Potential for parasitic disease transmission with land application of sewage plant effluents and sludges

Land application of sewage plant effluents and sludges is being considered by planners because of environmental problems arising from alternative approaches and as a means of recovering the soil enrichment qualities of sewage effluents and sludges. A review of the literature shows that primary and secondary treatment, anaerobic sludge digestion, and routine disinfection (chlorine or ozone) do not destroy completely parasitic forms. Because of their weight most cysts and eggs are found in the sludge. Sludge digestion does destroy protozoan cysts but not all metazoan eggs. These cysts and eggs are extremely resistant in field conditions and some can persist infective for long periods. Documented disease transmission to humans from land application programs is related only to use of raw, not treated, sewage on land. Some animal disease transmission has been found related to untreated and partially treated sewage. Those who have examined sewage plant effluents and sludges for parasitic cysts and eggs have found them present. The most commonly reported species are: E. histolytica, Ascaris lumbricoides, Trichuris trichiura, Hymenolepis spp, Taenia sp. Enteroblus vermicularis, Ancylostoma and Necator. Destruction of all pathogenic forms can be assured by adequate heating of material to pasteurization temperatures of 60°C or more for 30+ min. Direct heating or composting can accomplish this. Parasitic disease transmission can be reduced by controlling the types of land to which these sewage plant products are applied. Parasitic disease transmission should be considered in developing the technology and/or management approaches to land application of sewage plant products for soil enrichment purposes.     

Data management for land disposal of liquid sludge

Metrogro is a program for augmenting the soil on privately-owned farms by application of liquid digested sludge. The system has been operated since 1979. In 1982, more than 60 farmers had approx. 2900 acres of crop land treated. The success of the program has been due to the active marketing and service program as well as to financial savings to farmers who may save more than $60 per acre in fertilizer costs. A comprehensive program to monitor the soil, crop, sludge, and groundwater provides large amounts of information. The data base now includes data on the physical and chemical properties of the sludge, soil chemistry, amounts of sludge hauled and applied, and information on more than three hundred wells in the region. These data are organized into seven computer files which can be queried and manipulated using a data management program.     

The effect of sewage sludge land disposal on the microbiological quality of groundwater

The long term effect of farmland disposal of anaerobically digested sewage sludges (alum, iron and lime) on the microbiological quality of groundwater was investigated using the lysimeter system. It was observed that after 4 years of heavy sludge application (5100 kg TKN ha⁻¹ 4 yr⁻¹), 92–98% of the sewage micoorganisms in the sludge had perished in the soils systems. Analyses of leachates and soils for coliforms and heterotrophic bacterial populations revealed that there was little possibility of microbiological contamination of groundwater by the practice of sludge farmland disposal, provided that the groundwater table was not too high and the soil was well-drained.     

P3E/C在大连LNG陆域形成地基处理中的应用

介绍了P3E/C软件的主要功能特点,结合大连LNG陆域形成地基处理工程实例,阐述了P3E/C软件在地基处理工程中的应用,对其应用成效进行了分析,指出应用P3E/C软件作为项目管理软件,提高了项目管理水平及工作效率,确保了大连LNG项目按期完工.     

Measurement of glutathione in activated sludges

Thermal, electric, mechanical or oxidative stress seem a promising way to reduce the production of excess activated sludge during biological wastewater treatment. However, the adaptation and the resistance of the sludge microbial ecosystem to stress conditions is a major question as it may definitively limit the effect of some treatments. Defence mechanisms developed by aerobic organisms, in particular, in response to oxidative stress involve various antioxidant activities and compounds such as glutathione. An HPLC method was developed for measuring reduced and total glutathione (GSH and GSHt) in perchloric acid sludge extracts. The method was sensitive, highly specific and validated for linearity, precision and recovery. Considering the extraction yield and the oxidation of GSH during extract storage, the measured GSH concentration was estimated to represent 60% of the GSH content from activated sludges. GSHt ranged from 0.32 to 3.34micromolg(-1) volatile solids and the GSH/GSHt ratio ranged from 32% to 91%. Measurements performed on sludges stressed in precise conditions selected to reach a reduction of sludge production showed a decrease of GSH and GSHt concentrations with thermal, mechanical, electric and ozone stress.     

