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Is filter packing important in a small-scale vermifiltration process of urban wastewater?
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Resumo(s)
Nowadays, natural resources are under increasing stress which fosters wastewater reuse planning and emphasizes on the decentralized wastewater treatment. Vermifiltration has been described as a viable alternative to treat domestic and urban wastewater, but few studies have focused on the impact of different filter packings on vermifiltration performance. This study evaluates the effect of vermicompost and sawdust in a single-stage vermifilter (VF) for urban wastewater treatment. After an acclimation period of 45 days, urban wastewater from a combined sewage collection system was applied continuously for 24 h. Earthworm stock density was of 20 g L-1, HRT of 6 h, HLR of 0.89 m(3) m(-2) day(-1) and OLR of 7.38 g BOD5 day(-1). System performance was assessed by the removal efficiencies of BOD5, COD, TSS, NH4 (+), TN and TP, and fecal coliforms and helminth eggs elimination. Vermicompost (VE) and sawdust (SE) were tested, using an earthworm abundance of 20 g L-1. Treatment efficiencies were 91.3% for BOD5, 87.6% for COD, 98.4% for TSS and 76.5% for NH4 (+) in VE, and 90.5% for BOD5, 79.7% for COD, 98.4% for TSS and 63.4% for NH4 (+) in SE. Earthworms contributed to reduce NH4 (+) and TN removal and to increase NO3 (-) concentration. No treatment was able to eliminate fecal coliforms down to guidelines values for wastewater irrigation as helminth eggs were completely eliminated. Single-stage vermifiltration system using both filter packings is inconsistent and cannot meet EU guideline values for discharge in sensitive water bodies and WHO guidelines for irrigation with treated wastewater.
Descrição
Palavras-chave
Pathogen removal Sewage-treatment Sludge Performance Earthworms System
Contexto Educativo
Citação
Editora
Springer