COD, TSS, nutrients and coliforms removals in UASB reactors in two stages treating swine wastewater

Abstract

SUMMARY:The performance of two upflow anaerobic sludge blanket (UASB) reactors was evaluated in pilot scale (908 and 188 L), installed in series (R1 and R2), fed with swine wastewater with TSS around 5 and 13 g L -1 . The UASB reactors were submitted to HDT of 36 and 18 h with VOL of 5.5 to 34.4 g COD (L d) -1 in the R1 and HDT of 7.5 e 3.7 h with VOL from 5.1 to 45.2 g COD (L d) -1 in the R2. The average removal efficiencies of COD ranged from 55 to 85% in the R1 and from 43 to 57% in the R2, resulting in values from 82 to 93% in the UASB reactors in two stage. Methane concentrations in the biogas were 69 to 74% with specific production from 0.05 to 0.27 L CH 4 (g removed COD) -1 in the R1 and of 0.10 to 0.12 L CH 4 (g removed COD) -1 in the R2. The average removal efficiencies were 61 to 75% for total P, 39 to 69% for KN, 82 to 93% for org N and 20 to 94% for Fe, Zn, Cu and Mn. The am N concentration were not reduced indicating the need to post-treatment for effluent disposal into water bodies. There were reductions of total coliforms from 99.8123 to 99.9989% and of thermotolerant coliforms from 99.9725 to 99.9999%. The conditions imposed to the UASB reactors in two stage provided high conversions of removed COD into methane (up to 77%) and reductions of organic an inorganic pollution loads from swine wastewater.KEYWORDS: volumetric organic load, methane, N and P removal, metal removal, suspended solids. REMOÇÕES DE DQO, SÓLIDOS, NUTRIENTES E COLIFORMES EM REATORES UASB EM DOIS ESTÁGIOS TRATANDO ÁGUAS RESIDUÁRIAS DE SUINOCULTURARESUMO: Foi avaliado o desempenho de dois reatores anaeróbios de fluxo ascendente com manta de lodo (UASB) em escala-piloto (908 e 188 L), instalados em série (R1 e R2), para o tratamento de águas residuárias de suinocultura com concentrações médias de SST em torno de 5 e 13 g L -1 . Os TDH foram de 36 e 18 h com COV de 5,5 a 34,4 g DQO (L d) -1 no R1 e TDH de 7,5 e 3,7 h com COV de 5,1 a 45,2 g DQO (L d) -1 no R2. As eficiências médias de remoção de DQO variaram de 55 a 85% no R1 e de 43 a 57% no R2, resultando valores de 82 a 93% nos reatores UASB em dois estágios. As concentrações de metano no biogás foram de 69 a 74%, com produções de 0,05 a 0,27 L CH 4 (g DQOremovida) -1 no R1 e de 0,10 a 0,12 L CH 4 (g DQOremovida) -1 no R2. Os valores médios de eficiência de remoção de Ptotal foram de 61 a 75%; de NK de 39 a 69%; de Norg. de 82 a 93%, e de Fe, Zn, Cu e Mn de 20 a 94%. As concentrações de N-am. não foram reduzidas, indicando a necessidade de pós-tratamento para disposição do efluente em corpos d'água. Houve redução de coliformes totais de 99,8123 a 99,9989%, e de coliformes termotolerantes de 99,9725 a 99,9999%. As condições impostas aos reatores UASB em dois estágios propiciaram reduções acentuadas da carga poluidora orgânica e inorgânica das águas residuárias de suinocultura, com conversão de até 77% da DQO removida em metano. PALAVRAS-CHAVE:carga orgânica volumétrica, metano, remoção de N e P, remoção de metais, sólidos suspensos.

Anaerobic co-digestion of vegetable waste and swine wastewater in high-rate horizontal reactors with fixed bed

“…Lower thermotolerant coliforms removals up to 96% occurred in SW treatment in UASB reactor and anaerobic filter with OLR of 23 g COD (L d) À1 and HDT of 20.5 h (Pereira-Ramirez et al, 2004). Similar removals of 99.8% and 99.9% of thermotolerant coliforms at OLR of 9.7 and 13.2 g COD total (L d) À1 , and HDT of 54 and 44 h were reported by Sylvestre et al (2014) and Ramires and Oliveira (2014) in SW treated in systems with UASB reactors, anaerobic filter, biological filter and decanter. The anaerobic-aerobic treatment system used by Sylvestre et al (2014), higher HDT (13 d) in-series HARFB and co-digestion with VW still were not enough to achieve removal of thermotolerant coliforms above 99.9%.…”

“…Aiming to improve the quality of the effluent to avoid a possible contamination by pathogenic microorganisms, the microbiological quality of affluents and effluents was analyzed (Table 7). High concentrations of total and thermotolerant coliforms of 2.4 Â 10 8 to 1.2 Â 10 10 MPN (100 ml) À1 and of 2.1 Â 10 8 to 6.6 Â 10 9 MPN (100 ml) À1 , respectively, were reported in SW by Pereira-Ramirez et al (2004), Sylvestre et al (2014) and Ramires and Oliveira (2014). Similar counts up to 2.1 Â 10 10 and 1.7 Â 10 9 MPN (100 ml) À1 of total and thermotolerant coliforms, respectively, occurred in the test 1 (100% SW) (Table 7), confirming the high level of microbiological contamination indicators in the affluent.…”

Biogas Yield and Productiveness of Swine Manure for Different Reactor Configurations

“…Experimental phase organic load rates (OLRs), volatile solid (VS) composition, hydraulic retention time (HRT), and dilution ratio of swine manure (SM) with water (W) applied for the assays with the upflow anaerobic sludge blanket reactor (UASB). In many studies on the production of biogas from SM in a UASB reactor, the strategy used for OLR control is effluent dilution (Ramires et al, 2014). The planning used in phase II of the present study made it possible to observe an important change in the characteristic of the sludge blanket, from a granular to a flocculent characteristic.…”

Reduction of Soluble Organic Carbon and Removal of Total Phosphorus and Metals From Swine Wastewater by Electrocoagulation

“…Among the methods of biological swine wastewater treatment, the upflow anaerobic sludge blanket (UASB) is used for treating wastes with high soluble organic loads and works at low hydraulic retention times (Zhao et al, 2008). However, this system still does not generate effluents that reach discharge standards according to Brazilian and international regulations (Foresti et al, 2006;Ramires and Oliveira, 2014).…”