Use Of Biosolids In Agriculture Research Articles

ChemInform Abstract: Emerging Organic Contaminants in Biosolids and Assessment of International Research Priorities for the Agricultural Use of Biosolids

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Leaching Behavior of Heavy Metals In Biosolids Amended Sandy Soils

Use of biosolids in agriculture to improve crop production and soil quality have created concerns due to content of heavy metals that may affect surface or ground water quality. A column leaching study was conducted to evaluate the leaching potential of copper (Cu), lead (Pb), zinc (Zn), cdmium (Cd), cobalt (Co), chromium (Cr), and nickel (Ni) from two typical agricultural sandy soils in South Florida (Spodosol and Alfisol) with increasing application of pelletized biosolids (called PB) at the rates of 0, 1.25, 5.0, 10.0 g kg−1, respectively together with chemical fertilizer (CF). Elevated PB rate resulted in reduced leaching loss of Cu, Pb, Zn, Cd, Co, Ni from Spodosol, but resulted in increased loss of Pb, Zn, Cd, and Co from Alfisol. Significant reduction in Cu loss occurred in both soils, which can be attributed to the strong binding of Cu with organic matter from the applied PB. Percentage of Cd loss as of total Cd was 13% – 41%, the highest in all the heavy metals, whereas loss of Pb as of total Pb was less than 6.6%, though the concentrations of Pb, Cd, Co, and Ni in leachate were mostly above the limits of U.S. EPA drinking water standards or the national secondary drinking water standards. These results indicate that soil properties, PB application rates, and chemical behavior of elements jointly influence the leachate total loads of heavy metals in sandy soils applied with biosolids. Application of CF together with BP at a rate higher than 10.0 g kg−1 for sandy soils may pose potential threats to water quality due to enhanced leachate loads of Cr and Ni in Spodosol and Pb, Zn, Cd, Co and Ni in Alfisol.

Quality Protocols for Biosolids – Securing the Future

ABSTRACT The government and the regulator in the UK have a program to develop a series of Quality Protocols (QP) whose purpose is to identify the point at which particular materials cease to be waste and therefore when waste regulation controls no longer apply. This paper will report on a UKWIR research project whose objectives are to: − establish criteria for biosolids to achieve ‘product’ status; − develop a QP for the use of biosolids in agriculture; − assess criteria for the use of biosolids used in land reclamation, co-composting and as a fuel. The aims of the QP for biosolids used in agriculture are to: − judge at what point the material can be considered as a product and not a waste and hence lighten the Waste Management Licensing Regulations (WMLR) administrative burden; − provide procedures which would provide assurance to the stakeholders that the requirements of the Safe Sludge Matrix and the Sludge (Use in Agriculture) Regulations were being adhered to; − provide a useful lobbying tool to influence the drafting of future EU Directives and UK Regulations. A modular approach to the QP based on the principles of Hazard Analysis Critical Control Point (HACCP) have been applied in order to accommodate the different types of sludge treatment and to control all the stages of the whole process from controlling potential contaminants at source through to land application. The benefits of gaining QP status are that the confidence of stakeholders will be assured by its independently audited rigor, the oversight by regulators can be lightened and those who apply good practice can differentiate themselves from those who do not. The Biosolids QP is a means of securing the future of land application.

The use of a national communication program to secure future biosolids outlets in Norway

Norway is among the leading countries in the world regarding the quantity and quality of treated sludge (biosolids) recycled to agriculture. However, for nearly 3 years ago the Norwegian Farmer's Union requested a scientific risk assessment of the use of biosolids for agricultural purposes. Considering the scepticism towards use of biosolids in agriculture in the neighbouring countries and possible impacts on domestic market mechanism, it cannot be taken for granted that agricultural outlets will continue to be the main recycling route in Norway in the future To meet these challenges the Norwegian Water and Wastewater Association (NORVAR) has developed a national communication program in order to enhance mutual confidence and information transfer between the major stakeholders. The main objective of the program is to promote public acceptance and confidence in the utilitarian value of recycled biosolids. The program was implemented in 2005 as a 3 year program period and comprises objectives, strategies and measures respectively. Experiences indicate that implementing the communication strategy will play an important role in securing biosolids recycling routes in Norway in the future. The paper will give a brief presentation of the program, experiences, results achieved, challenges and the way forward.

