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Tratamento anaeróbio de resíduos orgânicos com baixa concentração de sólidos

The process of anaerobic digestion of organic solid wastes with low concentration of solids is accomplished with substratum containing on average about 5% (percentage in weight) of total solids. The problems of technical order associated to this kind of treatment, are related to the study of the reactors configurations that can make possible a good transformation efficiency of the organic matter in a relatively short period of time. Therefore, in this work it was studied the process of anaerobic digestion of organic solid wastes with low concentration of solids in a compartmented anaerobic reactor (CAR). The compartmented anaerobic reactor had unitary capacity of 2200 liters. The reactor was fed daily with fresh organic solid wastes and with 90 days of solid retention time. The average efficiency of transformation of VTS was of 75% and the biogas produced contained on average 60% of methane gas.

The removal of ammonia from sanitary landfill leachate using a series of shallow waste stabilization ponds

This study evaluated the efficiency of a shallow (0.5 m deep) waste stabilization pond series to remove high concentrations of ammonia from sanitary landfill leachate. The pond system was located at EXTRABES, Campina Grande, Paraiba, Northeast Brazil. The pond series was fed with sanitary landfill leachate transported by road tanker to the experimental site from the sanitary landfill of the City of Joao Pessoa, Paraiba. The ammoniacal-N surface loading on the first pond of the series was equivalent to 364 kg ha(-1) d(-1) and the COD surface loading equivalent to 3,690 kg ha(-1) d(-1). The maximum mean ammonia removal efficiency was 99.5% achieved by the third pond in the series which had an effluent concentration of 5.3 mg L(-1) ammoniacal-N for an accumulative HRT of 39.5 days. The removal process was mainly attributed to ammonia volatilization (stripping) from the pond surfaces as a result of high surface pH values and water temperatures of 22-26°C. Shallow pond systems would appear to be a promising technology for stripping ammonia from landfill leachate under tropical conditions.

Tratamento de resíduos sólidos de centrais de abastecimento e feiras livres em reator anaeróbio de batelada

Significant quantity of organic solid waste with favorable characteristics for integral utilization in anaerobic biostabilization is produced in free markets and supply centers. The process is conducted in anaerobic batch reactors (ABR), with detention time of solids varying from 250 to 300 days, producing biogas with about 60% of methane, besides the partially biostabilized organic compost as the final product. In this study, the organic solid waste used was typically of vegetables, originated from the supply centers, free markets and sanitary wastewater sludge. The experimental system used was basically constituted of a batch anaerobic reactor of 2200 L capacity, besides the other complementary devices. The experimental system was installed and monitored during the period of January to September 2001 at the Experimental Station for Biological Treatment of Sanitary Sewage, located at Tambor, Campina Grande, in the State of Paraiba, Brazil. During the process of monitoring the systematic characterization of the solid, liquid and gaseous fractions were realized. After analyzing the data, the feasibility of this alternative treatment, was evidenced although the economic viability in comparison to other technological alternatives of treatment of organic solid waste remains to be tested.

Tratamento anaeróbio de resíduos sólidos orgânicos com alta e baixa concentração de sólidos

In this study the anaerobic treatment of organic solid waste with high and low concentrations of solids was studied. The experimental system comprised of two reactors, with unitary capacity of 2,200 L, while the used substrate was composed of solid vegetable waste and sludge. One of the reactors was loaded with substrate containing 20% of total solids and the other with only 5% of total solids on weight basis. It was verified that, for the substrate containing 5% of total solids, the retention time of solids required for 80% reduction of the applied COD mass was 90 days, during which the methane gas production rate was of 0.25 Nm3 kg-1 CODApplied; whereas in the substrate containing 20% of total solids, the retention time of solids required for biostabilization of 80% of the mass of applied COD was 270 days, with a methane gas production rate of 0.1 Nm3 CH4 kg-1 CODApplied.

Compostagem aeróbia conjugada de lodo de tanque séptico e resíduos sólidos vegetais

The sanitary sludge, principal byproduct of sewage treatment, constitutes one of the major municipal environmental problems of the present time. The present study was aimed to evaluate the composting of septic tank sludge (SS) and vegetable solid waste (VW) and to determine the importance of the temperature for the process of sanitization of the treated substrate. The experiment, entirely randomized with three treatments and three repetitions, constituted of nine aerobic reactors with 100 L capacity. The proportions of the wastes utilized were T1: 100%VW; T2: 5%SS + 95%VW; T3: 10%SS + 90%VW. The conjugated composting showed to be a feasible alternative for destruction of helminth eggs and stabilization of the wastes. The temperature, pH and ecological relations present in the reactors were fundamental for this purpose.

