Performance of UASB reactors in two stages followed by post-treatment with activated sludge in wastewater batch of wet-processed coffee

Abstract

ABSTRACT:In this study it was evaluated the efficiency of the treatment of wet-processed coffee wastewater in upflow anaerobic sludge blanket (UASB) reactors in two stages, in bench scale, followed by post-treatment with activated sludge in batch. The first UASB reactor was submitted to an hydraulic retention time (HRT) of 6.2 d and organic loading rates (OLR) of 2.3 and 4.5g CODtotal (L d) -1 , and the second UASB reactor to HRT of 3.1 d with OLR of 0.4 and 1.4gThe average values of the affluent CODtotal increased from 13,891 to 27,926mg L -1 and the average efficiencies of removal of the CODtotal decreased from 95 to 91%, respectively, in the UASB reactors in two stages. The volumetric methane production increased from 0.274 to 0.323L CH 4 (L reactor d) -1 with increment in the OLR. The average concentrations of total phenols in the affluent were of 48 and 163mg L -1 , and the removal efficiencies in the UASB reactors in two stages of 92 and 90%, respectively, and increased to 97% with post-treatment. The average values of the removal efficiencies of total nitrogen and phosphorus were of 57 to 80% and 44 to 60%, respectively, in the UASB reactors in two stages and increased to 91 and 84% with the posttreatment.KEYWORDS: anaerobic digestion, methane, nitrogen, phosphorus, phenols. -1 , e as eficiências médias de remoção nos reatores UASB em dois estágios, de 92 e 90%, respectivamente, e aumentaram para 97% com o pós-tratamento. As eficiências médias de remoção de nitrogênio e fósforo total variaram, respectivamente, de 57 a 80% e de 44 a 60% nos reatores UASB em dois estágios e aumentaram para 91 e 84% com a inclusão do pós-tratamento. PALAVRAS-CHAVE: digestão anaeróbia, fenóis, fósforo, metano, nitrogênio. DESEMPENHO DE REATORES UASB EM DOIS ESTÁGIOS SEGUIDOS DE PÓS-TRATAMENTO COM LODOS ATIVADOS EM BATELADA DE ÁGUAS RESIDUÁRIAS DO BENEFICIAMENTO DE CAFÉ POR

Removal of phenols and methane production with coffee processing wastewater supplemented with phosphorous

“…The TN influent ranged between 201 and 446 mg/L and was variable and superior in tests 3 and 4 with the SSP addition. Such results are similar to those reported by Bruno and Oliveira (2013) with 332 mg/L of TN and 13891 mg/L of COD. Approximated values of TN between both substrates might be a consequence of the collection of the fruits on the same university farm in Jaboticabal, São Paulo.…”

“…TF was variable and not proportional to COD, as it reached values above 500 mg/L. Such concentrations were approximately 4.5 times higher than those reported by Oliveira and Bruno (2013) (105 mg/L TF) through a CPW simulation process for COD of 16,000 mg/L.…”

“…CaSO 4 Á2H 2 O) was the phosphorous source for the obtaining of a COD:N:P relation of minimal 350:5:1 (Speece 1996). A minimal proportion of COD:SSP necessary was 350:4.6 with maximal deficiency of phosphorous in CPW between 60 and 70 % (Bruno and Oliveira 2013;Rossmann et al 2013), 15-16 % SSP solubilization in water and a 18 % P 2 O 5 content in the product (corresponding to 50.8 % of phosphorous). The SSP was manually macerated and mixed in excess with the CPW at concentrations of 2 g/L for test 3 and 4 g/L for test 4, respectively (Table 1).…”

“…HAR (Oliveira and Bruno 2013) and FBR (Fia et al 2012) achieved COD removals of 97 and 52 % of total phenols (TF) with biomass brackets; hence, a bioenergy productivity between 1.4 and 1.7 L CH 4 /L.d. HAR included three 1.2-L serial reactors filled with sludge blanket, bamboo and coconut fiber, respectively, which operated at 90 h hydraulic retention time (HRT) and organic load rate (OLR) between 8.9 and 25 g COD/L.d.…”

“…The configuration of the two-stage UASB reactor with SBR was tested by Bruno and Oliveira (2013). The authors achieved removals of 95 % for COD and 84 % for TF with HRT of 329.5 h (223.2 h for UASB reactors and 106.3 h for SBR) and OLRs between 2.3 and 4.3 g COD/L.d.…”