Use Of Biosolids In Agriculture Research Articles

Terrestrial bioassays for assessing the biochemical and toxicological impact of biosolids application derived from wastewater treatment plants

Wastewater treatment plants (WWTP) are facilities where municipal wastewater undergoes treatment so that its organic load and its pathogenic potential are minimized. Sewage sludge is a by-product of this process and when properly treated is preferentially called “biosolids”. These treatments may include some or most of the following: thickening, dewatering, drying, digestion, composting, liming. Nowadays it is almost impossible to landfill biosolids, which however can well be used as crop fertilizers. Continuous or superfluous biosolids fertilization may negatively affect non-target organisms such as soil macro-organisms or even plants. These effects can be depicted through bioassays on terrestrial animals and plants. It has been shown that earthworms have been affected to various degrees on the following endpoints: pollutants' bioaccumulation, viability, reproduction, avoidance behavior, burrowing behavior. Collembola have been affected on viability, reproduction, avoidance behavior. Other terrestrial organisms such as nematodes and diplopods have also shown adverse health effects. Phytotoxicity have been caused by some biosolids regimes as measured through the following endpoints: seed germination, root length, shoot length, shoot biomass, root biomass, chlorophyll content, antioxidant enzyme activity. Very limited statistical correlations between pollutant concentrations and toxicity endpoints have been established such as between juvenile mortality (earthworms) and As or Ba concentration in the biosolids, between juvenile mortality (collembola) and Cd or S concentration in the biosolids, or between phytotoxicity and some extractable metals in leachates or aquatic extracts from the biosolids; more correlations between physicochemical characteristics and toxicity endpoints have been found such as between phytotoxicity and ammonium N in biosolids or their liquid extracts, or between phytotoxicity and salinity. An inverse correlation between earthworm/collembola mortality and stable organic matter has also been found. Basing the appropriateness of biosolids only on chemical analyses for pollutants is not cost-effective. To enable risk characterization and subsequent risk mitigation it is important to apply a battery of bioassays on soil macro-organisms and on plants, utilizing a combination of endpoints and established protocols. Through combined analytical quantification and toxicity testing, safe use of biosolids in agriculture can be achieved.

Knowledge, Attitudes, and Intentions of Biosolids use in Agriculture: Perspective from the Agricultural Managers of the Dominican Republic

Biosolids have benefits for soil and crop production and contribute to sustainable development. The use of biosolids in agriculture holds great potential for enhancing the economic development of rural communities. This research aims to analyze the mediating role of attitudes between knowledge and the intention to use biosolids as fertilizer. During the examination process 635 questionnaires were obtained, and statistical analysis was performed using Smart-PLS. The results of the study indicate that attitudes play a mediating role between knowledge and the intention to use biosolids in agriculture. In conclusion, it is emphasized in the need for positive attitudes towards the use of biosolids among agricultural managers, directors, technicians, and farmers. These results benefit the Dominican Republic's Ministry of Agriculture, agricultural professionals, and farmers. The Ministry can shape policies and offer education on biosolid use. Agricultural leaders should consider attitudes alongside knowledge.Farmers should stay informed and adopt biosolid practices for better crop productivity and soil health.

EFECTO DEL ABONADO CON BIOSÓLIDO EN EL COMPORTAMIENTO FISIOLÓGICO E INCIDENCIA DE PLAGAS EN CULTIVO DE CHILE X´CATIK (Capsicum annuum L.)

