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The application of sewage sludge or biosolids on soils has been widespread in agricultural areas. However, depending on their characteristics, they may cause increase in heavy metal concentration of treated soils. In general, domestic biosolids have lower heavy metal contents than industrial ones. Origin and treatment method of biosolids may markedly influence their characteristics. The legislation that controls the levels of heavy metal contents in biosolids and the maximum concentrations in soils is still controversial. In the long-term, heavy metal behavior after the and of biosolid application is still unknown. In soils, heavy metals may be adsorbed via specific or non-specific adsorption reactions. Iron oxides and organic matter are the most important soil constituents retaining heavy metals. The pH, CEC and the presence of competing ions also affect heavy metal adsorption and speciation in soils. In solution, heavy metals can be present either as free-ions or complexed with organic and inorganic ligands. Generally, free-ions are more relevant in environmental pollution studies since they are readily bioavailable. Some computer models can estimate heavy metal activity in solution and their ionic speciation. Thermodynamic data (thermodynamic stability constant), total metal and ligand concentrations are used by the GEOCHEM-PC program. This program allows studying heavy metal behavior in solution and the effect of changes in the conditions, such as pH and ionic strength and the application of organic and inorganic ligands caused by soil fertilization. ; A aplicação agrícola de lodos de esgoto ou biossólidos tem se tornado prática comum, mas pode causar o acúmulo de metais pesados nos solos, dependendo das características desses resíduos. Em geral, biossólidos de origem doméstica apresentam teores de metais inferiores aos dos oriundos de descarga industrial. A origem e o processo de tratamento influenciam as características desses materiais. A legislação que controla os níveis de metais pesados presentes nos biossólidos e a concentração máxima nos solos é controversa. O comportamento dos metais pesados em longo prazo, após o término da aplicação de biossólidos, não é bem conhecido. Nos solos, os metais pesados podem ser adsorvidos por meio de reações de adsorção específica e/ou não específica. Dentre os componentes que retém metais pesados, destacam-se os óxidos de Fe e a matéria orgânica. O pH, a CTC e a presença de cátions afetam a adsorção e a especiação iônica de metais pesados nos solos. Em solução, os metais encontram-se como íons livres e/ou formam complexos com ligantes orgânicos e inorgânicos. As espécies-livres são mais importantes em estudos de poluição ambiental, pois correspondem às formas prontamente biodisponíveis. Alguns programas computacionais calculam a atividade dos metais em solução e sua especiação iônica. O programa GEOCHEM-PC utiliza uma base de dados termodinâmicos (constante de estabilidade termodinâmica), a concentração total do metal e dos ligantes em solução. Isso permite observar o comportamento dos metais em solução e a resposta dos mesmos às mudanças nas condições do meio, tais como a variação do pH e da força iônica e a adição de ligantes orgânicos e inorgânicos via adubação.

