PHYSICO-CHEMICAL EVALUATION OF AN EFFLUENT TREATED IN ANAEROBIC BIODIGESTER REGARDING ITS EFFICIENCE AND APPLICATION AS FERTILIZER

PHYSICO-CHEMICAL EVALUATION OF AN EFFLUENT TREATED IN ANAEROBIC BIODIGESTER REGARDING ITS EFFICIENCE AND APPLICATION AS FERTILIZER. The use of biodigester for basic and environmental sanitation has large demand in Brazil. A biodigester was built to treat conjunctly the human and pig feces and urine, regarding to its future application in rural small towns. The results show that the biodigester can reduce 90% of COD and BOD and, up to 99.99% of thermotolerant coliforms. The treated effluent has variable quantities of macro- and micro-nutrients; and organic matter. However, the concentration variability of the nutrients makes difficult a dosed application into soil. The soluble salts (mainly as Na+ form) make necessary a controlled use to avoid environmental degradation.

Information programs affect attitudes toward sewage sludge use in agriculture /

Mode of access: Internet.

Land availability, crop production, and fertilizer requirements in the United States /

Prepared for U. S. Environmental Protection Agency. Office of Solid Waste Management Programs.

Utilisation agricole des eaux d'égout de la ville de Montpellier.

Mode of access: Internet.

Microbial populations and activities in sewage sludge and phosphate fertilizer-amended soil

A greenhouse study was conducted to determine the number of microbial populations and activities in sewage sludge and phosphate fertilizer-amended dark red latosoil for cultivation of tomato plants. Sewage sludge was applied at doses of 0, 10, 20, 40, 80 and 160 t ha(-1), and phosphate (P2O5) at doses of 0, 100, 200, 400 and 800 kg ha(-1). The bacterial populations increased as a function of sewage sludge and phosphate application. Fungal populations were not affected by the application of phosphate alone but were increased by the application of sewage sludge. Phosphate doses higher than 100-200 kg ha(-1) in combination with sewage sludge inhibited both bacterial and fungal growth. The responses determined by microbial counts were reflected in the microbial biomass values, with a more significant effect of sewage sludge than of phosphate or of a combination of both. These results confirm the need for a carbon and energy source (represented here by sewage sludge) for microbial growth in a soil poor in organic matter. Dehydrogenase and urease activities reflected the results of the microbial populations due to the effect of sewage sludge and phosphate, but no satisfactory result was obtained for phosphatase. Urease activity was expressed by a linear regression equation as the result of the effect of sewage sludge, and by a quadratic regression equation as the result of the effect of phosphate. All parameters investigated showed a significant correlation with bacterial counts but not with fungal counts, indicating a greater effect of sewage sludge and phosphate on bacteria than on fungi.

NUTRITIONAL BALANCE, ESSENTIAL OIL AND WOOD PRODUCTION FROM Corymbia citriodora Hill & Johnson WITH SEWAGE SLUDGE AND MINERAL FERTILIZER APPLICATIONS

The Corymbia citriodora is one of the most important forest species in Brazil and the reason is the diversity of its use, because it produces good quality wood and the leaves may be used for essential oil production. Although, there are not many studies about species and the handling effect in the nutritional balance. This study aimed to evaluate the biomass production and nutrient balance in the conventional production of essential oil and wood of Corymbia citriodora with sewage sludge application. The experiment design established was the randomized blocks, with four replicates and two treatments: 1 - fertilization with 10 tons ha(-1) (dry mass) of sewage sludge, supplemented with K and B, and 2 - mineral fertilization. It was evaluated the aerial biomass production, the nutrient export of the leaves, the essential oil and wood production at four years old. The trees that received application of sewage sludge produced 20 % more leaves biomass than the trees with mineral fertilization, resulting in larger oil production. Besides, the trees with sewage sludge application produced 14.2 tons ha(-1) yr(-1) of woody biomass that was 27 % higher than the treatment with mineral fertilization. For both treatments the N balance was negative, but treatment with sewage sludge application (-45 kg ha(-1)) was four times lower than the observed on mineral fertilization treatment (-185 kg ha(-1)). It may be concluded in this paper that the application of sewage sludge benefits the production of leaves biomass, essential oil and wood, besides result better nutritional balance of the Corymbia citriodora production system.

