Foppe B. DeWalle

Composition and variability of leachate from recent and aged areas within a municipal landfill

A leachate study was conducted at a large, operating, regional municipal solid waste (MSW) landfill near Seattle, Washington, to examine differences in composition and emission rates between old and new areas of the fill. The landfill began operation in 1966, was receiving approximately 2000 tpd of MSW and had 30×10 6 m 3 (∼12×10 6 tonnes) waste in place at the time of this study. The two areas studied had average ages of 3.7 and 16 years, and contained 5.7×10 6 and 2.04×10 6 tonnes of MSW, respectively. Variations in flow rate, total dissolved solids (TDS), chemical oxygen demand (COD), total organic carbon (TOC), Fe, and Mn were monitored over a 3-month period in the winter and spring of 1992. Increases in flow driven by precipitation caused gradually increasing leachate mass emissions from the aged fill. The rate of mass emission increase with increasing flow from the new fill was more than three times higher than that from the old fill. Leachate flow through the old fill appeared more channelized, resulting in diluting effects with increasing percolation. In leachate from the new fill concentrations were essentially independent of flow. Overall, mass emissions per unit waste mass in place decreased with increasing waste age for TDS and Mn, indicating that these components were leachable independent of degradation processes. Mass emissions per unit waste mass in place increased with increasing waste age for COD, TOC, and Fe, which typify components that increase in availability for leaching with increasing age and progressing stage of decomposition

Watershed use and Giardia cyst presence

Abstract The presence of Giardia in a heavily visited watershed in the Olympic Mountains was compared to that in an adjacent watershed having much lower human use. Also, statistical relationships between cyst presence and watershed use parameters were examined as indicators of potential causal relationships. The number of Giardia cysts found in water samples ranged from 0.2 100 l to 3 100 l and were highest in areas of high human use. A significantly higher prevalence of Giardia in selected animal species was observed in the heavily visited watershed. Statistically significant relationships were found between aqueous Giardia cyst concentrations and both the prevalence of Giardia in animals and the intensity of human use. Based on the water samples analyzed, a calculated median cyst concentration of 1 cyst per 20 l (0.05 cysts/l) can be expected in relatively pristine rivers.

Characterization of Major and Minor Organic Pollutants in Wastewaters from Coal Gasification Processes

Abstract In order to investigate the feasibility of anaerobic biological treatment for wastewaters generated from thermal gasification processes of coal, a characterization program was implemented whose major effort consisted in the elucidation of specific organic constituents contained in the wastewater. Solvent extraction in acid and base conditions followed by glass capillary gas chromatography in combination with several detectors (i.e., FID, NPD, and MS-DS) were employed for the investigation of major and minor “extractable” organic constituents. Direct aqueous injection on a polar glass capillary column (i.e., OV-351) was used for the major “nonsolvent extractable” organic constituents amenable to GC. The identity of 28 organic compounds was confirmed by comparison with pure standards. Phenol, the three cresol isomers, 5,5-dimethyl-hydantoin and 5-methyl,5-ethylhydantoin were identified as major wastewater constituents. Several substituted phenols (e.g., methyl, dimethyl, trimethyl, methylethyl, hyd...

Simple sample digestion of sewage and sludge for multi-element analysis

Abstract A simple digestion method of sewage, sludge, and other materials in sealed ampuls for multi‐element determination is reported. The sealed samples are digested in an autoclave at 125°C and 1.2 atmosphere pressure for one hour. In a single digestion both volatile and non‐volatile elements are recovered. Comparison of this method with conventional hot plate digestion using NBS reference materials, sewage, and sludge, shows equal or better recoveries of the metals in sealed ampuls. The method is not prone to metal contamination and can be used for large numbers of samples.

Concentration and removal efficiency of major and trace elements in municipal wastewater

Abstract Concentrations of P, Fe, Zn, Cu, Mn, Cr, Pb, Ni, Ag, Cd, As, Co, Hg, and Se in the influent and effluent of 25 sewage treatment systems in different metropolitan areas of the United States were measured. Attenuation of the concentrations of these elements in primary effluents, secondary effluents, and discharges, relative to raw sewage, was calculated. These calculations indicate that the best removal occurs for Pb, followed by Zn, Fe, Cr, Cd, Cu, P, Ag, Ni, Mn, and Co.

Filtration as a Barrier to Passage of Cysts in Drinking Water

Numerous outbreaks of waterborne giardiasis have occurred in the United States since 1973. Generally, the causes have been inadequate disinfection or inadequate filtration (perhaps none), or sometimes both. Even though research on water filtration for Giardia cyst removal is expected to continue in the future, sufficient information on water filtration for cyst removal is available now to provide some guidance for engineers who design filtration plants and for operators who run them.

Organic carbon removal by advanced waste water treatment processes

Fourteen physical-chemical processes singularly or in combination were evaluated for their ability to remove dissolved organic carbon in the effluent of a waste water reclamation facility treating secondary effluent. The largest organic carbon removals were obtained with reverse osmosis (RO) at an 85% product water recovery. As RO removals before and after activated carbon treatment were similar, RO may be employed directly following coagulation.

Heavy metal variability of different municipal sludges as measured by atomic absorption and inductively coupled plasma emission spectroscopy

Abstract Six sludge streams at two sewage treatment plants were monitored for three months to determine variability, degree of magnification, and generation rates of heavy metals and nutrients. Measurements of As, Ba, B, Cd, Cr, Cu, Pb, Hg, Mo, Ni, Se, Ag, Zn, K, N, P, ammonia, total solids, and volatile solids showed that most variability was related to the type of sludge (primary sludge, waste activated sludge, digested sludge, dewatered sludge), and to a lesser extent, to the day‐to‐day changes of a particular sludge stream.

Water‐soluble constituents of mount St. Helens ash

Abstract The elemental composition of Mount St. Helens ash samples and the amount of water‐leachable trace elements from the ash samples have been measured by inductively coupled plasma emission spectrometry and atomic absorption spectrometry. The leachable fraction of metals ranges from zero to 12 percent. It is speculated that the metals present in the leachates are mainly in colloidal form.

Concentration and biotoxicity assay of dilute aqueous solutions of volatile chlorinated organics using supercritical fluid extraction

Abstract Chlorinated volatile organic compounds (VOCs) were extracted from dilute aqueous samples into methanol to provide sufficient concentration for bacterial toxicity measurements. Using equipment designed to prevent loss of volatiles, standards and biological reactor effluents were filtered, adsorbed onto XAD‐2 resin, extracted using supercritical carbon dioxide, and cryotrapped in liquid nitrogen with methanol as a keeper solvent for toxicity measurements using the Microtox bioassay system. The levels of 15 VOCs were increased 7–36 times in the methanol concentrates over the aqueous concentrations which ranged from 5 to 100 μg/L. Mass recoveries averaged 76%. Using this system, the effluent of an anaerobic bioreactor treating a complex mixture of chlorinated organics was found to be significantly less toxic than the influent (46% less), but the toxicity of the total organic halide fraction increased by 80%.