<p><strong>Background.</strong> The use of biosolids in agriculture allows to supply essential nutrients for the plant development. <strong>Objective</strong>. To evaluate the effect of supplying swine biosolids on the physio-agronomic characteristics and incidence of pests in X'catik pepper. <strong>Methodology.</strong> The experiment was carried out under greenhouse conditions and set in a randomized block experimental design with four replicates. Three different levels of biosolids were evaluated (500, 750 and 1000 g plant<sup>-1</sup>) and the control (no supply of biosolid). <strong>Results.</strong> Plants treated with 750 g de biosólido had the highest net carbon assimilation rate (A<sub>N</sub>) and the lowest intracellular carbon (Ci), likewise, there was a trend of higher values for the yield components in this treatment. The population density of <em>B. tabaci</em> and the damage by <em>Poliphagotarsonemus latus</em> was similar among treatments. <strong>Implications.</strong> The use of swine biosolid in agriculture represent a feasible alternative to enhance the plant physiological condition and potentially the yield in horticultural crops. <strong>Conclusion</strong>. The supply of 750 g plant<sup>-1</sup> of swine biosolid improved the physiological parameters in the X'catik pepper plants, had no effect on pest damage, but showed a strong tendency to increase yield.</p>

Identification and Evaluation of Determining Factors and Actors in the Management and Use of Biosolids through Prospective Analysis (MicMac and Mactor) and Social Networks

The reuse of biosolids in agriculture and its inclusion within the circular economy model requires evaluating and analyzing factors that intervene in its management. The objective of the study was to analyze those factors that influence the management and use of biosolids. Fifty-three actors were questioned, and their answers were analyzed using two prospective methods and Social Network Analysis (SNA) identifying between 14 and 19 variables. Six should be prioritized due to their criticality and potential in management and reuse scenarios. It was observed that the formulation of objectives, such as the improvement of infrastructure, creation of an institutional policy, and the establishment of definitions for the kinds of biosolids, are opposed by internal agents. Seven key actors and four to six determining agents were identified in the scenarios. The network of management and use of biosolids in agriculture presented low density (0.28) and the exclusive action of three key actors. Consequently, the participation of a greater number of better-connected actors is required to project networks with a higher density (between 0.49 and 0.57), facilitating the diffusion of information and the inclusion of new actors not previously contemplated. The application of prospective and SNA methodologies focused on biosolids allows the prioritization of determinants, the evaluation of the level of involvement and communication between actors, and other aspects that have not been considered previously in the management of WWTPs in Colombia.

Responses of the Soil Bacterial Community, Resistome, and Mobilome to a Decade of Annual Exposure to Macrolide Antibiotics.

Biosolids that are applied to agricultural soil as an organic fertilizer are frequently contaminated with pharmaceutical residues that have persisted during wastewater treatment and partitioned into the organic phase. Macrolide antibiotics, which serve as a critically important human medicine, have been detected within biosolids. To determine the impacts of macrolide antibiotics on soil bacteria, every year for a decade, a series of replicated field plots received an application of a mixture of erythromycin, clarithromycin, and azithromycin at a realistic (0.1 mg kg soil-1) or an unrealistically high (10 mg kg soil-1) dose or were left untreated. The effects of repeated antibiotic exposure on the soil bacterial community, resistome, mobilome, and integron gene cassette content were evaluated by 16S rRNA and integron gene cassette amplicon sequencing, as well as whole-metagenome sequencing. At the unrealistically high dose, the overall diversity of the resistome and mobilome was altered, as 21 clinically important antibiotic resistance genes predicted to encode resistance to 10 different antibiotic drug classes were increased and 20 mobile genetic element variants (tnpA, intI1, tnpAN, and IS91) were increased. In contrast, at the realistic dose, no effect was observed on the overall diversity of the soil bacterial community, resistome, mobilome, or integron gene cassette-carrying genes. Overall, these results suggest that macrolide antibiotics entrained into soil at concentrations anticipated with biosolid applications would not result in major changes to these endpoints. IMPORTANCE Biosolids, produced from the treatment of sewage sludge, are rich in plant nutrients and are a valuable alternative to inorganic fertilizer when applied to agricultural soil. However, the use of biosolids in agriculture, which are frequently contaminated with pharmaceuticals, such as macrolide antibiotics, may pose a risk to human health by selecting for antibiotic resistance genes that could be transferred to plant-based food destined for human consumption. The consequences of long-term, repeated macrolide antibiotic exposure on the diversity of the soil bacterial community, resistome, and mobilome were evaluated. At unrealistically high concentrations, macrolide antibiotics alter the overall diversity of the resistome and mobilome, enriching for antibiotic resistance genes and mobile genetic elements of concern to human health. However, at realistic antibiotic concentrations, no effect on these endpoints was observed, suggesting that current biosolids land management practices are unlikely to pose a risk to human health due to macrolide antibiotic contamination alone.