Development of a soil—waste interaction matrix for assessing land disposal of industrial wastes

Environmental impact assessment of industrial solid or liquid waste disposal on land is characterized by a soil—waste interaction matrix. Procedures are developed for the ranking of industrial liquid wastes and potential disposal sites. Wastes are described by parameters arranged into an effects group (human toxicity, groundwater toxicity, disease transmission potential), a behavioural performance subgroup (chemical and biological persistence, and sorption), a behavioural properties subgroup (viscosity, solubility, acidity/basicity), and a capacity-rate group (waste application rate). Soil-sites are described by parameters arranged into a soil-group (permeability, sorption), a hydrology group (water table gradient, infiltration) and a site group (distance to a point of use and thickness of the porous layer). A matrix format is used to combine waste parameter point scores (rows) with soil-site parameter point scores (columns), enabling the interactions to be quantified and related to acceptability levels. The matrix is intended for use by regulatory agencies as a tool in determining site suitability for the disposal of industrial wastes.     

Organic matter in degraded agricultural soils amended with composted and thermally-dried sewage sludges

The cumulative and residual effects of composted and thermally-dried sewage sludge (CSS and TSS, respectively) on soil organic matter and its humified fraction were evaluated in a field experiment under Mediterranean conditions. The experimental design included soil plots either unamended (control) or amended with mineral fertilizer, CSS and TSS at rates of 20 and 80 t ha(-)(1). After the first year of sewage sludge application, each plot was divided into two subplots. In one subplot group, no additional application of SS was made in the following 3 years, and the residual effect of the first applications was evaluated. In the second subplot group, the cumulative effect of sludge amendments was evaluated by applying CSS and TSS also in the following three consecutive years. Nine months after the yearly sludge and mineral fertilizer applications, surface soil samples from control and amended soils were collected and analyzed for total organic C (TOC), total extractable C (TEC), and humified C fractions, both humic acid C (HAC) and fulvic acid C (FAC) fractions. Compared with the control and mineral treatments, which showed similar results, the repeated application to soil of TSS, and specially CSS, induced an increase on the content of the organic fractions examined, as well as HA percentage (%HA=HAC/TOC) and degree of polymerisation (DP=HAC/FAC). In the residual experiment, the TOC, TEC, HAC and FAC content of soils amended once with CSS and TSS decreased slightly when increasing the time from the amendment, whereas the %HA and DP tended to increase. Further, three years after the sludge applications, with respect to the control soil, the soils amended once with CSS exhibited similar TOC, TEC, and FAC content, and slightly larger HAC content, %HA and DP; whereas those amended once with TSS, featured still larger TOC, TEC, HAC content, similar FAC content, and slightly larger %HA and DP values. As a whole, the results obtained suggested that both kind of sludges contribute to improved soil organic matter levels and humified fractions, although the CSS contribution can be considered as a more efficient organic amendment than the TSS, which may present problems of maturity and degradability.     

Physico-chemical characteristics of full scale sewage sludges with implications to dewatering

An investigation was carried out for a variety of different sewage sludges in order to establish correlations between sludge composition, structure and dewatering properties. Results indicated that the fraction of extracellular polymeric substances (EPS) in sludges was the most important parameter with respect to sludge structure. With high EPS contents, sludges had a lower shear sensitivity and lower degree of dispersion. This in turn lead to better filterability in terms of low resistance to filtration (SRF). The floc stabilising role of EPS components was not consistent with DLVO-theory, as the zeta-potential increased with increased EPS content due to increased EPS charge content. This indicates that polymer entanglement is a key factor to stable floc structure. This does not rule out the possible change in dispersion due to changed electrostatic repulsion for a given EPS content. While EPS had a good effect on floc stability and filterability, the cake dry matter content decreased with large EPS contents. This could be due to an osmotic pressure related to the polymer charge quantity, or it could be caused by water entrapment in the floc structures. A high degree of sludge dispersion increased the cake dry matter content in filtration. This mechanism is, however, impractical due to high SRF and not important to conditioned sludge. In practice, dewatering also includes sludge expression. Taking this into account, osmosis related to EPS charges is likely to be increasingly important (increasing the negative effect of EPS content on cake dry matter).     

