FACTORS THAT AFFECT ACTIVATED SLUDGE PHOSPHATE RELEASE1

The activated sludge process can remove significant amounts of phosphorus from sewage, but the removal efficiency is usually significantly reduced by the release of phosphate back to solution during subsequent treatment steps. This research presents a study of soluble phosphate release from activated sludge with emphasis on defining the factors that affect such release and the actual release mechanisms. Laboratory units were used for experimental purposes. The experiments were designed to study the relationship between soluble phosphate release and various environmental factors such as redox potential (ORP), dissolved oxygen (DO), pH, solids concentration, solids destruction, and sulfate salt addition. The effect of substrate utilization on phosphate uptake and the relationship between uptake characteristics and subsequent phosphate release were also studied. The results show that some phosphate storage occurs during aerobic substrate utilization. Following substrate utilization, activated sludge phosphate release is directly related to the amount of biological stress the organisms are subjected to, and the mechanism of release is primarily cell lysis. The phosphate released per unit sludge under anoxic conditions is relatively constant. Under normal environmental conditions, neither ORP or pH change have a significant affect on phosphate release.     

环境水样阴离子表面活性剂光度测定法

本文通过实验研究,提出了对河水及生活废水阴离子表面活性剂的水相直接测定方法,此方法具有简便、快速的特点,且有良好的准确性和再现性。     

省沽油中硒含量及其测定方法研究

采用消化液硝酸／高氯酸消解法、硝酸-硫酸消解法和微波消解方法消化省沽油，用原子吸收分光光度法测定硒（Se）含量。比较了3种消解方法在测定省沽油中的硒含量。发现微波消解法测定野生省沽油（干菜）中Se含量准确性好、时间段效率高、对环境污染少、操作简单。     

微波消解法快速测定渗滤液化学需氧量

针对国标回流法测定化学需氧量消耗时间长,分析费用高等不足,研究了微波消解法测定垃圾渗滤液的试验方法.通过微波消解功率、消解时间、催化剂用量等试验,确定了微波消解测定渗滤液CODCr的最佳条件.该方法具有省时间、省试剂、准确度高等优点.     

军用浸渍活性炭中银含量测定方法——火焰原子吸收分光光度法

本研究建立了一种用空气-乙炔火焰原子吸收分光光度法测定浸渍活性炭中银含量的分析方法，对酸介质浓度、共存元素的干扰进行了探讨，在0—1．0ml沪范围内，银含量与吸光度呈线性关系，相关系数为0．9999。对09型浸渍活性炭标准物质进行测定，测定结果的相对标准偏差为0．191％（n=10），加标回收率为97．5％-101．4％。     

EVALUATION OF COPPER ACCUMULATION IN PART OF THE CALIFORNIA AQUEDUCT1

ABSTRACT: Copper sulfate has been used extensively in the California Aqueduct to control phytoplankton and the alga Cladophora. Since 1969 more than 250,000 pounds of copper sulfate has been added to a part of the aqueduct. Although copper sulfate is effective in controlling algae, copper tends to accumulate in the system in which it is applied. Samples of water, biota including plants, clams, and snails, as well as sediment were analyzed for copper. Results of these analyses showed that copper concentrations in the water, with three exceptions, were less than 10 micrograms per litre. Samples of plant tissue showed a 198 percent increase in copper concentration in the treated reach of the aqueduct, and clam tissue showed a 68 percent increase. Snails in the treated reach had 77 percent more copper than in the untreated reach whereas copper concentrations in the sediment doubled. None of the concentrations found are considered to be harmful to the biota.     

Method of Testing the Penetration of Acid Solutions Through Safety Gloves

Because they cause burns that are difficult to heal, acids are dangerous, and steps should be taken to ensure that the human skin does not come into contact with them. For this purpose safety gloves are generally used by workers who have to handle acids. Such gloves need to be tested to ensure that they are acid resistant. Standard EN 374 (European Committee for Standardization [CEN], 1993c) specifies a method of testing the permeation of liquid chemicals, on a molecular level, through glove material, but it may be difficult to ensure the fitness of the joints of a two-compartment cell, when gloves are lined with jersey. To deal with this a simple pH-meter method to test the permeation of acid and alkali solutions through safety gloves has been developed. The permeation of H₂S0₄, HCI, HN0₃, and CH₃COOH through gloves made from neoprene, nitrile, and PVC was tested. This method seems to be simple and economical.     

三烧溴化锂集中制冷空调系统改建设计

武钢三烧区域改建了二台大连三洋蒸汽型双效溴化锂吸收式制冷机。叙述了该改建项目的主机选型、参数选定、设计特点等。     

Increase in Hair Lead, but not Blood Lead Content of Occupationally-Exposed Workers

This study attempted to investigate whether increased hair lead concentrations due to environmental exposure are accompanied by parallel increases in blood lead concentrations. A sample set consisting of both occupationally-exposed individuals and persons from the general population was investigated. The lead content of scalp and pubic hair from the general population (n=189), traffic police personnel (n=27) and battery workers (n=22) were analysed. The hair samples were taken from the nape of the neck by cutting 23 cm closest to the scalp and cleaned using a washing procedure developed in our laboratory. The effectiveness of the washing procedure was partly determined by examining the scanning electron micrographs of the hair samples. Venous samples of blood were taken from each volunteer's arm.The traffic police and battery plant operators sampled had significantly higher average scalp hair and pubic hair lead levels than the non occupationally-exposed general population. No significant differences were found between the blood lead values of these workers and the general population. Compared to the general population both occupationally-exposed groups had significantly more symptoms of lead toxicity.Lead particles were still observed on the hair shafts after the washing procedure. The amount of such lead contamination was difficult to quantify, the problem being further exacerbated by the difference in hair texture of the persons sampled. This exogenous contamination therefore detracts from the usefulness of hair as an indicator of lead exposure.