Part A: Sanitization and use of sewage sludge in soil Technical Note 6 - Agricultural use of biosolids

The biosolids resulting from the sludge treatment from sewage treatment plants improve soil conditioning and are rich in nutrients. However, despite the benefits to soil and plants, as well as the sustainable appeal, the agricultural use of biosolids in Brazil is still not widespread. In this Technical Note (TN), the objective is to present some Brazilian experiences with biosolids in the light of relevant legislation, as well as to discuss aspects and potential related uses. Paraná and São Paulo states are the main references in agricultural use, with experiences of sanitization with alkaline stabilization and composting. In this TN the criteria for the use of biosolids are presented, according to the new CONAMA Resolution 498/2020, as well as the challenges related to the agricultural sector and public acceptance. Public policies to support rural producers for the application of biosolids are also discussed, to promote transformation of a rich by-product of sewage treatment into a resource for agricultural use, in a vision of circular economy.

Part A: Sanitization and use of sewage sludge in soil Technical Note 4 - Sludge sanitization by alkaline stabilization

Alkaline stabilization (AS) is one of the most widespread processes in the world for the sanitization of sludge produced in sewage treatment, although in Brazil it is used by only a few sanitation companies. The fact that an environmentally sustainable destination for sewage sludge is not mandatory, as well as a series of economic, technical and operational factors, end up limiting the AS process application. The increase of AS practices are expected due to the the Brazilian CONAMA Resolution nº 498/2020, which aims to increase the use of biosolids in agriculture and to further deepen technical and operational knowledge related to this practice. This technical note (TN) presents the main forms of the storage and application of lime, as well as the minimum parameters required for designing maturation and curing yards. In this TN, the intrinsic AS costs and best engineering practices used are discussed, in view of reducing possible problems and maximizing its usage throughout the national territory.

Management Strategies and Stakeholders Analysis to Strengthen the Management and Use of Biosolids in a Colombian Municipality

The difficulties in the management and use of biosolids in Colombia make it necessary to evaluate and analyze the factors involved through various methodologies to achieve the effective management and recycling of this type of waste. The objective of this study was to evaluate the management of sludge and biosolids from a WWTP in a Colombian municipality through the application of three methodologies (SWOT/TOWS, surveys, and stakeholder (player) weighing) for their subsequent use in agriculture. As a result, strategies were proposed at the regulatory, organizational policy, and entity integration levels, among others. It was identified that about 93.6% of the people surveyed had a positive attitude towards the use of biosolids in agriculture, despite recognizing the existence of a risk (27.3%) in this type of practice. On the other hand, regarding the communication of WWTP management of these wastes, they perceived that it to be absent (65%) and the lack of knowledge regarding the destination of these wastes was even greater (72.7%). Through the weighting of actors, 16 players were classified with whom it is necessary to work closely, regularly, or occasionally. The methodologies proposed will allow similar WWTPs to optimize their processes through continuous improvement and joint work between the different entities and communities. It is recommended that other methodologies be used to evaluate player position level in relation to planned strategies, as well as the level of associations of one player with another, independent of power and influence.