Arsenic biogeochemistry as affected by phosphorus fertilizer addition, redox potential and pH in a west Bengal (India) soil

This laboratory experiment systematically examines arsenic, iron, and phosphorus solubilities in soil suspensions as affected by addition of phosphorus fertilizer under different redox potential (Eh) and pH conditions. Under aerobic conditions, As solubility was low, however, under moderately reducing conditions (0, -150 mV), As solubility significantly increased due to dissolution of iron oxy-hydroxides. Upon reduction to -250 mV, As solubility was controlled by the formation of insoluble sulfides, and as a result soluble As contents significantly decreased. Soluble Fe concentration increased from moderate to highly anaerobic conditions; however, it decreased under aerobic conditions likely due to formation of insoluble oxy-hydroxides. A low pH, 5.5, led to increased soluble concentrations of As, Fe, and P. Finally, addition of P-fertilizers resulted in higher soluble P and As, even though the concentration of As did not increased after an addition rate of 600 mg P kg(-1) soil. (c) 2006 Elsevier B.V. All rights reserved.

Optimization of the electrodialytic phosphorus recovery from sewage sludge ash

Phosphorus (P) is becoming a scarce element due to the decreasing availability of primary sources. Therefore, recover P from secondary sources, e.g. waste streams, have become extremely important. Sewage sludge ash (SSA) is a reliable secondary source of P. The use of SSAs as a direct fertilizer has very restricted legislation due to the presence of inorganic contaminants. Furthermore, the P present in SSAs is not in a plant-available form. The electrodialytic (ED) process is one of the methods under development to recover P and simultaneously remove heavy metals. The present work aimed to optimize the P recovery through a 2 compartment electrodialytic cell. The research was divided in three independent phases. In the first phase, ED experiments were carried out for two SSAs from different seasons, varying the duration of the ED process (2, 4, 6 and 9 days). During the ED treatment the SSA was suspended in distilled water in the anolyte, which was separated from the catholyte by a cation exchange membrane. From both ashes 90% of P was successfully extracted after 6 days of treatment. Regarding the heavy metals removal, one of the SSAs had a better removal than the other. Therefore, it was possible to conclude that SSAs from different seasons can be submitted to ED process under the same parameters. In the second phase, the two SSAs were exposed to humidity and air prior to ED, in order to carbonate them. Although this procedure was not successful, ED experiments were carried out varying the duration of the treatment (2 and 6 days) and the period of air exposure that SSAs were submitted to (7, 14 and 30 days). After 6 days of treatment and 30 days of air exposure, 90% of phosphorus was successfully extracted from both ashes. No differences were identified between carbonated and non-carbonated SSAs. Thus, SSAs that were exposed to the air and humidity, e.g. SSAs stored for 30 days in an open deposit, can be treated under the same parameters as the SSAs directly collected from the incineration process. In the third phase, ED experiments were carried out during 6 days varying the stirring time (0, 1, 2 and 4 h/day) in order to investigate if energy can be saved on the stirring process. After 6 days of treatment and 4 h/day stirring, 80% and 90% of P was successfully extracted from SSA-A and SSA-B, respectively. This value is very similar to the one obtained for 6 days of treatment stirring 24 h/day.

