Sanitary landfills, created for the disposal of solid waste, usually are developed into parks after they are closed. However, soil amelioration with organic matter is usually needed to restore fertility and promote revegetation. Sewage sludge creates a massive waste disposal problem. The use of composted sewage sludge (BIOSOLID) as a soil conditioner might restore the soil fertility at landfill sites and simultaneously alleviate the need for sewage sludge disposal. We applied BIOSOLID to waste landfill soil and evaluated its effects on soil properties and tree growth in a field experiment. BIOSOLID improved soil characteristics including moisture, organic matter, and nitrogen content and also increased tree height and diameter at breast height.Physiological measures, such as chlorophyll content and photosynthetic rate, showed positive responses in trees grown in BIOSOLID treatments. Heavy metal concentrations in soil and tree leaves after applying compost did not differ from concentrations measured at control sites. Therefore, we conclude that the use of BIOSOLID in waste landfills would be an efficient, environmentally beneficial, and cost-effective method to restore the conditions of landfill soil for plants.

Background: The application of BIOSOLID as a fertilizer in agricultural cultivation is a common practice in many countries. This study investigates the effects of sewage sludge and compost usage on soil chemical properties and Zea maysnutrition in comparison with those of iron and manganese sulfate solution. The experiment was carried out in a completely randomized block design with the following treatments: sewage sludge and compost with three levels (0, 25 and 50 t ha-1) and iron and manganese sulfate solution (1 g l-1 solution) with three replications.Results: The application of sewage sludge (50 t ha-1) had highly significant (P<0.01) positive effects on cation exchange capacity and organic matter, total nitrogen, phosphorus, iron and manganese diethylenetetramine-pentaaceticacid- extractable in soil, and nitrogen, phosphorus, iron and manganese in plant. Also, compost application (50 t ha-1) increased significantly (P<0.01) the electrical conductivity in soil and potassium in soil and plant. Dry biomass increased significantly (P<0.01) from 7.7 to 28.7 g per pot with sewage sludge application (50 t ha-1).Conclusions: Application of BIOSOLID as fertilizer sources has become a common practice in Iran, especially in the agricultural lands. The reuse of these nutrients had some beneficial effects on soil fertility, such as increased cation exchange capacity, pH, organic matter, total nitrogen, phosphorous, iron and manganese. However, these benefits were limited by the presence of some potentially toxic trace metals in BIOSOLID.

Purpose Organomineral fertilizers formulated from different organic sources have been studied for the fertilization of several crops. Filter cake is currently one of the most used sources of organic matter; however, sewage sludge also presents characteristics of agronomic interest, being one of the major environmental problems in Brazil. In this sense, the efficiency of pelletized organomineral fertilizers produced with both sources were evaluated for the development of soybean under different fertilization levels. Methods The experiment was carried out in greenhouse conditions. The soil was characterized as Red Eutrophic Oxisol. The experimental design was randomized block design in a 2 × 4 + 2 factorial scheme, corresponding to two sources of organic matter (sugarcane filter cake and treated sewage sludge), in four doses (50, 75, 100 and 125% of recommendation for soybean cultivation), as well as a mineral fertilization and no-fertilization treatments. The plant development was evaluated (stem diameter, plant height and chlorophylls a and b) at 30, 60 and 90 days after sowing. Results Organomineral fertilizers formulated from sanitized sewage sludge or sugarcane filter cake promote a higher soybean plant height in relation to mineral fertilizer, especially after the middle of the crop cycle. The level of fertilization referring to 75% of the recommended dose for soybean, when made with sanitized sewage sludge or filter cake, resulted in large stem diameter in relation to mineral fertilization. Conclusion Organomineral fertilizers based on sanitized sewage sludge or filter cake promote increases in soybean characteristics up to 90 days.

The effective parameters on Ohmic heating in static system containing BIOSOLID-water were studied. The effects of distribution of particles, salinity and electric field strength on electrical conductivity, profiles of temperature, heat generation have been investigated.The experimental data verification with simulation results using computational fluid dynamics (CFD) method were carried out. Governing equations (heat transfer and electrical equations) were discretized with finite element method.The experimental data and CFD results showed that in Ohmic heating process, the current diffusion in all the products is faster than traditional methods and the diffusion rates are equal for both BIOSOLID-liquid phases.

Purpose: Sewage sludge samples from a water treatment plant in Nigeria were subjected to an in-vessel composting (using sawdust as a bulking agent) and thermal sludge processing to improve its quality for agricultural applications.Methods: Treated samples were analyzed for physicochemical and microbiological properties using standard analytical and aerobic culture protocols.Results: Microbiological analysis of the initial fresh mixture (sewage sludge/sawdust) showed that the total heterotrophic bacteria was 1.179 106 CFU/g of fresh compost, coliforms 4.79 104 CFU/g, Salmonella sp., and Shigella sp.7.39 104 CFU/g, yeasts and moulds 9.0 9 104 CFU/g.These values were significantly (p=0.05) reduced after 40 days of in-vessel composting to 4.39 104 CFU/g for total heterotrophic bacteria, 7.49 102 CFU/g for coliforms, while yeasts and moulds, Salmonella and Shigella sp. were not detected in the final compost. The results of the physicochemistry revealed variation in pH, temperature, and nutrients status of treated sludge.Conclusion Salmonellasp., Staphylococcus aureus, and Shigellasp. were eliminated, while a 2-log reduction in coliform counts occurred after 40 days of composting.Composting had a better processing impact by increasing the ash as well as reducing the carbon/nitrogen ratio of treated sludge, while thermal processing improved the sulfate and phosphate components of treated sludge. The treated sludge (BIOSOLIDs) met the permissible limits of microbiological and nutritional standards recommended by US EPA for land application of sludge and could, therefore, be used as a biofertilizer, soil conditioner and also for land reclamation.

