Biomass of Bovine Origin in the Removal of Basic contaminants in a Sequential Batch Reactor

Abstract

The purpose of the present investigation was to evaluate the potential of cattle manure as biomass in suspension in sequential discontinuous reactors (SBR) at different hydraulic retention times, to improve the removal of basic contaminants from domestic wastewater. The SBR reactors for the experiment were built in triplicate with an operating capacity of 720 L. The bovine manure to be used as biomass in suspension was determined (average ± SD) the dry biomass (72.3 ± 6.2%), humidity (27.7 ± 6.2%), pH (7.8 ± 1.3) and volatile matter (0.15 ± 0.05 kg mv / kg manure). The microbial sludge (10 kg of manure) was prepared in the SBR with domestic residual water, stabilizing in approximately 21 days, subsequently experiments with hydraulic retention times (TRH) were performed at 15, 20 and 25 hours, contrasting with the residual water raw. The SBR was operated with an active mud volume of 0.29 m3, an exchange volume of 0.43 m3 (59.7%), settling time of 1 h, reaction time of 5 h, SSVLM of 1600 mg/L, TMRC of 6 days and Y of 0.21 kg / cell / lb. The experimental data on water quality (influent and effluent) were statistically analyzed with non-parametric tests, as they did not meet normality and homoscedasticity postulates with the Kruskal-Wallis test and the Mann-Whitney test of medians with a P-value <0.05, indicating statistically significant differences between the medians with a level of 95.0% confidence of the evaluated treatments. The most efficient treatment was HRT 20 h, with (median ± SD) Turbidity 9.2 ± 0.84 UNT, Color with 286.2 ± 34.53 UC, pH 6.15 ± 0.77, water temperature of 29.9 ± 1.57 ° C, Electrical conductivity (EC) of 1103.35 ± 102.1 µS cm-1, dissolved oxygen (DO) with 4.2 ± 0.42 mg/L, chemical oxygen demand (COD) with 35.6 ± 2.98 mg/L and total suspended solids (TSS) of 26.35 ± 1.20 mg/L, For the 15-hour HRT, removal efficiencies for COD of 75.8% were obtained, in the 20-hour HRT 92.4% (COD); while the 25-hour HRT presented efficiencies of 64.5% (COD). This treatment alternative meets the criteria for discharge to receptor bodies established by NOM-001-SEMARNAT-1996. SBRs with vaccine biomass can be used with confidence for small discontinuous flows, since they do not use sophisticated equipment, do not require secondary harmful reagents and their only requirement is electrical energy.