Aldre Jorge Morais Barros

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.

Dessorção de nitrogênio amoniacal de lixiviado de aterro sanitário em torres de recheio

Sanitary landfill leachates present high concentrations of carbonaceous and nitrogenous materials. The crucial point is that carbonaceous materials are of difficult biodegradation, what compromises the performance of biological treatment processes, while nitrogenous materials, such as ammonia nitrogen, probably preclude the use of biological treatments. Therefore, the aim of this work was to study the desorption process of ammonia nitrogen from sanitary landfill leachate in filling towers. Desorption was carried out in filling towers of 35 L capacity. The leachate was collected from a sanitary landfill located in Joao Pessoa, Paraiba State, Brazil. Desorption efficiency for the pH values ​​adopted in four treatments was 93% minimum and 95.5% maximum, with aeration mean time ranging from 3 to 6 hours. The limiting factors of ammonia nitrogen desorption from sanitary landfill leachates in filling towers are associated with the use of alkalizer species for pH correction, and electricity costs for aeration.

Influence of temperature on the anaerobic stabilization of organic solid residues

This study was aimed at determining the effect of temperature on the stabilization of organic solid waste conjugated with sewage sludge in anaerobic batch reactors (ABR), and to estimate the efficiency of the process in producing biogas and methane. The substrate contained 36.2 g L-1 of total solids comprising residues from fruits and vegetables enriched with anaerobic sludge from sanitary sewage (4:1, w/w). The reactors were of 1.15 L capacity and were operated at 25.5, 40 and 50°C (ABR1, ABR2 and ABR3, respectively) for 160 days. The efficiencies of transformation of total volatile solids in ABR1, ABR2 and ABR3 were, respectively, 43.2, 34.2 and 32%, and the transformation of chemical oxygen demand showed a similar tendency with efficiencies of 39.5, 33.6 and 16.6%, respectively. The mean volumes of biogas accumulated by ABR1, ABR2 and ABR3 were 28.85, 21.24 and 20.54 L, respectively, while the respective mean volumes of methane were 9.04, 7.11 and 1.11 L. The results demonstrate that the activity of methane-producing microorganisms was inhibited at higher process temperatures. It is concluded that anaerobic digestion at ambient temperature represents an economical and environmentally viable strategy for the disposal of municipal solid wastes. Key words: Plant residues, anaerobic digestion, biofuel, methane

Digestão Anaeróbia de Resíduos Vegetais com Baixa Concentração

In Brazil, the solid wastes of plant and animal origin , account quantitatively for 55 % of municipal solid waste. Anaerobic digestion is an important alternative for the treatment of waste with high concentrations of putrescible organic materials , considering incorporating low operating costs and produce clean energy source . The experimental apparatus of this work consisted of an anaerobic baffled reactor and unit shredding solid waste and ancillary equipment . The waste mass was composed of ten different types of wastes collected in central supply , transported to the laboratory and subjected to grinding and screening . The efficiency of biostabilization the mass of COD was 54.1 %, providing methane production rate of 0.13 LCH4 . g -1COD . Considering the significant mass of carbonaceous material on the substrate, the production rate of methane was relatively low , compared to the time monitoring fifty days.