BACKGROUND Textile wastewater is known for its polluting potential and toxicity. Biological, affordable treatments are especially desirable in developing countries to fulfill legal and ecological demands during its treatment. RESULTS The performance of an anaerobic structured‐bed reactor (AnSTBR) treating synthetic textile wastewater containing Direct Black 22 azo dye (DB22; 0.06 mmol L–1) and sulfate ions (200 mg L−1) was evaluated. The reactor hydraulic retention time (HRT) was 24 h and ethanol was used as the electron donor (1000 mgCOD L−1). The AnSTBR achieved an average decolorization efficiency of 68 ± 5%, chemical oxygen demand (COD) efficiency of 77.7 ± 9.2% and sulfate removal of 77.3 ± 5.2%. Toxicity tests showed lower toxicity of the treated effluent to Ceriodaphnia dubia. Despite that, the AnSTBR effluent was still highly toxic to mammalian cells. The metabarcoding technique of the 16S rRNA gene sequencing revealed a consistent community of sulfate‐reducing and azo‐degrading bacteria. CONCLUSION Metagenomic data revealed a promising development of the inoculum in the AnSTB structure. The AnSTB reactor configuration may be a promising alternative for DB22 dye removal from textile wastewater containing sulfate. © 2021 Society of Chemical Industry

This research aimed to compare the performance of two hybrid anaerobic immobilized biomass reactors (HAIB), in laboratory scale, processing vinasse from a sugar cane alcohol distillery. Reactor 1 received vinasse without pre-treatment. Reactor 2 processed coagulated vinasse using a calcium-based biopolymer as coagulant. The two reactors were built in acrylic, with a volume of 1,5 liters each. The recirculation flow rate was 3. The operation of the reactors was divided in two phases: first, lasting 69 days, came to an end characterized by a failure (collapse) presented by the reactor 2. The second phase, lasting 37 days, came to an end characterized by another collapse. The main control parameter in the monitoring of the reactors was the quantification of organic matter in terms of COD. During Phase I, the reactor 1 showed average removal efficiency of 82,9 ± 4,4 %, and the reactor 2 72,2 ± 18,1 %. The average organic loading rate (VOC) applied to reactor 1, during this phase, was 5,3 ± 1,3 kg DQO/m 3 d, and 5,3 ± 1,6 kg DQO/m 3 d for the reactor 2. The failure occurred in the reactor 2 was evidenced by the sharp decrease of removal efficiency, reaching 33.7%. During Phase II, the reactor 1 showed average removal efficiency of 77,5 ± 9,4 %, and the reactor 2 79,2 ± 9,7 %. The average VOC applied to reactor 1, during this phase, was 5,1 ± 2,4 kg DQO/m 3 d, and 5,0 ± 2,3 kg DQO/m 3 d for reactor 2. At the end of this phase, the reactor 1 showed a removal efficiency of 80.9%, and the reactor 2 65.8%. Has also been analyzed, alkalinity and methane (CH 4). During all the phases, the alkalinity of both reactors was above 1000 mg CaCO 3 /l, indicating stability in the reactors. The production of CH 4 was 0,0507 ± 0,0232 l CH 4 /h and 0,0326 ± 0,0838 l CH 4 /h in phases I and II, respectively. For the reactor 2, the production of CH 4 was 0,0307 ± 0,0137 l CH 4 /h e 0,08 ± 0,0297 l CH 4 /h for the phases I and II, respectively. Assays were performed in mechanical granules strength, analysis of scanning electron microscopy (SEM), Energy Dispersive Spectroscopy X-ray (EDS) and analysis of the microbial community, using molecular biology techniques. The tests of mechanical of granules strength indicate that the granules contained in the inoculum, reactors 1 and 2 were resistant to disintegration. The SEM and EDS analysis indicated the presence of calcium element with approximately 22% inoculum, 39% for reactor 1 and 50% for reactor 2, in the mass of the elements analyzed samples of granules. The microbial community analyzes indicated molecular similarity between the first and second reactor of 66,5 and 58% for Bacteria and Archaea domain, respectively. Thus, it is assumed that the difference between the biota of the reactors would not be contributing to the failure occurred in the reactor 2.

