Health survey of residents living near farm fields permitted to receive biosolids

Influence of seasonal fluctuation and loading rates on microbial and chemical indicators during semi-continuous anaerobic digestion

Minimal attention is paid towards the performance of the 40 million small-scale digesters which frequently operate at psychrophilic temperatures. Understanding the levels of microbial and chemical indicators at various loading rates and temperatures is useful for improving treatment efficiency and management strategies for small-scale digesters. In this study, semi-continuous anaerobic digesters were operated in replicate at four different loading rates (control, 0.3, 0.8 and 1.3 kg VS/m(3)/day) and housed in an environment that simulated seasonal change (27.5°C,10°C and 27.5°C). The results illustrate that class B quality biosolids were generated for all treatments as per guidelines from the United States Environmental Protection Agency (USEPA). The simulated seasonal change did not influence Escherichia coli or faecal coliform levels, while it did appear to have an effect upon levels of Enterococci. Reduced loading rates led to a more stable environment (in terms of pH, levels of volatile fatty acids (VFAs) and total inorganic carbonate (TIC)) as well as lower levels of indicator bacteria, but generated slightly lower biogas volumes (high--53.23 L vs. low--53.19 L) over the course of the study. The results provide important data to improve the performance of small-scale psychrophilic digesters, specifically by reducing loading rates to prevent souring during winter months.

Odors from sewage sludge and livestock: associations with self-reported health

OBJECTIVES

Class B treated sewage sludge (TSS) contains microbes and toxicants and is applied to land in areas where livestock wastes may be present. We evaluated relationships of reports of TSS and livestock odors with acute symptoms and excessive flies.

METHODS

A total of 158 adults living near liquid TSS application sites, 85 living near cake TSS application sites, and 188 living in comparison areas responded to a household survey regarding odors, health, and demographics. We identified symptom groups using factor analysis. We used generalized estimating equations to fit linear models for associations between factor scores and odors, and Poisson models for associations with specific symptoms.

RESULTS

Most factor scores were similar between exposure groups. Covariate-adjusted z-scores for lower respiratory symptoms were 0.28 (95% confidence interval [CI] -0.10, 0.65) higher among residents who reported moderate to very strong liquid TSS odor than among residents in comparison areas, and 0.28 (95% CI 0.05, 0.50) higher among residents who reported moderate to very strong livestock odor compared with residents reporting no or faint livestock odor. The factor score for dermatologic conditions was higher among residents who reported higher liquid sludge odor (0.27, 95% CI -0.13, 0.68), primarily due to skin rash (prevalence ratio = 2.21, 95% CI 1.13, 4.32). Excessive flies were reported twice as commonly among respondents who reported moderate to very strong TSS odor than among other residents.

CONCLUSIONS

Reported odors from TSS and livestock were associated with some acute symptoms. Health departments should monitor land applications of human and animal wastes and conduct surveillance of health problems reported by neighbors.

Public attitudes and risk perception toward land application of biosolids within the south-eastern United States

A descriptive-correlational study of biosolids recycling was conducted in the south-eastern United States to assess current knowledge, attitudes and risk perceptions of participants in two communities that land apply biosolids as part of their waste management programs. One community, Amelia County VA, has been outspoken against biosolids recycling in the past, whereas the second community, Knoxville, TN region, has voiced few concerns about biosolids recycling. Additionally, gender differences within the entire study population were assessed. A 45-question telephone survey, utilizing a 4-point Likert scale, was developed and administered to 311 randomly selected adults in the two regions. Commonalities identified during the study revealed key risk perceptions by the public regarding biosolids regulations, treatment, and application. Given current perceptions and knowledge, respondents felt that the benefits derived from biosolids recycling do not offset the perceived health and safety risks. However, as distance between application and personal property increased, a decrease in opposition of biosolids reuse became evident for all respondents. Survey participants were dissatisfied with the level of stakeholder involvement in research and decision-making processes concerning biosolids. The outspoken Amelia County residents perceived greater health risks due to inadequate treatment of biosolids and odorous emissions during the application process than the less engaged Knox Metro respondents. Significant gender differences were observed with sampled females perceiving greater risks to health and safety from biosolids recycling than males. There was also indication that decisions and risks were not sufficiently communicated to the public, leading to respondents being inadequately informed about biosolids land application in both communities. Community-specific outreach programs must address these public risk perceptions and the differences in perception caused by gender and issue awareness to assist solid waste managers in developing and implementing successful biosolids land application systems that are acceptable to the public.