Sewage sludge as nitrogen and phosphorus source for cane-plant and first ratoon crops

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assessment of the Toxic Potential of Sewage Sludge in the Midgut of the Diplopod Rhinocricus padbergi

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Agronomic Traits of Corn Fertilized with Sewage Sludge

Although research on the environmental impacts of using waste as a fertilizer is of great importance, the basic principle for using a product as fertilizer is that it should provide nutrients for plants without causing any harm to them. The objective of this study was to evaluate the agronomic traits (number of nodes, plant height, leaf number, yield, and protein content of grains) and the nutritional status of corn treated with sewage sludge. The experiment was conducted in the municipality of Jaboticabal in a Red Latosol. A randomized block design with four treatments (0, 55, 110, and 167.5 Mg ha(-1) of sewage sludge) and five repetitions was used. At 30 days after emergence (DAE), the dose of 110 Mg ha(-1) dry weight presented greater values for plant height, leaf number and stem diameter. At 60 DAE, the treatments did not affect the agronomic traits. No influence from the treatments tested was observed for protein content of grains and yield. The dose of 167.5 Mg ha(-1) showed greater weight of 100 seeds. All treatments showed nutritional imbalances. This study confirmed the agricultural potential of sewage sludge as a source of nutrients.

Impact of sewage sludge on the soil bacterial communities by DNA microarray analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Concentrations of Cu, Fe, Mn, and Zn in tropical soils amended with sewage sludge and composted sewage sludge

Sewage sludge may be used as an agricultural fertilizer, but the practice has been criticized because sludge may contain trace elements and pathogens. The aim of this study was to compare the effectiveness of total and pseudototal extractants of Cu, Fe, Mn, and Zn, and to compare the results with the bioavailable concentrations of these elements to maize and sugarcane in a soil that was amended with sewage sludge for 13 consecutive years and in a separate soil that was amended a single time with sewage sludge and composted sewage sludge. The 13-year amendment experiment involved 3 rates of sludge (5, 10, and 20 t ha-1). The one-time amendment experiment involved treatments reflecting 50, 100, and 200 % of values stipulated by current legislation. The metal concentrations extracted by aqua regia (AR) were more similar to those obtained by Environmental Protection Agency (EPA) 3052 than to those obtained by EPA3051, and the strongest correlation was observed between pseudo(total) concentrations extracted by AR and EPA3052 and bioavailable concentrations obtained by Mehlich III. An effect of sewage sludge amendment on the concentrations of heavy metals was only observed in samples from the 13-year experiment. © 2012 Springer Science+Business Media B.V.

Evaluation of biochemical and redox parameters in rats fed with corn grown in soil amended with urban sewage sludge

The increased production of urban sewage sludge requires alternative methods for final disposal. A very promising choice is the use of sewage sludge as a fertilizer in agriculture, since it is rich in organic matter, macro and micronutrients. However, urban sewage sludge may contain toxic substances that may cause deleterious effects on the biota, water and soil, and consequently on humans. There is a lack of studies evaluating how safe the consumption of food cultivated in soils containing urban sewage sludge is. Thus, the aim of this paper was to evaluate biochemical and redox parameters in rats fed with corn produced in a soil treated with urban sewage sludge for a long term. For these experiments, maize plants were grown in soil amended with sewage sludge (rates of 5, 10 and 20. t/ha) or not (control). Four different diets were prepared with the corn grains produced in the field experiment, and rats were fed with these diets for 1, 2, 4, 8 and 12 weeks. Biochemical parameters (glucose, total cholesterol and fractions, triglycerides, aspartate aminotransferase and alanine aminotransferase) as well the redox state biomarkers such as reduced glutathione (GSH), malondialdehyde (MDA), catalase, glutathione peroxidase and butyrylcholinesterase (BuChE) were assessed. Our results show no differences in the biomarkers over 1 or 2 weeks. However, at 4 weeks BuChE activity was inhibited in rats fed with corn grown in soil amended with sewage sludge (5, 10 and 20. t/ha), while MDA levels increased. Furthermore, prolonged exposure to corn cultivated in the highest amount per hectare of sewage sludge (8 and 12 weeks) was associated with an increase in MDA levels and a decrease in GSH levels, respectively. Our findings add new evidence of the risks of consuming food grown with urban sewage sludge. However, considering that the amount and type of toxic substances present in urban sewage sludge varies considerably among different sampling areas, further studies are needed to evaluate sludge samples collected from different sources and/or undergoing different types of treatment. © 2013 Elsevier Inc.

Preliminary risk assessment for parasites in municipal sewage sludge applied to land.

Mode of access: Internet.