Industrial Symbiosis through the Use of Biosolids as Fertilizer in Romanian Agriculture

Biosolids’ use in agriculture is an example of industrial symbiosis. The application of biosolids (BS) in agriculture is considered one of the most sustainable sewage sludge (SS) management options, but the quality of biosolids has to meet certain requirements regarding the characteristics of the sludge, those of the land and of the type of crop. Web of Science database has been used to search for the relevant literature. The review of studies undertaken in order to determine the economic effects of the use of biosolids in agriculture shows, in the majority, an increase in crop yield and the reduction in costs, due to the reduction in the requirements for the application of chemical or synthetic fertilizers. If the entire sewage sludge production in Romania for 2019 had been used as fertilizer, the estimated cost reduction for farmers would have been almost 3 million Euros—considering the 230.59 thousand tons of dry matter produced in 2019. The estimated savings for 2019 of the sewage and water utilities, if the sewage sludge had been used in agriculture instead of depositing it at the landfill, would have been about 3.9 million Euros. However, the limits of the symbiosis are due to the size of the farms, the type of plants cultivated, pH, slope inclination, heavy metal content and social acceptance. It is impossible to use all the sewage sludge in agriculture, but these figures are a good estimation of the economic effects.

Drugs in the environment: Do we know the risks?

Abstract The occurrence of residual drugs in sewage and natural waters is an important international topic. The behavior of compounds in the environment and sewage treatment plants (ETEs) is influenced by their physicochemical properties, which govern partition in water, soil or biota. The present study aims to identify the presence of clonazepan, simvastatin, paracetamol, atenolol, carbamazepine and fluoxetine drugs in biosolid from TEE before and after the composting process. Based on the Environmental Protection Agency's Structure-Activity Relationship Model (ECOSAR) Program (EPA), and according to ZAGATTO (2006), the octanol/water partition coefficient (Kow) observed for ibuprofen drugs, fluoxetine and sinvastanin was 3.97, 3.82 and 4.68, respectively, denoting its bioaccumulation potential, which does not happen with the other compounds, as they present logKow < 3, being log kow = 0.03 for atenolol; 2.3 for carbamazepine; 0.49 for paracetamol and 2.53 for clorazepam. AQUINO, 2013, mentions that drugs with logKow < 2.5 have high hydrophylycity and low absorption trend in biomass and lipid fractions of suspended solids. For Log Kow values between 2.5 and 4.0, there is a moderate tendency of absorption in these matrices. Data on ecotoxicity, provided by the ECOSAR program, indicate the effects observed in fish, at the concentration of 30 μg/L for Sinvastatin and 20 μg/L for Fluoxetine. The agricultural use of biosolids is a controversial subject due to the potential adverse impacts on human health. In the name of safety, strict standards, high quality criteria and restrictions on use are imposed, and standards should be based on risk assessment, but there is a lack of data on the subject, and there is still no clarity as to what constitutes tolerable risk in the brazilian context for the composition of a pattern. Key messages According to the results obtained, it is verified that the studied compounds have the potential to cause deleterious effects on the evaluated organisms, according to the ECOSAR model. Considering the little information available on the subject, especially in relation to the incidence and persistence of drugs in the environment, the continuity of studies is necessary.

Agricultural Use of Biosolids Generated in Wastewater Treatment of a Food Industry

Biosolids generated as waste from a Wastewater Treatment Plant (WTP) are a pollution problem by the provision of large volumes in landfills and the waste of their potential as an agricultural input. The research conducted trials to analyze the agricultural use of biosolids in a food company's WTP, their effects on the germination and development of the vegetal plant species Coriandrum sativum were assessed through trials that mixed different amounts of biosolids, land soil and commercial fertilizer, and took into account: planting site characteristics, biosolid and Coriandrum sativum. A random block design was made to compare treatments understudy and resulted in the combination of 50% biosolids with 50% land soil was the best test by germination, height, mass and length of the roots of the plant studied. In the evaluation of results, the behavior of dependent variables was analyzed: germination, height, mass and length with respect to the four test types with their respective repetitions using ANOVA and Fisher's significant minimum difference (LSD) to determine the effect the biosolid had on the plant and to know the optimal dose for its development. The germination rate (GR) was also determined in the trials, and 98.3% was found for the best treatment indicating that the substrate does not contain phytotoxic elements.

