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

Marcelo Bruno,Roberto A. de Oliveira

doi:10.1590/s0100-69162013000400020

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 1.4g CODtotal (L d)-1. The 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 CH4 (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 post-treatment.

Highlights

IntroductionSeveral agricultural and agro-industrial processes use water, sometimes as raw material, for other maintenance processes or less noble uses as washing products and equipment, and/or to transport waste
Several agricultural and agro-industrial processes use water, sometimes as raw material, for other maintenance processes or less noble uses as washing products and equipment, and/or to transport waste.One of the agro-industrial processes that have stood out in water consumption and generation of solid and liquid waste are the husking and pulping coffee beans, known as wet processing, which originate the pulped coffee, the coffee with the mucilage removed and the peeled cherry
The changes in the composition of the affluent occurred due to variations in the collection time and may be related to changes in the amount of organic compounds present in coffee fruits and/or the amount of water used in washing or processed fruit mass, from start to the end of the season, as was observed by BRUNO & OLIVEIRA (2008)

Summary

Introduction

Several agricultural and agro-industrial processes use water, sometimes as raw material, for other maintenance processes or less noble uses as washing products and equipment, and/or to transport waste. One of the agro-industrial processes that have stood out in water consumption and generation of solid and liquid waste are the husking and pulping coffee beans, known as wet processing, which originate the pulped coffee, the coffee with the mucilage removed and the peeled cherry. Toward the increasingly demanding market, the search for quality is currently a major concern in the various productive sectors and, in particular coffee agribusiness. In regions that produces pulped and with mucilage removed coffee, the fate of these effluents has become a major environmental problem, with demand for simplified systems of waste and effluents treatment, with low cost of implantation and operation (BRUNO & OLIVEIRA, 2008). Because of the large consumption of water and introduction of organic matter and nutrients, they eventually acquire a high polluting power and if not properly treated and discharged into water bodies can cause the death of aquatic organisms due to high consumption of oxygen, contamination by toxic organic compounds, such as phenols, eutrophication and because of the high concentration of nitrogen

Methods

Results

Conclusion