In this experiment the use of different organic waste materials - poplar tree bark, palm fibre and sewage sludge compost (BIOSOLID) - as substrates in the production of ornamental plants was studied, with a special interest in the suitability of palm fibre as growing substrate for conifer plants. The plant species tested were Pinus densiflora, Cupressus arizonica and C. sempervirens and the substrate mixtures were: (1) poplar tree bark, (2) poplar tree bark with 15% of sewage sludge compost, (3) poplar tree bark with 30% of sewage sludge compost, (4) palm fibre, (5) palm fibre with 15% of sewage sludge compost and (6) palm fibre with 30% of sewage sludge compost. The substrates were physically and chemically well characterized and 75-cm plants were grown on them for one year. For each species, the experimental design consisted of six random blocks with 60 plants per substrate grown in 7-I capacity pots. The plant and substrate status were periodically tested during the experiment. Since BIOSOLID recycling is the main objective of the present work, mixtures with 30% of composted sewage sludge will be the most convenient substrate to use. Plant growth in palm fibre substrates mixed with BIOSOLID showed similar results as those grown in poplar tree bark based substrates. For C. sempervirens and C. arizonica, a mixture of poplar tree bark or palm fibre and 30% BIOSOLID compost in volume gave the best results. However, the lower cost of the poplar tree bark than the palm fibre substrate indicated the use of the PB+30% CSS. Also, the results showed that palm fibre substrate alone was not a good growing media for Cupressus plants.

This study was conducted to investighate the adsorption of Cadmium from aqueous solutions by using the powder of excess sludge (BIOSOLID) from municipal wastewater, at 24 to 26oC, a pH value of 2 to 6, over a contact time of 5-420 minutes, and at 50 to 300 rpm stirring rate in a batch reactor on the laboratory scale. The pretreatment of BIOSOLIDs consisted of dewatering, grinding, and grainsizing with sieves (mesh dimensions between 50 and 120). According to the results, the best conditions for BIOSOLIDs to adsorb Cadmium was pH=4, 120 minutes of contact time, and a stirring rate of 200 rpm. Cadmium adsorption kinetics followed the pseudo second order model. Maximum equilibrium adsorption was observed after two hours. The adsorption isotherm was in accordance with the Langmuir model. Maximum Cadmium adsorption capacity of BIOSOLIDs (qmax) was estimated at 0.38 m-mol/g of dry BIOSOLID (41.5 mg/g) and the Langmuir constant (kd) was found to be 0.1044 m-mol/lit (11.37 mg/lit).

Information of P fractions in sewage sludge treated soils is necessary for better management of land application of organic amendments. The purpose of this study was to evaluate the effect of sewage sludge on the forms and distribution of P in a calcareous soil using a sequential fractionation procedure. A greenhouse experiment with six levels of sewage sludge (0, 22.5, 45, 90, 180 and 360 ton ha-1) was conducted as a completely randomized design with four replications with wheat plant for 90 days. In comparison with the control, sewage sludge application significantly increased all P forms. Among various P fractions, labile P showed the largest increase. In the control soil, the various P fractions could be ranked in the following order: HCl-P>OAc-P>CBD-P>NaCl-NaOH-P>Labile-P. In contrast, the order in BIOSOLID-treated soils follows: HCl-P>OAc-P>Labile-P>CBD-P> NaCl-NaOH-P. In general, the results demonstrated that the dominance of inorganic P forms in sewage sludge. Inorganic P forms represented 80% of total P in BIOSOLID-treated soils and 57% in the control. In control soil and BIOSOLID-treated soils, Ca-associated Pi was the dominant fraction. Application of sewage sludge significantly increased the concentration of P in shoots of wheat compared with the non-manured control.

Background: There are high numbers of human pathogenic microorganisms existing in municipal sewage sludge including bacteria, viruses, and protozoan parasites. Therefore, BIOSOLIDs could be considered as the environmental contaminants and a major carrier of disease causing diseases. As the etiological agents of acute gastroenteritis and hepatitis, enteroviruses are one of the most significant enteric pathogens affecting human health. The aim of this research was to detect the enteroviruses in the sludge of two wastewater treatment plants (WWTP) in Isfahan, Iran.Methods: In this study, 30 BIOSOLID samples were taken from two WWTPs. After measuring the temperature, the samples were transported to the laboratory and analyzed for total solids (TS), volatile solids (VS) and enteroviruses according to the test methods of Standard Methods (part 9510F) and manual of Control of Pathogens and Vector Attraction in Sewage Sludge from Environmental Protection Agency (EPA) appendix F.Findings: Average temperature of the samples was about 23o C. The average number of enteroviruses was 4.5×106 and 7.7×105 plaque-forming unit (PFU) in 4 grams sludge for two WWTPs, respectively. The statistical analysis revealed a significant association between the enteroviruses and volatile solids. The number of enteroviruses was higher in summer in comparison to autumn.Conclusion: The results showed that all the BIOSOLID samples could not meet the Class A pathogen requirements for enteroviruses and poses a potential health risk for people exposed to. Therefore, restrictions in land application of BIOSOLIDs are required in order to protect public health and the environment. Moreover, special BIOSOLID treatment procedures must be used to reduce pathogens and to meet land-application standards.