloride fixation performance at high temperature

Hydrogarnet was synthesized hydrothermally below 200°C using molten slag obtained from municipal solid waste. For comparison, it was also synthesized using pure-phase CaO–Al₂O₃–SiO₂–H₂O, as reported previously. The structural and textural properties of this material were investigated using various analytical and spectroscopic techniques such as X-ray diffraction, X-ray fluorescence spectrometry, atomic absorption spectrometry (AAS), thermogravimetry/differential thermal analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The Cl⁻ fixation ability of hydrogarnet was investigated in the temperature range 500–800°C in a fixed-bed flow reactor using a HCl concentration (1000 p.p.m.v.) similar to that of incinerator exhaust gas. Under these experimental conditions, the hydrogarnet was capable of reducing the HCl gas level to less than 1 p.p.m.v. Analysis of the spent catalyst revealed that the hydrogarnet was being transformed into wadalite and CaCl₂ at high temperatures. The elution test for chromium ions in hydrogarnet obtained from slag was also used, and it was found that chromium ions were not eluted from hydrogarnet. Received: January 27, 2001 / Accepted: October 11, 2001     

石化废水脱氮技术现状分析

针对石化废水脱氮的现有技术进行归纳,并对各种方法的优缺点进行了对比分析,探讨了目前石化废水的脱氮技术现状和发展趋势。结论是:目前还没有一种通用的方法能处理所有氨氮废水,必须针对不同废水选择不同的技术及工艺。为了更有效地处理废水,应联合使用多种方法和工艺,这已是目前废水处理的一种趋势。     

垃圾场渗出污水厌氧处理的可行性研究

采用血清瓶静态试验法研究了垃圾渗出污水的厌氧处理的可行性。试验表明:垃圾渗出污水对厌氧发酵微生物无抑制作用,有良好的厌氧降解性,产气率为0.321/g·COD,污水中的大部份有机物都能被厌氧消化,COD_cr去除率为78.2%,发酵过程中还能获得能源——沼气。具有良好的应用前景。     

EVALUATION OF CURRENT TECHNIQUES FOR NUTRIENT REMOVAL FROM WASTEWATERS1

ABSTRACT. A comprehensive evaluation of current techniques for nutrients, nitrogen and phosphorus, removal from wastewaters was conducted by the author under a research project supported by the Office of Water Resources Research, Department of the Interior. The object of this study was to compile and evaluate, under one cover, the available information on current techniques for removing nutrients from wastewaters with emphasis on type of treatment (physical, chemical, biological, or any combination); economics (capital and operating costs); efficiencies, and applications. Due to space limitations, only a brief summary of this work is presented in this paper. A copy of the completion report may be obtained from the author.     

石灰-聚铁法处理硫酸厂废水的研究

对各种处理硫酸厂废水的方法者了探讨,选择了以百石灰和聚合硫酸铁为药剂去除废水中砷,硫等污染物的方法。该法工艺简单,混凝剂投加量少,运行费用低,处理后的废水可达到排放标准。     

测定单个粒子的薄膜法及其应用

本文介绍改进后的薄膜法,主要是形态分析法和复合薄膜法。它们都是基于粒子和薄膜反应生成物的形态特征通过电镜来确定粒子成分的。前者可以检测单个酸性粒子,检出下限为７ ×１０－ １９ｇ;后者能同时检出一个粒子中所含的ＮＯ－３ 和ＳＯ２ －４ ,检出下限分别为３ ×１０－ １５ｇ 和７ ×１０－ １８ｇ。利用该方法对广州大气粒子进行了观察,结果表明改进后的薄膜法完全适用于对单个粒子的观察和测定。     

洗涤剂中的磷对环境的影响及对策的探讨

本文介绍了关于洗涤剂中磷对环境影响的两种典型观点和解决的办法,并从经济和环境的角度进行全面的分析,得出合理的结论和建议。     

Tree Leaf Biomarkers for Atmospheric Nitrogen Deposition

The aim of this paper was to investigate the effects of nitrogen (N) deposition on tree N cycling and identify potential biomarkers forNdeposition. Between April and October 2002 extensive fieldwork was undertaken at Mardley Heath in Hertfordshire. This woodland, located adjacent to the A1(M) motorway, is exposed to high levels of atmospheric nitrogen oxides from the traffic. Measurements of ¹⁵N, in vivo nitrate reductase (NR) activity, tissue, xylem and surface nitrate concentrations as well as N concentration and growth were made along a 700-m transect at 90° to the motorway. The ¹⁵N data show that oxidised N from the road traffic is taken up by nearby trees and is incorporated into plant tissues. Our measurements of NR activities suggest elevated rates close to the motorway. However, xylem sap, leaf tissue and leaf surface nitrate concentrations showed no differences between the roadside location and the most distant sampling point from the motorway. Taken together the ¹⁵N and nitrate reductase data suggest uptake and assimilation of N through the foliage.We conclude that for this lowland deciduouswoodland, tissue, xylem and surface measurements of nitrate are unreliable biomarkers for N deposition whereas ¹⁵N, growth measurements and integrated seasonal NR might be useful. The results also point to the benefit of roadside tree planting to screen pollution from motor vehicles.