Occurrence of synthetic musks in Korean sewage sludges

Six polycyclic musks (PCMs) and five nitro musks (NMs) were analyzed in dewatered sludge samples from 13 municipal, 4 livestock and 1 pharmaceutical wastewater treatment plants (WWTPs) in South Korea. 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB; Galaxolide^®, Abbalide^®), and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN; Tonalide^®, Fixolide^®) were the two predominant PCMs in the sludge samples, at concentrations ranging from 0.52 to 82.0 mg/kg dry weight (dw) and 0.12 to 28.8 mg/kg (dw), respectively, suggesting the extensive use of these two PCMs in South Korea. Hierarchical cluster analysis (HCA) revealed the different usage patterns of PCMs between livestock cultivating farm and household. The levels of HHCB and AHTN in the effluent discharged from the WWTPs were lower than the threshold effect levels derived for fish, suggesting low potential risks to aquatic organisms. Nevertheless, the calculated discharge of synthetic musks (SMs) from sludge in each target WWTP ranged from 36 to 10,961 g/d. These results indicate the necessity of conducting monitoring studies in marine ecosystems due to ocean disposal of sludge, particularly focused on the two prevailing PCMs.     

城市污水厂污泥处置技术分析及福州市污泥处置的思考

本文对城市污水厂污泥处理处置主要技术进行分析,并阐述了国外污泥处置技术发展趋势,提出了污泥处理处置工作急需解决的问题。结合当前的污泥处置技术发展趋势,通过对福州市污水厂污泥处置现状及存在问题分析,提出了福州市今后的污泥处置技术路线:将厌氧消化做为有效减容、减量的手段,对污染物指标达到国家土地利用标准的污泥考虑土地利用,污染物指标不符合国家土地利用标准的污泥考虑焚烧和建材利用。     

Organic markers in the lipidic fraction of sewage sludges

The lipidic organic fraction of 48 sewage sludges that originated from food-processing, paper-mill and domestic (urban, small urban, and rural) wastewater-treatment plants of the Lorraine region (Northeast of France) was characterised by gas chromatography coupled with mass spectrometer (GC-MS). This study enables us to define an average organic composition typical of each group of sewage sludges. Linear alkyl benzenes (LABs) are only present in domestic sludges, sterols in food-processing and domestic sludges. Paper-mill sludges are characterised by the specific distribution of n-alkanes. Besides, all the domestic sludges, whatever the size of the wastewater catchment, are characterised by the same distribution of polar compounds. Differences can be evidenced in the distribution of the aliphatic compounds of some domestic sewage sludges and are attributed to the important contribution of petroleum products in their sewer system. Moreover, this study highlights the correlation between abundance of polycyclic aromatic hydrocarbons (PAHs) in the aromatic fraction of some sewage sludges and a distribution of n-alkanes characteristic of heavy petroleum products into the corresponding aliphatic fraction. This might be a clue for the determination of punctual sources of PAHs.     

Evaluation of the extracellular proteins in full-scale activated sludges

The proteins present in the extracellular polymeric substances (EPS) of activated sludge flocs were investigated using three cation-associated extraction methods. The subproteomes generated from four full-scale activated sludges were subsequently fractionated by ammonium sulfate precipitation and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that each extraction method led to unique SDS-PAGE protein profiles, which provided strong evidence that the extracted proteins are uniquely associated with specific cations in activated sludge flocs. The comparison of protein profiles across sludges from different treatment plants revealed that extracts obtained using a cation-exchange resin exhibited similar protein banding patterns while sulfide- and base-extracted EPS led to more variable protein profiles. Analysis of several SDS-PAGE bands by liquid chromatography-tandem mass spectrometry of tryptic digests led to the identification of several bacterial proteins as well as sewage-derived polypeptides (human elastase IIIA and keratins). Their putative roles in activated sludges and their association with targeted cations are proposed.     

Purification and characterization of extracellular polysaccharide from activated sludges

A three stage purification process has been developed for soluble, activated-sludge exocellular polymers which results in a polysaccharide fraction substantially free of nucleic acids and protein, with the residual protein probably bound as a glycoprotein. Characterization and comparison of purified exopolysaccharide fractions from five different effluent treatment works revealed many similarities both in terms of monomer composition and molecular weight distribution. Only five monomers were detected, namely: glucose, galactose, mannose, glucuronic acid and galacturonic acid, and all the polysaccharide fractions were of high molecular weight, ranging from 3 × 10⁵ to 2 × 10⁶.     