Toward a consensus view on the infectious risks associated with land application of sewage sludge

The science linking processed sewage sludge (biosolids) land application with human health has improved in the last ten years. The goal of this review is to develop a consensus view on the human health impacts associated with land-applying biosolids. Pre-existing risk studies are integrated with recent advances in biosolids pathogen exposure science and risk analysis. Other than accidental direct ingestion, the highest public risks of infection from land application are associated with airborne exposure. Multiple, independent risk assessments for enteroviruses similarly estimate the yearly probabilities of infection near 10(-4). However, the inclusion of other emerging pathogens, specifically norovirus, increases this yearly infectious risk by over 2 orders of magnitude. Quantitative microbial risk assessment for biosolids exposure more effectively operates as a tool for analyzing how exposure can be reduced rather than being used to assess "safety". Such analysis demonstrates that the tradition of monitoring pathogen quality by Salmonella spp. and enterovirus content underestimates the infectious risk to the public, and that a rigorous biosolids pathogen treatment process, rather than extending community separation distances, is the most efficient method for reducing pathogen exposure and infectious risk.

Pollution sources and mortality rates across rural-urban areas in the United States

PURPOSE

To conduct an assessment of rural environmental pollution sources and associated population mortality rates.

METHODS

The design is a secondary analysis of county-level data from the Environmental Protection Agency (EPA), Department of Agriculture, National Land Cover Dataset, Energy Information Administration, Centers for Disease Control and Prevention, the US Census, and others. We described the types of pollution sources present in metropolitan and nonmetropolitan counties and examined the associations between these sources and rates of all-cause, cardiovascular, respiratory, and cancer mortality while controlling for age, race, and other covariates.

FINDINGS

Rural counties had 65,055 EPA-monitored pollution discharge sites. As expected, rural counties had significantly greater exposure to potential agriculture-related pollution. Regression models specific to rural counties indicated that greater density of water pollution sources was significantly associated with greater total and cancer mortality. Rural air pollution sources were associated with greater cancer mortality rates. Rural coal mining areas had higher total, cancer, and respiratory disease mortality rates. Agricultural production was generally associated with lower mortality rates. Greater levels of human development were significantly related to higher adjusted total and cancer mortality.

CONCLUSIONS

The association between pollution sources and mortality risk is not a phenomenon limited to metropolitan areas. Results carry policy implications regarding the need for effective environmental standards and monitoring. Further research is needed to better understand the types and distributions of pollution in rural areas, and the health consequences that result.

Environmental impacts and sustainability of degraded water reuse

Greater urban demand for finite water resources to meet domestic, agricultural, industrial, and recreational needs; increased frequency of drought resulting from erratic weather; and continued degradation of available water resources from point and nonpoint sources of pollution have focused attention on the reuse of degraded waters as a potential water source. However, short- and long-term detrimental environmental impacts and sustainability of degraded water reuse are not well known or understood. These concerns led to the organization of the 2007 ASA-CSSA-SSSA Symposium entitled Environmental Impacts and Sustainability of Degraded Water Reuse. Out of this symposium came a special collection of 4 review papers and 12 technical research papers focusing on various issues associated with the reuse of agricultural drainage water, well water generated in the production of natural gas from coalbeds, municipal wastewater and biosolids, wastewater from confined animal operations, urban runoff, and food-processing wastewater. Overviews of the papers, gaps in knowledge, and future research directions are presented. The future prognosis of degraded water reuse is promising, provided close attention is paid to managing constituents that pose short- and long-term threats to the environment and the health of humankind.