Reuse of textile wastewater treated by moving bed biofilm reactor coupled with membrane bioreactor

This is the peer reviewed version of the following article: [ Yang, X, López-Grimau, V, Vilaseca, M, et al. Reuse of textile wastewater treated by moving bed biofilm reactor coupled with membrane bioreactor. Coloration Technol. 2021; 137: 484– 492. https://doi.org/10.1111/cote.12543], which has been published in final form at https://doi.org/10.1111/cote.12543. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.A laboratory-scale pilot plant of moving bed biofilm reactor coupled with membrane bioreactor (MBBR-MBR) was studied with regard to wastewater treatment in the textile industry, and the reuse feasibility of treated water was investigated. The pilot plant comprised two connected parts: an aerobic tank filled with carriers and a submerged membrane tank. The MBBR-MBR system reduced the hydraulic retention time to 1 day, which is very promising compared with conventional biological treatment in the textile industry. The removal efficiency of chemical oxygen demand reached 93%, which is almost the maximum for a biological process treating this type of wastewater, as well as the colour removal performance, which achieved 85%. Additionally, 99% of total suspended solids were removed due to filtration. Furthermore, new dyeing processes reusing the treated water were performed. The quality of the new dyed fabrics with treated water was compared with reference fabrics. Colour differences between new dyed fabrics and reference fabrics were found to be within the general requirement of the textile industry (¿ECMC(2:1) < 1). The reuse of treated water in new dyeing processes is beneficial both for the industry and for the environment, because the textile sector is an intensive water consumer during both the dyeing and finishing processes.This study is co-funded by ACCIÓ (Generalitat de Catalunya) within the REGIREU Project (COMRDI16-1-0062).Peer ReviewedPostprint (author's final draft

Hydrolysis and methanogenesis in UASB-AnMBR treating municipal wastewater under psychrophilic conditions: Importance of reactor configuration and inoculum

Three upflow anaerobic sludge blanket (UASB) pilot scale reactors with different configurations and inocula: flocculent biomass (F-UASB), flocculent biomass and membrane solids separation (F-AnMBR) and granular biomass and membrane solids separation (G-AnMBR) were operated to compare start-up, solids hydrolysis and effluent quality. The parallel operation of UASBs with these different configurations at low temperatures (9.7 ± 2.4°C) and the low COD content (sCOD 54.1 ± 10.3 mg/L and pCOD 84.1 ± 48.5 mg/L), was novel and not previously reported. A quick start-up was observed for the three reactors and could be attributed to the previous acclimation of the seed sludge to the settled wastewater and to low temperatures. The results obtained for the first 45 days of operation showed that solids management was critical to reach a high effluent quality. Overall, the F-AnMBR showed higher rates of hydrolysis per solid removed (38%) among the three different UASB configurations tested. Flocculent biomass promoted slightly higher hydrolysis than granular biomass. The effluent quality obtained in the F-AnMBR was 38.0 ± 5.9 mg pCOD/L, 0.4 ± 0.9 mg sCOD/L, 9.9 ± 1.3 mg BOD5/L and <1 mg TSS/L. The microbial diversity of the biomass was also assessed. Bacteroidales and Clostridiales were the major bacterial fermenter orders detected and a relative high abundance of syntrophic bacteria was also detected. Additionally, an elevated abundance of sulfate reducing bacteria (SRB) was also identified and was attributed to the low COD/SO42– ratio of the wastewater (0.5). Also, the coexistence of acetoclastic and hydrogenotrophic methanogenesis was suggested. Overall this study demonstrates the suitability of UASB reactors coupled with membrane can achieve a high effluent quality when treating municipal wastewater under psychrophilic temperatures with F-AnMBR promoting slightly higher hydrolysis rate

Anaerobic Membrane Bioreactor (AnMBR) for the Treatment of Cheese Whey for the Potential Recovery of Water and Energy

A single-stage Anaerobic Membrane Bioreactor (AnMBR) for the treatment of cheese whey and its co-digestion with cattle slurry was investigated with the aim of potentially recovering water and energy from the wastewater. A 9 L reactor coupled to an ultrafiltration flat sheet membrane module in an external configuration was employed. This configuration enabled the proper separation of solids from permeate. Cheese whey was stored at room temperature and its chemical oxygen demand (COD) varied between 51 and 80 g/L. The reactor was operated at an average hydraulic retention time (HRT) of 15 days and at an organic loading rate (OLR) of 1.2–8.4 kg COD/(m3·day). During operation a COD removal average of 91% ± 7% was achieved. The biogas production ranged from 0.2 to 0.9 m3 biogas/kg COD removed and its methane content was 51–73%. From these results, a potential energy recovery of 2.4 kWh/kg COD removed was calculated. Microbial community analysis showed that bacteria belonging to the orders Bacteroidales and Clostridiales became the most prevalent. The bioreactor was dominated by acetotrophic methanogenesis. The co-digestion of cheese whey with cow manure (3:1) did not decrease NaOH consumption for pH control. Water reuse for cleaning purposes is possible if permeate pH is maintained at 6. Prior to the scaling-up of the system, a pilot scale test would be necessary to optimise membrane performance. The use of AnMBR technology at a real scale would be appropriate since it is a compact technology which permits both energy and potential water recovery after permeate post-treatment, thus constituting a further step towards the establishment of a broader a circular economy approach