Riley N. Kinman

Gas Enhancement Techniques in Landfill Simulators

Abstract Techniques to enhance landfill gas production from landfills were tested using 16 landfill simulators. These techniques included: accelerated moisture infiltration; elevated moisture content; leachate recycle; buffer (calcium carbonate), nutrient (ammonium phosphate), and/or sewage sludge additions; and elevated refuse temperature. Each test cell contained 380 kg (836 lb) of ground municipal solid waste. All simulators were constructed in February 1980. Reloading of some of the cells with the nutrient (ammonium phosphate), buffer (sodium carbonate) or anaerobic sewage sludge took place in January 1983. The simulators were operated until January 1985. Over this operating period, various physical and chemical parameters were measured to determine gas and leachate quantity and quality. Results indicated that sewage sludge additions, buffer additions, and nutrient additions were useful enhancement techniques of gas production from municipal solid waste. Moisture infiltration and elevated moisture content have shown some beneficial effects.

Dietary exposure of children in lead-laden environments.

Children are the most susceptible population to lead exposure because of three interacting factors; they have more opportunity for contact with lead sources due to their activities, lead absorption occurs more readily in a child compared to an adult, and the childs development is more vulnerable to lead than adults. Low levels of lead in the blood have been shown to cause adverse health effects; the level of concern for children is currently 10 µg/dl. The contribution of dietary exposure of lead to increased blood lead levels (PbB) is not well characterized. This study was conducted to measure potential dietary lead intakes of children 2 to 3 years of age who live in homes contaminated with environmental lead. Objectives were to estimate lead intakes for children consuming food in contaminated environments, recognizing unstructured eating patterns and to investigate if correlations exist between daily dietary exposure and measured PbB. Dietary exposure was evaluated by collecting samples that were typical of the foods the young children ate in their homes. A 24-h duplicate of all foods plus sentinel foods, i.e., individual items used to represent foods contaminated during handling, were collected from 48 children. Ten homes were revisited to obtain information on the variation in daily dietary intakes. Drinking water was evaluated both as part of the segregated beverage sample composite and by itself. Additional information collected included lead concentrations from hand wipes, floor wipes, and venous blood, and questionnaire responses from the caregiver on activities potentially related to exposure. Activities and hygiene practices of the children and contamination of foods in their environment influences total dietary intake. Estimated mean dietary intakes of lead (29.2 µg Pb/day) were more than three times the measured 24-h duplicate-diet levels (8.37 µg Pb/day), which were almost six times higher than current national estimates (1.40 µg Pb/day). Statistically significant correlations were observed between floor wipes and foods contacting contaminated surfaces, hand wipes and foods contacting contaminated hands and surfaces, and hand wipes and floor wipes. This study indicates that the dietary pathway of exposure to lead is impacted by eating activities of children living in lead-contaminated environments and that analysis of foods themselves is not enough to determine excess dietary exposures that are occurring.

Worker Exposure to Chlorinated Organic Compounds from the Activated-sludge Wastewater Treatment Process

The objective of this research was to investigate some of the potentially controlling factors influencing the atmospheric releases of volatile organic chlorinated compounds from the activated-sludge sewage treatment process. The field study was designed to evaluate the wastewater and airborne concentrations of six chlorinated compounds: hexachlorobicycloheptadiene (hex-BCH), heptachlorobicycloheptene (Hex-VCL), chlordene, chloroform (CHCl3), carbon tetrachloride (CCl4) and tetrachloroethylene (TCE). Analysis of samples consisted of saturating 5 mL aliquots with sodium chloride, extracting with an equal amount of petroleum ether (PE) and subsequent analysis using a gas chromatograph. The air samples collected on Chromsorb 102 were desorbed with 2 mL PE. The study revealed that the highest wastewater concentrations for the water-insoluble hex-BCH, hex-VCL and chlordene were found in the aeration basins, which suggests adsorption of these compounds to the biomass. The plant effluent wastewater concentrations were reduced because of airborne release and suspended solids separation in the clarifiers. In contrast, the wastewater concentrations for the more water-soluble CHCl3, CCl4 and TCE were significantly reduced in the aeration basins. This is because of aerial stripping at the grit-chamber weir. This study suggests that the water-insoluble compounds have prolonged aerial release from the aeration basins. The water-insoluble compounds adhere to the biomass, which is recycled through the plant. The aerial release of these water-insoluble compounds was enhanced by increased aeration rate but depressed by higher suspended solids concentrations.

Relationship between nine haloacetic acids with total organic halogens in different experimental conditions.

The effects of pH and bromide ion concentration on the formation of nine haloacetic acids (HAAs) and total organic halogens (TOX) in chlorinated drinking water have been evaluated. In an extensive study, the relationships of nine HAAs with TOX have been investigated. Honesty Significant Differences test (HSD) and ANOVA tests were used for the statistical analyses. The study determined the concentration range of nine HAAs as of a percentage of TOX at varying experimental conditions. Statistical analyses showed that the parameters pH and Br had significant effects on the formation of nine HAAs and TOX. This study also showed that brominated and mixed species of HAAs would be dominant in the presence of high bromide ion concentration which contributes a high percentage of the TOX. The results of this study could be used to set up a maximum contaminant level of TOX as a water quality standard for chlorination by-products.

Aerial organic chemical release from activated sludge

Abstract The objective of this study was to investigate some of the potentially controlling factors influencing the atmospheric release of volatile organic compounds from the activated-sludge sewage treatment process. A bench-scale aeration vessel was used to investigate the influence of aeration rate, suspended solids concentration and detergent concentration on the rate of stripping of hexa-chlorobicycloheptadiene (Hex-BCH) and chloroform from simulated wastewater. These compounds had previously been found to be released from an 80 mgd activated sludge wastewater treatment plant. First order kinetic decay was found for the stripping of Hex-BCH and chloroform. The influences of aeration rate, suspended solids concentration and detergent concentration on the release of Hex-BCH were each statistically significant. The increase in aeration rate appreciably enhanced the release of Hex-BCH, while increasing the concentration of suspended solids inhibited stripping. A linear relationship was found between detergent concentration and stripping rate. Aeration rate was the only significant variable influencing the release of chloroform. The results suggest that Hex-BCH is stripped from an adsorbed state and chloroform from a dissolved state.