Methane Production From Cassava Starch Wastewater in Packed-Bed Reactor and Continuous Flow

Abstract

The aim of this study was to evaluate the behavior of an anaerobic reactor of packed-bed and continuous flow, in relation to the biogas and methane production and the removal of organic load, from the wastewater of cassava starch extraction. For this purpose, were tested, in a reactor with a useful volume of 2.82 L and support mean of polypropylene filled with polyethylene foam, the organic loading rate (OLR) of 2.5, 5.0, 8.0 and 10.0 g L -1 d -1 . It was evaluated the removal of COD, the pH, the VA/TA ratio, the biogas and the methane production. It was concluded from this study that it is possible to produce biogas with methane percentages higher than 80% (maximum) and remove the organic load more than 90% under the tested conditions. In relation to stability, the reactor can be considered stable for the parameters, pH, the relationship between volatile acidity and total alkalinity and organic load removal. The best results in relation to the average volumetric biogas production (0.174 and 0.311 L g COD -1 ) were obtained for the higher organic loading rate (of 8 and 10 g L -1 d -1 , respectively) and the observed tendency is that with the increase of the organic loading rate, the specific biogas production will increase as well as the specific production of methane.

Cassava Wastewater Treatment in Fixed-Bed Reactors: Organic Matter Removal and Biogas Production

“…Fuess et al (2017) suggest that the biogas release to the liquid medium can be favored by adoption of the structured fixed bed, since this configuration provide increase in the empty spaces and improvement in the reactor hydrodynamic characteristics. The horizontal reactors used in this study, as well as those operated by Kunzler et al (2013) and Palma et al (2018) presented biogas production performance lower than that obtained by Araujo et al (2018) in an upflow fixed bed reactor. This reactor configuration provides more efficient mixing, improving mass transfer rates between substrate and microorganisms, promoting the release of trapped gas bubbles in the liquid and preventing the particulate matter sedimentation (Ward et al, 2008).…”

“…The biogas volume was measured by a liquid displacement system filled with an acidified saline solution composed by sulfuric acid (3% v/v) and sodium chloride (25% m/v), indicated to maintain all the biogas constituents (Fernandes Junior, 1995). The methane volume was estimated with basis in reactors fed with cassava wastewater and operated in similar conditions (Kuczman et al, 2014;Araujo et al, 2018;Mari, 2018).…”

“…To ensure the representative estimative of the methane content in the biogas, we researched works with methane content at biogas in the OLR applied range. Therefore, we adopted three average values: 70% for the assays A1 to A5 (OLR from 1.7 to 4.7 g.L −1 .d −1 ) (Kuczman et al, 2013;Araujo et al, 2018;Mari, 2018); 73% for the assays A6 to A9 (OLR from 5.6 to 7.2 g.L −1 .d −1 ) (Araujo et al, 2018;Mari, 2018) and 69% for the assays A10 to A13 (OLR from 10 to 15.1 g.L −1 .d −1 ) (Araujo et al, 2018;Mari, 2018). Methane content in biogas was estimated at 70 ± 2%, with average methane production rate of 0.5 ± 0.2 and 0.4 ± 0.1 LCH 4 .L −1 .d −1 for R1 and R2, respectively.…”

“…From assay A11 there was a recovery of biogas production, which can indicate high resilience of the reactor, possibly due to biomass immobilization. Araujo et al (2018) evaluated the methane production in an upflow anaerobic fixed bed reactor from cassava starch wastewater and observed that the biogas production increase (0.8 to 7.56 L.d −1 ) was proportional to OLR increase (2.5 to 10 g.L −1 .d −1 ), however, the methane proportion in biogas decreased from 76.8 to 66%, respectively. The increase in organic and hydraulic loads can cause disturbances in microbial community structure of the reactor.…”

Decreasing of Environmental Loads in Tapioca Industry Through Utilization of Biogas Digester Effluent for Fertigation During Vegetables Production

“…With the presence of organic nitrogen compounds, the effluent composition is expected to have contribution in increasing soil pH value (from acid to neutral) due to bicarbonate alkalinity. Bicarbonate that can be produced from the anaerobic decomposition of organic nitrogen compounds derived from wastewater, is the main source of buffer capacity in the neutral pH [18].…”