Occurrence of the Persistent Antimicrobial Triclosan in Microwave Pretreated and Anaerobically Digested Municipal Sludges under Various Process Conditions.

Treatment of emerging contaminants, such as antimicrobials, has become a priority topic for environmental protection. As a persistent, toxic, and bioaccumulative antimicrobial, the accumulation of triclosan (TCS) in wastewater sludge is creating a potential risk to human and ecosystem health via the agricultural use of biosolids. The impact of microwave (MW) pretreatment on TCS levels in municipal sludge is unknown. This study, for the first time, evaluated how MW pretreatment (80 and 160 °C) itself and together with anaerobic digestion (AD) under various sludge retention times (SRTs: 20, 12, and 6 days) and temperatures (35 and 55 °C) can affect the levels of TCS in municipal sludge. TCS and its potential transformation products were analyzed with ultra-high-performance liquid chromatography and tandem mass spectrometry. Significantly higher TCS concentrations were detected in sludge sampled from the plant in colder compared to those in warmer temperatures. MW temperature did not have a discernible impact on TCS reduction from undigested sludge. However, AD studies indicated that compared to controls (no pretreatment), MW irradiation could make TCS more amenable to biodegradation (up to 46%), especially at the elevated pretreatment and digester temperatures. At different SRTs studied, TCS levels in the thermophilic digesters were considerably lower than that of in the mesophilic digesters.

Ionic speciation and risks associated with agricultural use of industrial biosolid applied in Inceptisol.

The evaluation of the chemical leaching potential from soils amended with biosolid is of extreme importance for environmental safety of agricultural use of these residues. The objective of this study was to evaluate the polluting potential and possible risks associated with the agricultural use of biosolids generated by the polyethylene terephthalate (PET) fiber and resin industry through ionic speciation and analysis of the activity of chemical species present in the leached solution from Inceptisol treated with rates 0, 6, 12, 18, 24, 48, 96, and 144Mgha-1 on dry basis. The experiment was conducted in a lysimeter and the treatments with three replications were distributed at random. Chemical leaching was made by application of CaC12 0.01molL-1 solutions in a volume fourfold higher than the water retention capacity of the soil, divided into five leaching events: 210, 245, 280, 315, and 350days of incubation. Chemical species concentrations in collected leachates were used for ionic speciation by geochemical software Visual MINTEQA2 version 4.0. Impact factor of chemical species was calculated as the ratio between maximum concentration in the leach solution in the treated soil and control. Dissolved organic carbon had strong influence on Pb+2 and Cu+2 leaching, but these elements in free or complexed forms presented low activities in solution. Leaching of NO3-, Zn+2, and Na+ represents the main environmental risk of agricultural use of this residue. However, these risks can be minimized if technical criteria and critical limits for the agronomic use of biosolids were observed.

Environmental evaluation of the life cycle of elephant grass fertilization-Cenchrus purpureus (Schumach.) Morrone-using chemical fertilization and biosolids.

Law 12305/10, National Solid Waste Policy of Brazil, banned the disposal in landfills of any solid waste that could be converted to another use. Sludge produced at Industrial Wastewater Treatment Plants, which contains components characteristic of fertilizers, falls into this category. This type of sludge, also known as a biosolid, has great potential to replace commercial chemical fertilization. The use of biosolids in agriculture allows for compliance with new legislation, reducing the burden on landfills and reusing a waste product. The present paper utilizes the life cycle assessment methodology to compare the carbon footprint associated with the use of different quantities of biosolid and selected chemical fertilizers in the production of elephant grass. The IPCC 2013 GWP 100a method, which is based on data published by the Intergovernmental Panel on Climate Change, was selected as the environmental assessment method. The method expresses the emissions of greenhouse gases generated, in kilograms of CO2 equivalent, over a time horizon of 100years. The biosolid quantities used were based on the Brazilian Environment Council Resolution 375. The chemical fertilizer used contained urea, simple superphosphate, and potassium chloride. The use of biosolids in the amounts calculated according to Brazilian standards resulted in a carbon footprint approximately 17.7% lower than the use of the chemical fertilization mix, with similar productivity in both cases. The transportation of biosolids to the experimental area was responsible for the majority of emissions associated with the use of biosolids. Urea synthesis was the largest contributor to emissions resulting from the use of commercial chemical fertilizer, accounting for 73.6% of total emissions.

