sewage sludge

Considering the Stanford and Smith model, there was a significant difference between the potentially mineralizable carbon (C 0 ) of the treatments (TABLE 3), since there was no overlap in the estimates of the confidence intervals. The soil + sludge + straw treatment presented the highest amount of potentially mineralizable carbon, followed by the soil + straw treatment and soil + sludge treatment. This result corroborates the conclusions of Giacomini et al. (2015), who found similar results after 110 days from the beginning of incubation. These authors attributed this difference to the amounts of C added to each treatment and to the different chemical compositions of the organic materials that facilitated the use of C by microorganisms. The amount of C added by the oat straw is approximately twice as high as that added by the sewage sludge (TABLE 1).

Even though most Brazilian cities have no sewage collection and treatment system, sludge generation has increased due to population growth and socio-economic development, bringing great concern since this residue is produced in large scale. Therefore, in order to ensure a proper disposal of the sewage sludge (SS), several research lines have to be encompassed in Brazilian studies, such as agricultural uses for instance.

the large production of sewage sludge (ss), especially in large urban centers, has led to the suggestion of using this waste as fertilizer in agriculture. the economic viability of this action is great and contributes to improve the environment by cycling the nutrients present in this waste, including high contents of organic matter and plant nutrients. this study evaluated the chemical and biochemical properties of dystrophic and eutroferric Latossolos Vermelhos (oxisols) under corn and after SS application at different rates for 16 years. The field experiment was carried out in Jaboticabal, são Paulo state, Brazil, using a randomized block design with four treatments and five replications. Treatments consisted of control - T1 (mineral fertilization, without SS application), 5 mg ha -1 SS - T2, 10 Mg ha -1 SS - T3, and 20 Mg ha -1 SS - T4 (dry weight base). The data were submitted to variance analysis and means were compared by the duncan test at 5 %. sewage sludge increased P extracted by resin in both the Latossolos Vermelhos, dystrophic and eutroferric, and the organic matter content in the dystrophic Latossolo Vermelho. the waste at the rate 20 Mg ha -1 on a dry weight basis promoted increases in acid phosphatase activity in

As discussed and shown in the analysis, the induction of suppressiveness observed with the addition of sewage sludge to the pine bark-based substrate must not only be related to a single characteristic altered in the substrate, as there were significant changes in the microbial activity, nutrient concentration and pH of the substrate. Although not evaluated in the present study, evidences that changes in microbial composition and production of volatile compounds in the substrates probably contributed to the observed suppressiveness. These hypotheses are been investigated. The contribution of each factor alone in the induction of suppressiveness cannot be quantified using the findings of the present study. However, they constitute additional evidence of the efficiency of sewage sludge compost in controlling Fusarium wilt on chrysanthemum. Moreover, because the sewage sludge is rich in many macro- and micronutrients, it allows for the reduction in the amount of nutrients applied via fertigation.

residue were added to the soil. An increase in CEC caused by sewage sludge application was also suggested by Melo et al. (1994); Cavallaro et al. (1993). Who reported a CEC increase due to sewage sludge application in doses between 0 and 240 t ha -1 (dry base). Increase was attributed to the fact that organic matter has active sites, with a capacity for linking and exchanging ions, according to their pH. Carboxylic, phenol, carbonyl, alcohol, amino and other groups integrated the sites, which was directly proportionate to the quantity of organic matter. Although results from the application of increasing doses of sewage sludge on soil’s pH had a significant effect (Fig. 2), adjustment of adequate regression model failed.

Population growth coupled with urbanization, industrialization and economic development are indicative and the cause of increasing waste generation (HECK et al., 2013). Sewage sludge has been gaining more and more prominence in Brazil and worldwide, due to the large amounts generated in treatment plants. Such waste has high content of organic matter and nutrients, among other chemical elements (KUMMER, 2013), and should have a proper final disposal before its hazardous impacts on the environment.