Alkylamine odors from degradation of flocculant polymers in sludges

The cationic organic polymers used to enhance thickening and dewatering processes are potential sources of strong odors. These polymers vary in chemical structure, and some may be more susceptible to biotic or abiotic degradation than others. The product organic amines will be volatilized most noticeably at high pH, as in lime addition. These possibilities were examined using several structural types of polymers combined with anaerobically digested sludge. Two commonly used polymers gave significant production of trimethylamine (TMA), which was released upon lime addition. Their structures were correlated with reactions that yield TMA. An initial ester hydrolysis step appears to be biologically mediated, but subsequent steps can occur due to alkaline conditions. An alternative cationic polymer structure did not generate TMA but required a much higher dose to effect sufficient conditioning of the sludge. The acrylamide-based polymers were shown to be the predominant source of TMA in limed sludges.     

Anoxic oxidation of arsenite linked to denitrification in sludges and sediments

In this study, denitrification linked to the oxidation of arsenite (As(III)) to arsenate (As(V)) was shown to be a widespread microbial activity in anaerobic sludge and sediment samples that were not previously exposed to arsenic contamination. When incubated with 0.5 mM As(III) and 10 mM NO₃⁻, the anoxic oxidation of As(III) commenced within a few days, achieving specific activities of up to 1.24 mmol As(V) formed g⁻¹ volatile suspended solids d⁻¹ due to growth (doubling times of 0.74-1.4 d). The anoxic oxidation of As(III) was partially to completely inhibited by 1.5 and 5 mM As(III), respectively. Inhibition was minimized by adding As(III) adsorbed onto activated aluminum (AA). The oxidation of As(III) was shown to be linked to the complete denitrification of NO₃⁻ to N₂ by demonstrating a significantly enhanced production of N₂ beyond the background endogenous production as a result of adding As(III)-AA to the cultures. The N₂ production corresponded closely the expected stoichiometry of the reaction, 2.5 mol As(III) mol⁻¹ N₂-N. The oxidation of As(III) linked to the use of common-occurring nitrate as an electron acceptor may be an important missing link in the biogeochemical cycling of arsenic.     

The anti-apartment movement in the U.S. and the role of land use regulations in creating housing segregation

In the U.S., typically, poor and minority households are concentrated in central cities, which are ringed by middle class suburbs which contain a majority of the population of the metropolitan area. The resulting segregation is largely the outcome of public policy and institutional arrangements, rather than the excesses of a free market. Land use regulations have played a central role in creating segregation among the types of housing that are affordable to different income groups. Single family only zoning is a central institution in suburban areas; often multifamily housing is limited to a very tiny portion of the land zoned for housing. Land use policies regarding housing are formulated on a municipal level, in which states have only a minimal role and the federal government has no role. Decentralization of revenue sources and fiscal support for local services, including education, provides incentives for local zoning policies which exclude groups which are viewed as more costly to service, while decentralization of zoning powers make these policies possible. This article describes 1) the basic contours of the housing stock and population distribution in metropolitan areas, 2) the evolution of the single family only policy, and 3) recent efforts to counteract housing segregation patterns, which have had little success. Kenneth K. Baar is a attorney in the Berkeley, California and has a Ph.D. in urban planning. From 1991 to 1993, he was a Fulbright professor at the Budapest University of Economic Sciences. In 1994–95 he was visiting professor in the Urban Planning Department at Columbia University in New York City.     

Accumulation of reserve polysaccharide in activated sludges treating carbohydrate wastes

Activated sludge from the actual plants was used to treat industrial wastes rich in carbohydrate, in order to determine the capacity of sludge to accumulate polysaccharide and the role of such accumulation in the removal of carbohydrate from the wastes.The capacity to accumulate reserve polysaccharide was relatively high for sludges treating wastes with a high ratio of carbohydrate BOD to toal BOD, such as confectionery, fruit juice and soft drink wastes. With wastes having a relatively low percentage of carbohydrate BOD, such as kraft pulp, yeast culture and brewery wastes, the capacity to accumulate reserve polysaccharide was lower than that of the former sludges, even though the wastes contained a relatively large amount of carbohydrate. The sludges with the high capacity to accumulate polysaccharide also showed a high initial rate of glucose removal, although a definite realtionship was not observed between the activity of the sludges to remove glucose and the respiratory activity with glucose.