Bisphenol A in artificial soil: Effects on growth, reproduction and immunity in earthworms

The application of biosolids in agricultural fields is increasing annually. They contain not only nutrients but also xenobiotics, such as Bisphenol A (BPA). These compounds are not regulated in the use of biosolids in agriculture, which highlights the need to assess their effects on soil life, of which earthworms are most abundant of the animal representatives. In this study the effect of BPA on life-history parameters, such as mortality, growth and reproduction, and on immunity, is evaluated for Dendrobaena veneta and Eisenia fetida. Sublethal concentrations were evaluated by a modified OECD artificial soil test. Decline in growth with increasing concentration of BPA was detected during the first two weeks and the opposite effect for the next two, although these differences were only significant at the highest concentration. Reproduction traits were only significantly different for E. fetida, for which the number of juveniles decreased at higher concentrations, thus showing different sensitivity in both species. By using a contact test, the potentially harmful effect of direct contact with BPA was shown to be much higher than in soil (resembling natural) conditions. Finally, results indicate that BPA may not affect the immune system of these animals, at least in terms of coelomocyte viability.

Biosolid Application to Agricultural Land—a Contribution to Global Phosphorus Recycle: A Review

Phosphorus (P) is an essential nutrient required for plant development. Continuous population growth and rising global demand for food are expected to increase the demand for phosphate fertilizers. However, high–quality phosphate rock reserves are progressively becoming scarce. Part of the increased pressure on P resources could be alleviated by recycling P present in biosolids. Therefore, it is crucial to understand the dynamics of P in biosolid–amended soils, the effects of residual biosolid–borne P in soils, the way in which microorganisms may control P dynamics in biosolid–amended soils and the environmental implications of the use of biosolids as a source of P. Further research is needed to maximize biosolid–borne P uptake by crops and minimize its loss from biosolid–amended soils. The analysis of the microbiological control of P dynamics in biosolid–amended soils indicates interactions of biosolid P with other nutrients such as carbon (C) and nitrogen (N), suggesting that harmonization of the current regulation on the use of biosolids in agriculture, mainly based on total N and pollutant contents, is needed to better recycle P in agriculture.

Probabilistic modelling of prospective environmental concentrations of gold nanoparticles from medical applications as a basis for risk assessment.

BackgroundThe use of gold nanoparticles (Au-NP) based medical applications is rising due to their unique physical and chemical properties. Diagnostic devices based on Au-NP are already available in the market or are in clinical trials and Au-NP based therapeutics and theranostics (combined diagnostic and treatment modality) are in the research and development phase. Currently, no information on Au-NP consumption, material flows to and concentrations in the environment are available. Therefore, we estimated prospective maximal consumption of Au-NP from medical applications in the UK and US. We then modelled the Au-NP flows post-use and predicted their environmental concentrations. Furthermore, we assessed the environment risks of Au-NP by comparing the predicted environmental concentrations (PECs) with ecological threshold (PNEC) values.ResultsThe mean annual estimated consumption of Au-NP from medical applications is 540 kg for the UK and 2700 kg for the US. Among the modelled concentrations of Au-NP in environmental compartments, the mean annual PEC of Au-NP in sludge for both the UK and US was estimated at 124 and 145 μg kg−1, respectively. The mean PEC in surface water was estimated at 468 and 4.7 pg L−1, respectively for the UK and US. The NOEC value for the water compartment ranged from 0.12 up to 26,800 μg L−1, with most values in the range of 1000 μg L−1.ConclusionThe results using the current set of data indicate that the environmental risk from Au-NP used in nanomedicine in surface waters and from agricultural use of biosolids is minimal in the near future, especially because we have used a worst-case use assessment. More Au-NP toxicity studies are needed for the soil compartment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-015-0150-0) contains supplementary material, which is available to authorized users.