Wastewater Treatment Stations produce sewage sludge with an average composition of 99.9 % water and 0.1 % solids. Of the total solids, 70 % are organic (proteins, carbohydrates, lipids, etc.) and 30 % inorganic (sand, salts, metals, etc.). Their disposal is one of the greatest operational problems of wastewater treatment stations (Barbosa & Tavares Filho, 2006). After treatment and processing, sewage sludge is referred to as “biosolids” and has characteristics that allow a rational and environmentally safe use in agriculture, since it contains some essential plant nutrients (N, P and micronutrients), is rich in organic matter and acts as a soil conditioner, improving the soil structure (aggregation of soil particles) (Barbosa & Tavares Filho, 2006). Agricultural recycling is therefore a more appropriate way of disposing of sewage sludge (biosolids) in technical, economic and environmental terms, given an appropriate application (Tsutiya, 1999). It is the cheapest method of recycling organic matter and nutrients (Matthews, 1998), and conditions and fertilizes the soil. In the United States, for instance, sludge has been used as fertilizer since 1927 (Neiva, 1999) and around 25 % of all biosolids produced (13,106 Mg year -1 ) is used in agriculture

Phosphorus is a macronutrient essential to life which comes from phosphate rock, a non- renewable resource. Sewage sludge from wastewater treatment plants (WWTP) is a secondary resource rich in phosphorus that can be valorized. However, organic compounds are detected in sewage sludge, due to its non-polar and hydrophobic character, being considered an environmental risk. The present dissertation aims to study the efficiency of the electrodialytic process (ED) when applied to sewage sludge aiming phosphorus recovery and organic contaminants removal. Four organic compounds were analyzed: 17 α-ethynylestradiol (EE2), bisphenol A (BPA), caffeine (Caf) and oxybenzone (MBPh). The experiments took place in an ED cell with two compartments and an anion exchange membrane, with the sludge in the cathode compartment. The experiments were carried out for three days with spiked sewage sludge (six assays). One control experiment was done without current, three experiments were carried out applying a constant current of 50, 75, and 100 mA and two experiments were carried out applying sequential currents: 50 mA, 75 mA and 100 mA and the opposite (100-75-50 mA). A qualitative and quantitative analysis of microorganisms existing in the samples was also done. At the end, the pH increased in the sewage sludge favoring phosphorus recovery. In terms of phosphorus, the highest recovery was achieved in the experiment run with 100 mA, where 70.3±2.0% of total phosphorus was recovered in the electrolyte. Generally, compounds degradation was favored by the current. Caf and MBPh achieved degradation percentages of 96.2±0.2% and 84.8±1.3%, respectively, in 100 mA assay. EE2 (83.1±1.7%) and BPA (91.8±4.6%) degradations were favored by 50 mA current. A total of 35 taxa from four different groups were identified, totalizing between 81,600-273,000 individuals per gram of initial sludges. After ED, microbial community population decreased between 47-98%. Arcella gibbosa represented 61% of the total observed organisms and revealed to be more tolerant to medium changes.

high amount transported to the soil. However, because of its insolubilization reactions under pH closer to alkalinity, the complexing power of organic matter and the fast Fe oxidation when it is released from organic matter, as described by Cunha et al. (2011), no effect was observed on soil with the sewage sludge application (Table 4). Nascimento (2012) found that, although Fe had been the metal in the highest concentration in the sewage sludge, there was no influence of the application of this residue on the available Fe content in the soil.

The nitrogen content of the compost, however, was lower than that of the SS, which can be considered a negative point with regard to agricultural use of com- post, because a larger amount of the compost could be necessary as compared to the sewage sludge in order to provide the amount of nitrogen needed for the crop, since, according to Brazilian environmental legislation (CONAMA, 2006a), the agricultural recommendation made should consider the nitrogen content present in these materials, and the amount of nitrogen recommend- ed for the crop. The concept of increased economic ra- dius of application due only to the reduction of water content is questionable, in this case. However, compost incorporates humic substances into the soil, thereby in- creasing the fertility of highly weathered soils in tropical conditions (Bertoncini et al., 2008).