Le volume élevé de biosolides municipaux et industriels (BS) produits dans le monde entier est une source de préoccupation majeure pour les écologistes. Actuellement, la production mondiale de BS est estimée à environ 100 à 125 millions de tonnes par an et devrait augmenter continuellement. Au Canada, 6,6 millions de tonnes de BS stabilisés secs sont produites chaque année par plus de 3 500 stations d'épuration des eaux usées (STEP). La gestion et l'élimination des BS sont très préoccupantes pour de nombreuses municipalités, car cela peut représenter plus de la moitié du coût total du traitement des eaux usées. La valorisation des BS pour la production de biogaz présente un grand avantage. En effet, la digestion anaérobie des BS peut être utilisée pour produire du biogaz comme combustible si celui-ci est correctement collecté et purifié. Outre cet avantage, les BS représentent une menace environnementale à travers la production de gaz à effet de serre (GES), et la production de lixiviat contenant de nombreux contaminants organiques (incluant des contaminants organiques à l'état de traces (TrOCs), tels que les composés pharmaceutiques actifs (PhACs) et pesticides). Ainsi, à partir des sites d'enfouissement et de l'amendement des sols avec les BS municipales, ces contaminants peuvent se retrouver dans les eaux souterraines. Pour remédier à cela, le Québec a mis en place des politiques strictes en matière d'élimination des BS. On compte parmi les mesures prises l'interdiction du déversement des BS dans les décharges et établit une taxe verte qui est prélevée en fonction de l'inflation pour chaque tonne de BS incinérée ou mise en décharge au Québec. Cependant, avec l'aide de technologies de bioprocédés avancées, ces BS peuvent être traités et utilisés simultanément comme matière première pour la production de produits de grande valeur ou de précurseurs de produits de grande valeur. Ce travail de recherche fournit une évaluation des principales méthodes d'élimination (réduction du volume et des contaminants) et passe en revue l'état des processus biotechnologiques, en particulier pour la digestion aérobie pour la production d'enzymes hydrolytiques et lignolytiques à partir des BS. En premier lieu, l'impact des microorganismes endogènes a été étudié avec ou sans co-traitement. En ce sens, divers traitements comprenant l'utilisation de microorganismes indigènes présents dans les BS, l'effet combiné d'un prétraitement enzymatique, la biostimulation par l'ajout d'une source externe de carbone et l'effet synergique de la biostimulation et du prétraitement enzymatique ont été étudiés pendant 28 jours. En raison de diverses stratégies de traitement, une réduction totale des solides en suspension de 12% à 23%, une élimination des PhACs de 44% à 62% et une élimination des pesticides d'environ 10% à 54% ont été observées. Aussi, pour améliorer l'élimination des solides en suspension des PhACs et pesticides, l'effet de quatre stratégies de prétraitement différentes (ultrasonication, congélation-décongélation, addition enzymatique et traitement alcalin), suivis d'une bioaugmentation avec la souche de bactérie Bacillus subtilis a été étudiée. Après 28 jours de traitement, la bioaugmentation a amélioré l'élimination totale des solides en suspension par 8 à 54% et une l'élimination des PhACs par 21 à 80% et une l'élimination des pesticides par 22 à 76%. La production d'un cocktail d'enzymes extracellulaires (ex. : laccase, peroxydase, glucose oxydase, lipase, phosphatase, estérase…etc.) à la suite de la bioaugmentation des BS avec B. subtilis a été observée. Ces enzymes peuvent être impliquées dans l'élimination des contaminants présents dans les BS ainsi que dans la réduction des solides observée. Cette étude est une approche bio-intégrée, où les enzymes produites lors de la digestion aérobie des BS ont été évaluées pour l'élimination des contaminants organiques présents dans les BS issus du traitement des eaux usées municipales. Pour souligner cela, la bioaugmentation des BS avec la souche de champignon Aspergillus niger a été évaluée dans le but de produire une enzyme d'intérêt telle que la glucose oxydase (GOD). La GOD sécrétée par A. niger, a été utilisée pour le processus d'oxydation avancé basé sur le bio-Fenton pour la dégradation de 15 PhACs d'intérêt dans l'eau. En somme, l'utilisation des BS comme substrat par les microorganismes étudiés a permis d'une part de diminuer les contaminants organiques et, d'autre part, de réduire le volume des BS. ; Abstract : The high volume of municipal and industrial biosolids (BS) produced all over the world is a cause of major concern to the environmentalists these days. Currently, the worldwide