Diagnose foliar em mudas de pinhão-manso (Jatropha Curcas L.) produzidas com biossólido

O uso do biossólido na agricultura tem-se mostrado a melhor alternativa ambiental e econômica para o destino do lodo de esgoto. O objetivo deste trabalho foi avaliar o potencial nutricional do biossólido para produção de mudas de pinhão-manso em tubetes. O experimento foi realizado em casa de vegetação tendo, como substrato, esterco bovino, vermiculita e biossólido. O delineamento experimental foi o de blocos casualizados com três repetições em esquema fatorial 5 x 2, correspondendo às concentrações de biossólido no substrato (0, 10, 20, 30 e 40%) e ao tratamento ou não das sementes de pinhão-manso com fungicida. Aos 60 dias foi realizada análise foliar. Relativo às concentrações de biossólido verificou-se efeito significativo para os macronutrientes N, P, Ca, Mg e S e micronutrientes B, Cu, Mn e Zn. O tratamento de sementes teve efeito significativo para o Zn. As folhas apresentaram concentração de macronutrientes com a seguinte ordem: N > K > Mg > Ca > P > S. O acúmulo de micronutrientes apresentou a seguinte ordem: Fé > Mn >Zn > B > Cu. Há grande contribuição do biossólido nos teores de nitrogênio, enxofre e micronutrientes foliares, em plantas de pinhão-manso.

A multi-technique investigation of copper and zinc distribution, speciation and potential bioavailability in biosolids

The use of biosolids in agriculture continues to be debated, largely in relation to their metal contents. Our knowledge regarding the speciation and bioavailability of biosolids metals is still far from complete. In this study, a multi-technique approach was used to investigate copper and zinc speciation and partitioning in one contemporary and two historical biosolids used extensively in previous research and field trials. Using wet chemistry and synchrotron spectroscopy techniques it was shown that copper/zinc speciation in the biosolids was largely equivalent despite the biosolids being derived from different countries over a 50 year period. Furthermore, copper speciation was consistently dominated by sorption to organic matter whereas Zn partitioned mainly to iron oxides. These data suggest that the results of historical field trials are still relevant for modern biosolids and that further risk assessment studies should concentrate particularly on Cu as this metal is associated with the mineralisable biosolids fraction.

Effects of the application of biosolids on some chemical, biological and physical properties in an Andisol from southern Chile

An important issue for soil conservation and waste disposal is the use of biosolids in agriculture and for land reclamation. Most biosolids contain valuable nutrients that could be used to improve soil fertility. The aim of this work was to establish the effects of the application of biosolids on some chemical, biological and physi- cal properties in an Andisol from southern Chile. This study was carried out un- der farm conditions during the wheat (Triticum aestivum) growing cycle. Five land plots of 10 x 4 m each were prepared: control soil (TAT), chemical fertilisation (TAF) and applications equivalent to 30 ton biosolids/ha (TA30), 60 ton biosolids/ ha (TA60) and 90 ton biosolids ha -1 (TA90). The soil samples of both treatment and non-treatment groups were collected after the application of biosolids, after sowing and before the wheat harvest. The evaluated chemical soil parameters were modified by the application of biosolids. Base levels of organic carbon, pH and P increased. Biological activity measured by the evolution of C-CO 2 followed the sequence TA90>TA60>TA30>TAF>TAT. The physical properties evaluated, namely water infiltration rate, accumulated infiltration and water retention capacity, all increased with the increasing dose of biosolids. The results show a strong correlation between the biosolids dose applied and the change in the soil properties studied.