The application of municipal sewage sludge (SS) in agriculture is a practice used worldwide, with benefi cial eff ects on crop productivity, such as in sugarcane in Brazil (Franco et al. 2010). Th e SS addition in the soil increases organic carbon (OC), nitrogen and phosphorus (Pires et al. 2015), besides increasing cation exchange capacity (CEC) and water retention. However, SS may carry high amounts of heavy metals and other pollutants, which can cause serious problems of plant injury, accumulation in the food chain, and surface and groundwater contamination with high environmental impacts (Saito 2007). In order to ensure that the SS does not pose any danger to the environment, the Conselho Nacional do Meio Ambiente – CONAMA (2006) legislation regulated by resolution N.375/06 was created in Brazil, together with Companhia de Tecnologia de Saneamento Ambiental – CETESB (1999) regulated by rule P4.230 in São Paulo State, to regulate the agricultural use of SS on soil.

The survival curves of the diplopods in the respective substrates are shown in igures 1, 2 and 3, and their signiicance in relation to the control group, according to the statistical test used, in Table 1. In the sludge samples whose tested concentrations were 1%, 10% and 50%, the survival of the diplopods was not altered by the increase in the concentration of the sludge, from 1% to 10%, but for the highest concentration, 50%. In the control and in the lowest concentrations, 1% and 10%, there was a higher survival rate (16.7% - 100%) with some variation, which seems to be related with the different concentrations: the lower the sludge concentration the higher the survival rate of the animals. Thus, only the survival in the highest exposure concentration differed signiicantly from the control group (p<0.05). Now, in the pure sewage sludge samples and in the 10% concentration, the survival of the animals was not affected by the lowest concentration, being that the survival rates ranged between 33.3% and 100%. However, the analysis of the pure sludge showed signiicance of the survival curves in two samples: AT-1(a) (Figure 1A) and SG (a) (Figure 2C).

A national survey carried in 2008 reported that, from a total of 5564 municipalities, 37.7% had an active WTP and only 27.2% had a WWTP. However, those numbers are about to increase according to the new environmental regulations in Brazil. Currently, the sewage sludge annual production ranges from 150 to 220 thousand tons, making its proper disposal a difficult task due to the high costs.

Sewage sludge fertilization increased the leaf Zn contents in comparison to the treatment with mineral fertilization (Table 2). Increments of Zn contents in the leaf tissues of plants grown in soils fertilized with sewage sludge have also been observed by Zuba Junio et al. (2011) in corn (Zea mays), Muhammad et al. (2013) in field mustard (Brassica campestris), Sridhar et al. (2014) in tomato (Solanum lycopersicum). As, Ba and Pb contents did not differ between the types of fertilization, and their mean values were 0.10, 0.17 and 0.15 mg kg -1 , respectively. According to Kabata-

Around the world, municipal sewage sludge is frequently applied to croplands that constitute the basis of the human food chain. Potentially hazardous trace elements may inadvertently enter human diets as a result of this practice; it is therefore imperative that plant uptake of soil-borne trace elements be evaluated. The plant availability of metals in sludge- treated soils are customarily estimated based on extraction of soil-borne metals with chemical reagents such as DTPA-TEA (mixture of 0.005M diethylenetriaminepentaacetic acid + 0.005M triethanol amine (Lopez-Valdivia et al., 2002), EDTA (0.01M ethylenediaminetetraacetic acid sodium salt (Wu et al., 2003), Mehlich I (mixture of 0.05M HCl + 0.0125M H 2 SO 4 ; Gartley et al., 2002), Mehlich III

Sewage sludge (SS) was collected at the Sewage Treatment Station of Santa Maria, RS, of the Companhia Riograndense de Saneamento (CORSAN, Rio Grande do Sul State Sanitation Agency). The sludge was processed in an extended aerobical sewage activation system and continuous flow. After treatment, the SS was deposited in drying pools, from where a sample of about 10 kg of SS was collected, placed in a plastic bucket with lid and taken to the laboratory. After homogenization, three SS subsamples were taken from the bucket for physical and chemical characterization. Dry matter (DM) was determined by oven-drying of about 50 g of SS at 65 o C to constant weight. The pH was