Características biológicas do solo indicadoras de qualidade após dois anos de aplicação de biossólido industrial e cultivo de milho

A utilização agrícola de biossólidos tem sido muito incentivada, mas, como esses resíduos apresentam composição química variada, o valor agronômico e os efeitos sobre características indicadoras de qualidade do solo precisam ser avaliados caso a caso, a fim de estabelecer normas de segurança para uso desses materiais. Neste trabalho foram avaliadas características biológicas, após a aplicação, por dois anos consecutivos, de doses crescentes (0, 6, 12, 18 e 24 t ha-1 base seca) de um biossólido gerado por uma indústria de fibras e resinas PET e da adubação mineral completa no cultivo de milho, em um Cambissolo distrófico, comparados aos de uma área adjacente, sob Brachiaria sp. e sem cultivo nos últimos 10 anos, usada como referência. Os valores de C e N da biomassa microbiana, a respiração basal e as atividades das enzimas urease e beta-glicosidase e da hidrólise do diacetato de fluoresceína (FDA) aumentaram, enquanto a atividade da fosfatase ácida diminuiu com a elevação das doses de biossólido, porém estas não tiveram efeito sobre o quociente metabólico (qCO2). A diminuição da atividade da fosfatase se deveu ao aumento da disponibilidade de P no solo, não caracterizando efeito adverso da aplicação do biossólido. Com aplicação de 12 t ha-1 de biossólido (recomendação agronômica), a respiração e a hidrólise da FDA foram maiores e a atividade da fosfatase foi menor que a obtida no solo com adubação mineral, mas as demais características avaliadas não diferiram entre estes tratamentos. A colonização micorrízica de Brachiaria sp. não diferiu entre plantas de crescimento espontâneo nas parcelas anteriormente cultivadas com milho e aquelas da área adjacente. Apesar do menor número de esporos, verificou-se enriquecimento de espécies de fungos micorrízicos arbusculares (FMAs) nas parcelas cultivadas. O carbono orgânico (Corg) e a biomassa microbiana apresentaram alta correlação com os demais parâmetros avaliados, indicando que as alterações na quantidade e qualidade da matéria orgânica, promovidas pela aplicação do biossólido, refletiram na dinâmica da microbiota e influenciaram positivamente os parâmetros biológicos de qualidade do solo.

Comparison between pine bark and coconut husk sorption capacity of metals and nitrate when mixed with sewage sludge

Waste products such as biosolids and wood wastes have been frequently used in container production of plants. The use of biosolids in agriculture is a beneficial mean of recycling the by-products of waste-water treatment. However, care must be taken to avoid environmental or human health problems via run-off and leaching. The objective of this work is to compare the retention capacity of cadmium, lead, zinc and nitrate between pine bark (PB) and coconut fibre (F) when mixed with increasing amounts of composted sewage sludge (CSS) (0%, 15% and 30% (v/v)). Substrates were packed into leaching columns and irrigated with deionised water every 2 days. Leachates were collected during 1 month, and nitrate, Zn, Cd, Pb, EC and pH were monitored along the experiment. PB columns leached lower amount of nitrate than the coconut fibre ones. The same trend was observed for Zn, Cd and Pb. It could be said, that in order to minimize the environmental risks of using sewage sludges our results indicate that it is preferred to mix the sludge with pine bark instead than with coconut husk.

Fate of organotins in sewage sludge during anaerobic digestion

Adsorption onto sewage sludge is an important process for the elimination of tributyltin (TBT) from wastewater. However as the disposal of sewage sludge to agricultural land is a significant route for recycling biosolids, there exists an issue as to whether the potential long-term build-up of organotins in agricultural soil is acceptable, from a human health and environmental point of view. For the sustainable use of biosolids in agriculture it is essential to control and reduce the quantities of persistent pollutants such as organotins in sewage sludge. In this study, a sampling program was designed to establish the levels of TBT (and other organotins) in sewage sludge and their reduction during anaerobic treatment and processing prior to disposal. Experiments were also undertaken to assess the fate of TBT in laboratory scale anaerobic digesters where the influence of digester operating parameters could be evaluated. Organotin concentrations were determined using capillary gas chromatography with flame photometric detection. The results demonstrated that the majority of TBT remained concentrated in the solid phase (sewage sludge). Concentrations of TBT in sewage sludge were approximately 18 mg kg(-1) (dry weight) and both laboratory experiments and fieldwork demonstrated that degradation of TBT during anaerobic digestion of sludge was minimal.