Desempenho da cultura do arroz irrigado com esgotos sanitários previamente tratados

Com o presente trabalho, objetiva-se avaliar o desempenho da cultura do arroz, irrigada com efluentes de esgoto sanitario provenientes de tanque septico e de lagoa de estabilizacao, tomando-se como referencial comparativo a mesma cultura irrigada com agua de abastecimento em solos fertilizados com adubos minerais e sem adubo mineral. No experimento foi utilizada a cultivar Diamante, originada da EMBRAPA Meio Norte, e o sistema experimental era constituido por 4 tabuleiros com 10 m2 de area unitaria, irrigados por inundacao intermitente, procurando-se manter sempre uma media de 5 cm de lâmina liquida a cada dois dias, durante o periodo de 4 meses. A analise dos dados demonstra que a produtividade da cultivar Diamante, irrigada com efluente de tanque septico, foi superior a produtividade da mesma cultivar irrigada com agua de abastecimento em solo com adubacao mineral. Salienta-se, ainda, que os graos da cultivar irrigada com efluente do tanque septico nao apresentaram, em nenhum exame, indicadores de contaminacao fecal.

Bioestabilização anaeróbia de resíduos sólidos orgânicos em reatores de batelada

O processo de bioestabilizacao anaerobio pode ser empregado para o tratamento de uma grande variedade de substratos, dentre os quais pode-se destacar os residuos solidos orgânicos. Neste trabalho, o processo de bioestabilizacao anaerobio foi utilizado, quando do tratamento de residuos solidos orgânicos putresciveis de origem urbana e rural. Os residuos de origem urbana eram constituidos, basicamente, de restos de fruta, verduras e folhagens, enquanto o rumen bovino era o residuo rural utilizado. As proporcoes de rumen empregadas foram de 5, 10 e 15% (percentagem em peso).O trabalho foi realizado em um sistema experimental, constituido basicamente por quatro reatores anaerobios de batelada, com capacidade unitaria de 20 L. A eficiencia do processo foi determinada tomando-se, como parâmetros avaliativos, os solidos totais volateis (STV), a demanda quimica de oxigenio (DQO) e o nitrogenio total Kjedhal (NTK). Salienta-se que este processo de tratamento bioestabiliza os residuos orgânicos putresciveis, tornando-os biodisponiveis de aplicacao nos solos, alem de produzir metano, que pode ser utilizado como fonte alternativa de energia para fins domesticos e industriais. A analise dos dados deste trabalho demonstra que o desempenho do processo de bioestabilizacao foi funcao do percentual de rumen utilizado.

Anaerobic treatment of organic wastes with low concentration of solids

The object of this study was to evaluate the use of a compartmented anaerobic reactor to treat organic solid waste with low concentration of solids. The reactor with a total capacity of 2.200 liters, divided into 6 equal chambers, was operated at a solid retention time of 90 days. The organic solids used to feed the reactor were comprised by vegetable residues and sanitary sludge in the proportion 80% and 20% respectively. The mixture of these two types of residues after the humidity correction to 95% (percentage by weight) was used to feed the reactor. The removal efficiency of carbonaceous material was approximately 80% at an organic loading of 9.3 kg residual organic solids m-3 d-1. The rate of biogas production was 5.6 L kg-1substrate (wet weight) with a methane concentration of 50% by volume.

Estudo termogravimétrico do processo de sorção de metais pesados por resíduos sólidos orgânicos

Pollution of a hydrographic basin can cause alterations in physical, chemical and biological properties of water mass, committing its use for the human consumption and for other types of activities, depending on the contamination or pollution level. The conventional treatment methods for effluents containing heavy metals produce significant amounts of byproducts with recalcitrant characteristics; besides the techniques being onerous their reproducibility is low. The search for cheaper and definitive solutions led to the development of clean technologies, among these technologies the sorption process based on utilization of absorbent substances for these elements can be pointed out. This work has the objective of evaluating the sorption process of heavy metals by organic solid waste utilizing the thermogravimetric technique. The results obtained demonstrated that the profiles of the thermogravimetric curves of the organic solid waste presented significant modifications in the physical and chemical characteristics when submitted to the heavy metal sorption process.

Potentiometric and conductometric studies on the system acid-isopolytungstate and the formation of lanthanum tungstates

The stoichiometry of the polyanions formed by the action of nitric acid on sodium tungstate (≤ 0.01M) has been studied by means of electrometric techniques involving pH-potentiometric and conductometric titrations. The well defined inflections and breaks in the titration curves provide evidence for the existence of the polyanions, para-W12O41 10- and meta-W12O39 6- corresponding to the ratio of H+:WO 4 2- as 7:6 and 9:6 in the pH ranges 5.7-6.0 and 3.6-4.1, respectively. The interaction of lanthanum nitrate with sodium tungstate solutions, at specific pH levels 8.0, 5.9 and 4.0 was also studied by pH and conductometric titrations, in aqueous and alcoholic media, with each of the reagents alternatively used as titrant. The electrometric experiments provide definite evidence of the formation of normal-La2O3.3WO3, para-5La2O3.36WO3 and meta-La2O3.12WO3 tungstates in the vicinity of pH 6.3, 5.0 and 4.2, respectively. Analytical investigations on the precipitates formed confirm the results of the electrometric study.