The use of organic wastes for agricultural fertil- ization is a growing practice worldwide following the guidelines of the modern concepts of waste management, where they should be viewed as byproducts (Wilson, 2007). Especially in developing countries, sewage sludge (SS) agricultural use is being increasingly adopted as a way of managing urban wastewater treatment chains and preventing the scarcity of water and landfill sites (Beech- er, 2008; Wang, 2011). From the perspective of agricul- tural sustainability, SS use promotes the recycling of nu- trients previously removed from the soil by crops (Elser, 2012), while reducing the use of synthetic fertilizers and their detrimental environmental effects (Childers et al., 2011). Also, SS may help prevent soil erosion (Galdos et al., 2009; Garcia-Orenes et al., 2005), increase enzymatic activity in soils (Singh and Agrawal, 2008) and decrease the incidence and viability of phytopathogenic organisms detrimental to crops (Bonanomi et al., 2010).

Use of earthworms in sewage sludge composting is a suitable technology for its management. The activity of earthworms helps to remain of aerobic condition and accelerates microbial decomposition. In this process increases the earthworm’s biomass and leaves their castings rich from nutrients (BENITEZ et al., 1999). Mixing of bulking material to sewage sludge improves earthworm’s activity and the quality of vermicompost (DOMINGUES et al., 1999). Gondek and Filipek-Mazur (GONDEK; FILIPEK-MAZUR, 2001) used from conifers saw dust, shredded cardboard, and wheat straw as bulking agents with the mixing proportion of 15% for vermicompost production from sewage sludge. Arumuga et al. ( ARUMUGA et al., 2004), in India, used from the mixture of sewage sludge, rice straw and manure for vermicompost production. Vigueros and Camperos ( VIGUEROS; RAMIREZ-CAMPEROS, 2002) used from water hyacinth as bulking material for vermicomposting of sewage sludge. Eastman et al. (EASTMAN et al., 2001) showed that fecal coliforms bacteria and helminthes ova in were significantly lower in vermicompost compare to compost produced from biosolids and vermicomposting is an alternative method for class a compost production. The aims of this study were: 1) to determine chemical composition of produced vermicomposts from mixing of various bulking material with sewage sludge 2) to investigate their quality and suitability as organic fertilizer

Sugarcane is a semi-perennial crop harvested several times after each planting. New plants grow from the stubble (so-called cane-ratoon) left behind after harvesting the initially planted crop (so-called cane-plant or first regrowth). So, it is agronomically advisable to evaluate the effects of fertilizer accumulation during the entire production phase of each planting, not just for a single harvest. In this sense, Orlando Filho et al. (1999) reported a residual effect of the mineral N fertilizer applied to cane-plant on ratoon vigor, causing increased yields in subsequent cuttings. Besides, studies on the mineralization of sewage sludge demonstrate that approximately 30 % of organic N is mineralized in the first year of cultivation (Boeira et al., 2002) and 10 % in the second year (Cogger et al., 2004), calling for an evaluation of the residual sludge effect to formulate recommendations for supplementary mineral fertilization of cane fields. However, there are very few studies in Brazil analyzing the effects of continued sludge application on sugarcane (Oliveira, 2000; Có Junior et al., 2008; Franco et al., 2008), and none of these evaluated the residual effect of sludge applied to cane-plant on the second harvest (first ratoon).

Several authors consider the sludge residue as low-K, as it is found predominantly in the ionic form, which tends to remain in solution during the process of wastewater treatment, and chemical complementation with this element is constantly recommended (Bueno et al., 2011; Guedes et al., 2006; Simonete et al., 2003). However, in the present study, K could not be considered a limiting element of productivity, because the quantities added into the soil by the treatments solarized, composted, vermicomposted and limed were, respectively: 0.7, 4.2, 3, 1 and 8.9 times the recommended. Although the amount of K applied was lower than recommended in the solarized sewage sludge treatment, no deficiency symptom was detected, but it is worth mentioning the high initial levels of K in the soil, ranging 229-117 mg dm -3 in the depth of 0-40 cm.