production of BS is estimated to be around 100-125 million tonnes per year and is expected to increase continuously. According to Canadian context reported on, 6.6 million tonnes of dry stabilized BS are generated yearly by more than 3500 wastewater treatment plants (WWTPs). Management of BS is primarily handled as a technical matter. The disposal of BS is of great concern for many WWT facilities because it accounts for over half of the total cost of wastewater treatment. BS disposal in landfill sites leads to a great advantage of biogas generation by anaerobic digestion which can be used as a fuel if the biogas is properly collected. Apart from adding advantages, it poses environmental threat such as trace organic contaminants (TrOCs), green house gases (GHGs) production, potential contaminant leachate into the ground water system at the landfill site as well as soil amendment of municipal BS . Stringent laws in BS disposal are followed in Quebec which focuses on restraining from the dumping of BS in landfills and green tax is levied based on the inflation for each ton of biosolid that is incinerated or landfilled in Quebec. However, with the help of advance bioprocess technologies these biosolids can be treated and simultaneously used as a raw material for the production of high value products or high value product precursors. This current research work delivers an assessment of the leading disposal methods (volume and contaminant reduction) and reviews the state of biotechnological processes, particular to aerobic digestion for the production of hydrolytic and lignolytic enzymes from BS. During aerobic digestion, various pretreatments including utilization of indigenous microbes present in BS, the effect of an enzymatic pretreatment, biostimulation by the addition of an external carbon source and the synergic effect of biostimulation and enzymatic pretreatment were studied for 28 days. As a result of various treatment strategies, the total suspended solids reduction of 12-23% ,total PhACs removal of 44-62% and total pesticides removal around 10- 54% were observed. Further, to enhance the total suspended solids, total PhACs and total pesticides removal, effect of four different pre-treatment strategies (ultrasonication, freezethawing, enzymatic and alkaline addition) subsequent bioaugmentation with Bacillus subtilis for IV 28 days were studied. Impact of bioaugmentation improved the total suspended solids removal by 8-54%, total PhACs removal by 21-80% and total pesticides removal by 22-76%. The production of enzymatic cocktail by bioaugmented along with indigenous microorganisms, which contain high laccase, peroxidase, glucose oxidase, lipase, phosphatase, esterase activities and other activities related to elimination of contaminants present in the BS. This study is biointegrated approach, where the enzymes producing during aerobic digestion of BS is evaluated to reduce the contaminants present in water or wastewater. To emphasize that, bioaugmentation of Aspergillus niger to BS to produce glucose oxidase (GOD), which was utilized for bio-Fenton based advanced oxidation process for the partial removal of 15 pharmaceutically active compounds in water. Therefore, the use of BS residuals as a substrate can decrease the contaminants on the one hand and, on the other hand, it can reduce the volume of BS.

AbstractThis paper describes a soil‐incubation study which was carried out to examine the effects of (a) phosphorus removal during the treatment of domestic sewage and (b) treating sewage sludge to an enhanced status, on the phosphorus fertiliser value of biosolids which are used in agriculture. Phosphorus‐enriched and conventional dewatered digested biosolids, thermally‐dried pellets and granules, and digested and thermally‐hydrolysed liquid sludges were incorporated into two soil types with contrasting physico‐chemical properties. Plant‐available phosphorus in soil was assessed after incubation by a standard chemical‐extraction procedure. Sludge from biological‐P removal had the highest phosphorus extract‐ability in soil whereas iron dosing slightly reduced or had no effect on phosphorus release from conventionally‐treated biosolids, depending upon the type of soil. High‐temperature drying significantly reduced the extractable‐P content in sludge by 20–60%, compared with dewatered digested cake, and release from thermally‐dried biosolids declined further with iron enrichment. Extractable‐P recovery was greater from all types of biosolids when mixed with calcareous soil, compared with a loamy sand. A preliminary investigation of phosphorus mineralogy in biosolids, using advanced analytical techniques, is also described.

