Luis Alcides Schiavo Miranda

Biogas production from co-digestion of organic fraction of municipal solid waste and fruit and vegetable waste

The anaerobic co-digestion of organic fraction of municipal solid waste (OFMSW) and fruit and vegetable waste (FVW) was evaluated in terms of biogas and methane yield, volatile solids (VS) removal rate and stability of the process. The batch experiment was conducted in mesophilic conditions (35°C), with four different OFMSW/FVW ratios (VS basis) of 1/0, 1/1, 1/3, and 0/1. The methane yield from the co-digestion was higher than the mono-digestion for OFMSW and FVW. The optimal mixing ratio of OFMSW/FVW was found to be 1/3. The average cumulative biogas and methane yield in this condition was 493.8NmL/gVS and 396.6NmL/gVS, respectively, and the VS removal rate was 54.6%. Compared with the mono-digestion of OFMSW and FVW, the average increase in methane yield was 141% and 43.8%, respectively.

A compact remediation system for the treatment of groundwater contaminated with BTEX and TPH.

ABSTRACT Gas stations constitute important point sources of soil and groundwater pollution. The leaking of hydrocarbons into the soil is a significant environment issue due to the wide-ranging occurrence of leaks and the high levels and toxicity of pollutants involved in the contamination of groundwater for human use. This study introduces a compact system developed to treat groundwater contaminated with benzene, toluene, ethyl benzene, and xylenes (BTEX) and total petroleum hydrocarbon (TPH) leaked from gas station tanks. The system comprises three units: (1) suction and volatilization of volatile organic compounds (VOCs), (2) aeration tank (to remove volatile organic substances), and (3) an adsorption packed-bed filter (activated carbon (AC) and rice husk ash, 50% each, to remove TPH). Contaminated groundwater was characterized in a pilot study and in the field. Levels of BTEX and of TPH decreased by 96% with an 8-h retention time. The results obtained show that the remediation system is highly efficient and yielded water that met the discharge standards defined in the Brazilian legislation, that is, maximum benzene, toluene, and xylene levels of 5, 170, and 300 μg/L, respectively.

Avaliação da viabilidade de utilização de colifagos como indicadores de poluição fecal: suas relações com parâmetros físicos e químicos e indicadores bacterianos

Coliform bacteria, currently used as fecal indicator, does not ensure the absence of other pathogenic microorganisms in water, mainly enteric viruses. The objective of this study was to evaluate the viability of using coliphages as viral indicators in the effluent from Wastewater Treatment Plants (WWTP) due to the fact that Coliphages determination involves a simplified methodology. The seasonal pattern of coliphages was measured in the final effluent of a domestic WWTP, which occurred in higher values, mainly during dry seasons periods. This behavior was similar with the described by the authors in relation to enteric viruses in water. Significant relationship was not found among coliphages and coliforms, as well as with the physical and chemical parameters analyzed. The need for joint monitoring of viruses and bacteria is emphasized, in order to ensure the proper quality of treated water.