Desempenho de reatores anaeróbios de leito fixo no tratamento de águas residuárias da lavagem e descascamento/despolpa dos frutos do cafeeiro / Performance of the anaerobic fixed-bed reactors in the treatment of wastewater from the washing and pulping/husking the cherries of the coffee shrub

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Three anaerobic fixed-bed reactors with upflow and containing immobilized biomass were operationally evaluated for the treatment of wastewater from the coffee cherries processing (WCP). Because the performance of those reactors are related to the supportive medium providing adherence and growth to the biofilm, the following materials were studied: blast furnace scum, polyurethane foam and crushed stone #2 with porosity 53, 95 and 48%, respectively. The reactors were made with PVC and total volume for 139.5L. They were operated under environmental temperature varying from 6.4 to 32.9C, with average value 17.2C. Their operations consisted of increasing the organic load, that was quantified in terms of COD (1000, 2500 and 5000 mg L-1) flowing to reactors, by keeping a stable hydraulic residence time (HRT) around 1.3 days. The reactors were monitored, by collecting both the affluent and effluent samples of the reactors, and quantifying the variables: COD, BOD, phenolic compounds, TS, TVS, TSS, VSS, total nitrogen, phosphorus, sodium, potassium, pH, alkalinity, volatile acids and electric conductivity. At the end of the evaluated conditions, the WCP samples were collected along the height of the reactors for kinetic study, as well as those of the formed biofilm for microscopic observations. For an affluent COD value around 5000 mg L-1, the reactor infilled with foam showed an average removal efficiency of 80 and 83% for the total and filtered COD respectively. This fact is due to its higher porosity, that provided higher retention and fixation of the biomass, that when quantified under the TVS form was 1,301 mg g-1 foam. By the other hand, the reactor infilled with scum generated effluents with lower concentrations of phenolic compounds that were statistically different (P <0.05) from those obtained in the other reactors. The increase in the COD flowing to the reactors also made possible the development and growth of the adhered microbial biofilm that showed wide variety of species, as been registered some morphologies similar to bacilli, curved bacilli, coccus, filaments, Methanosaeta sp. and Methanosarcina sp., this last one with lower frequency. Based on the results, it is concluded that the reactors showed satisfactory performance, which make them a viable alternative to be used in the treatment of WCP, as emphasizing the polyurethane foam as supportive material.

ASSUNTO(S)

filtro anaeróbio poluição café controle Águas residuais processamento coffee processing biological treatment engenharia de agua e solo tratamento biológico husking pollution control anaerobic filter despolpamento wastewater

ACESSO AO ARTIGO

Documentos Relacionados