AbstractThe escalating generation of biosolids and increasing regulations regarding their safe handling and disposal have created a great environmental challenge. Recently, biosolids have been incorporated into the hydrolysis step of a two-step thermal lipid conversion process to act as water replacement in the production of renewable chemicals and fuels. Here, the hexane extract recovered from hydrolysis of biosolids, lipids from brown grease hydrolyzed using either water (control) or biosolids as a water replacement, was pyrolyzed at 410–450 °C for 2 h. The product distribution and composition were not significantly different when biosolids were used to hydrolyze brown grease instead of water. The liquid product consisted mainly of alkanes, alkenes, aromatics, and cyclic compounds similar to those in petroleum-derived liquid fuels. However, the use of biosolids as a water substitute resulted in a significant increase in sulphur content of the pyrolysate, which will necessitate processes to reduce the sulphur content before or after pyrolysis. Nevertheless, the pathways proposed in this paper are considered as potentially economically viable approaches to not only resolve the issues associated with disposal of biosolids but also to produce renewable hydrocarbons for fuel and chemical applications.

Abstract Background Fertilisation of land with processed sewage sludges, which often contain low levels of pathogens, endotoxins, and trace amounts of industrial and household chemicals, has become common practice in Western Europe, the US, and Canada. Local governments, however, are increasingly restricting or banning the practice in response to residents reporting adverse health effects. These self-reported illnesses have not been studied and methods for assessing exposures of residential communities to contaminants from processed sewage sludges need to be developed. Methods To describe and document adverse effects reported by residents, 48 individuals at ten sites in the US and Canada were questioned about their environmental exposures and symptoms. Information was obtained on five additional cases where an outbreak of staphylococcal infections occurred near a land application site in Robesonia, PA. Medical records were reviewed in cases involving hospitalisation or other medical treatment. Since most complaints were associated with airborne contaminants, an air dispersion model was used as a means for potentially ruling out exposure to sludge as the cause of adverse effects. Results Affected residents lived within approximately 1 km of land application sites and generally complained of irritation (e.g., skin rashes and burning of the eyes, throat, and lungs) after exposure to winds blowing from treated fields. A prevalence of Staphylococcus aureus infections of the skin and respiratory tract was found. Approximately 1 in 4 of 54 individuals were infected, including 2 mortalities (septicaemia, pneumonia). This result was consistent with the prevalence of S. aureus infections accompanying diaper rashes in which the organism, which is commonly found in the lower human colon, tends to invade irritated or inflamed tissue. Conclusions When assessing public health risks from applying sewage sludges in residential areas, potential interactions of chemical contaminants with low levels of pathogens should be considered. An increased risk of infection may occur when allergic and non-allergic reactions to endotoxins and other chemical components irritate skin and mucus membranes and thereby compromise normal barriers to infection.

Approximately 3.4 million tons of biosolids, dry weight, are land-applied annually to farms, forests, rangelands, mine lands, and other land use types. Biosolids are defined by the U.S. Environmental Protection Agency (EPA) as ""the primarily organic solid product yielded by municipal wastewater treatment processes that can be beneficially recycled"" as soil amendments. Concerns for potential human health effects from land-applied biosolids can be addressed through the conduct of a risk assessment. This book focuses on the systematic planning step (a ""problem formulation"" defining the major

Urban wastewater treatment leads to the generation of large quantities of biosolids. Accumulation of biosolids is a problem of environmental relevance due to the existence of heavy metals in the biosolids. Determination of total metal in biosolid provides information relating pollution levels. Determination of their mobilization capacity and behaviour in the environment is an important task. An experimental approach commonly used for studying the mobility, transport and bioavailability of metal in biosolids is the use of selective sequential extraction procedure. In the present study an attempt has been made to study the heavy metal properties in biosolid samples collected from urban wastewater treatment plants located at Mysore, Karnataka. Few heavy metals selected for the present study are cadmium, chromium, copper, iron, nickel and zinc. The concentration of these metals in biosolids and their partition in different fractions are studied. The speciation of metals based on the sequential extraction scheme was carried out. The concentration of heavy metals is lower than that established by European legislation. The residual fraction has the maximum percentage of heavy metals whereas, only a small fraction of heavy metals (Fe, Zn and Cd) are extracted in the most soluble fractions, exchangeable and carbonate fractions.