Association between intestinal parasitic infections and type of sanitation system in rural El Salvador

To identify demographic, behavioural and environmental determinants of intestinal parasitic infection, evaluate the impact of a variety of dry sanitation systems on intestinal parasitic infection, and evaluate the safety of using stored biosolids in agriculture in order to guide future sanitation interventions in rural areas of El Salvador. Interviews were conducted with 109 households in eight communities where double-vaulted and solar urine-diverting desiccating latrines, pit latrines or no latrines were used. Faecal samples from 499 individuals were tested for enteric helminths and protozoa. Users of solar desiccating latrines had the lowest prevalence of enteric parasite infection. Double-vault, urine-diverting desiccating latrines effectively reduced the transmission of some pathogens, but may not achieve the conditions sufficient for the complete destruction of the more environmentally persistent pathogens, Ascaris lumbricoides and Trichuris trichiura. Contact with inadequately treated latrine biosolids was associated with an increased risk of Ascaris infection. Solar latrines were associated with the overall lowest prevalence of enteric parasitic infections. Members of households where latrine biosolids were used in agriculture had a higher prevalence of infection than those where biosolids were buried. We therefore recommend the promotion of solar latrines in rural areas of El Salvador over other dry sanitation systems, and recommend that stored biosolids not be used in agriculture.

Biosolids recycling: Nitrogen management and soil ecology

Biosolids are municipal wastewater treatment solids that meet regulatory standards for land application. Most biosolids are a rich source of N, P, and micronutrients. Although the use of biosolids on food crops remains controversial in the public eye, decades of research have led to the development of regulations for the safe and beneficial use of biosolids in agriculture. Emerging areas of research include biosolids in commercial and home horticulture, the fate of pathogens and organics in biosolids, the use of biosolids in the remediation of contaminated sites, and biosolids effects on soil ecology. Nutrient management remains the most critical day-to-day issue for land application of biosolids. Recent research on plant-available nitrogen (PAN) in biosolids has found that N availability is similar over a range of biosolids processing types, and that growing-season climate is a key factor affecting available N. Regionally based predictions of PAN have been developed for the United States, and could be extended into Canada. Relatively little is known about the effects of biosolids applications on soil ecology, but soil nematodes offer an opportunity to evaluate the structure and function of the soil ecosystem following biosolids applications. We have studied responses of nematode communities to application of municipal biosolids and composts, in forage production systems and orchards. Both types of amendments increased the abundance of enrichment opportunists, for up to 3 yr after single applications. These data on the persistence of increased enrichment opportunists have provided insight into the longevity of amendment-induced enhancement of biological activity and nutrient cycling. Cumulative biosolids applications of 90 Mg ha-1 have caused reductions in abundance of pollutant-sensitive Dorylaimida. The extent to which this change is the result of metal or nutrient loading is unclear and deserves more detailed study. Key words: Biosolids, plant-available nitrogen, soil ecology, nematodes

Recycling biosolids to pasture-based animal production systems in Australia: a review of evidence on the control of potentially toxic metals and persistent organic compounds recycled to agricultural land

Biosolids from municipal waste water treatment are commonly used in agriculture as a source of nutrients, organic matter, and irrigation. There is, however, concern that the use of biosolids on pasture can lead to an accumulation of potentially toxic metals (PTM) and persistent organic compounds (POC) in the surface layers of soil and associated herbage that can be ingested by grazing livestock. This review examines the following two key questions. Is the use of these materials in an agricultural setting safe and practical? Is the use of biosolids safe in all climates, on all soils, and is it sustainable over the long term? To answer these important questions, the Australian regulatory framework is examined in light of similar legislation in Europe and the United States on the basis of scientific evidence that underpins the published limits, contaminant gradings, annual loadings, and prescribed restrictions on the use of biosolids in agriculture. The review concludes that the regulatory frameworks currently enacted at State level suffer from a lack of data to underpin the risk assessments conducted to prevent transfer of PTM and POC to the human food chain from livestock production and the basis of published thresholds is poorly defined. The important areas of future research are identified as studies on acquisition and transfer of PTM and POC to grazing animals and the subsequent effect of attenuation of the pollutant on the human food chain, the validation and acceptance of methods to quantify POC in biosolids, the effect of recycling of biosolids on the economic performance of pasture-based agriculture, and the market perception of animal products produced from land receiving biosolids.