Liquid effluent generation in industrial plants is associated with production processes and employees. Based on the current legislation, these effluents must be subjected to treatment processes in order to be discharged at acceptable levels in receiving waterbodies. The company evaluated in the current study manufactures household and industrial tools and instruments; thus, the aim of the current study is to assess the activated sludge-based effluent treatment system adopted by it. Microscopic analyses of microfauna and biological floc structure, as well as sludge physicochemical and sedimentability analyses, were carried out. The sludge was classified as Pin-Point. Although Arcella sp. prevalence has given sludge a satisfactory clearance feature, the presence of Aspidisca sp. and Trachelophyllum sp. in it has indicated nitrification process and significantly old sludge, respectively. These features combined to low protozoan diversity and lack of micrometazoa have evidenced that sludge quality can be improved. Moreover, sludge overall presented poor settleability. Finally, improvements in the activated sludge system were suggested based on results observed in the current study.

RESUMO -No contexto em que há um crescimento da preocupação ambiental e um possível esgotamento do petróleo surge o interesse pela produção de alguns ácidos carboxílicos a partir de biomassa via fermentação, dentre eles o ácido propiônico. Ele é utilizado como antifúngico na alimentação humana e na conservação de grãos, aditivo em alimentos de origem animal, entre outros. O objetivo deste trabalho foi avaliar a influência da temperatura na batelada alimentada com células imobilizadas para a produção de ácido propiônico. Para isso, foi realizado o crescimento da bactéria do gênero Propionibacterium a 30ºC e pH 7 e esta foi imobilizada de forma passiva no bagaço para posterior utilização em fermentações conduzidas em biorreatores instrumentados com controle de temperatura a 30ºC e sem controle de temperatura. Além disso, a agitação foi mantida a 150 rpm e o pH em 7 com variação de +/-0,1. A fermentação onde o parâmetro temperatura foi controlado a 30ºC mostrou-se melhor, pois produziu cerca de 37 g/L de ácido propiônico em detrimento de 26 g/L produzidos no ensaio sem o controle, além de uma produtividade superior. Concluiu-se que foi possível a produção de ácido propiônico por rota biotecnológica e que o parâmetro temperatura é de suma importância na produção deste ácido utilizando células imobilizadas. INTRODUÇÃOOs ácidos orgânicos são de extrema importância nas indústrias química, de alimentos e farmacêutica. Os mais importantes dentre eles são os ácidos carboxílicos Uma das grandes aplicações de ácidos orgânicos é a sua utilização como intermediário na produção de plásticos biodegradáveis. Atualmente, muitos ácidos carboxílicos (incluindo os ácidos propiônico, butírico e acético) são produzidos, principalmente, por síntese química baseada no petróleo (YANG, 2008). Todavia, a preocupação com o esgotamento das reservas mundiais de matérias-primas fósseis estimulou a busca por fontes alternativas de produção de produtos petroquímicos e, neste contexto, está inserido o ácido propiônico.Recentemente, este ácido tem chamado a atenção por ser um importante bloco de construção químico de três átomos de carbonos. Dentre as suas mais variadas aplicações, destacam-se seu papel como conservante na indústria de alimentos, aromatizante na indústria de cosméticos, além de aplicações farmacêuticas e na produção de plásticos e herbicidas (SUWANNAKHAM et al., 2006).

This study investigated the influence of a previous sugarcane vinasse coagulation, by using a calcium-based biopolymer, on anaerobic treatment in a lab-scale reactor. Two anaerobic reactors (R1 and R2) were operated for 155 days. R1 was fed only with raw sugarcane vinasse and R2 was fed with pretreated effluent. The operation was divided into three stages: E1 (inoculation and adaptation); E2; and E3. The major difference between E2 and E3 was the fact that R2 failed at the end of E2. Thus, R2 was recovered by applying a low organic loading rate (OLR) of raw vinasse for 29 days. In E2 and E3, for both reactors, pH, alkalinity, COD (influent and effluent samples), and methane production were monitored. During E1, an OLR of 2.0 kgCOD. m-3.d-1  1 was applied, and R1 and R2 sludges showed good adaptation to the wastewater in this condition. Then, the OLR was progressively increased to 7.0 kgCOD.m-3.d-1 in both systems. The average COD removal efficiencies were 82.9 ± 4.4% and 72.2 ± 18.1% for R1 and R2, respectively. R2, operated with pretreated vinasse, showed a decrease in the COD removal and methane production, which could be caused by the biopolymer presence. The average COD removal efficiencies in E3 were 77.5 ± 9.4% and 79.2 ± 9.7% for R1 and R2, respectively. After 155 days of operation, a decrease in the COD removal and methane production was identified again in R2, indicating a new failure. The quality of sludge granules from the inoculum and also from the granules developed at the end of R1 and R2 operation was analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). These analyses indicated a rise in the rugosity of R1 and R2 granules, possibly due to the deposition of sedimentable compounds present in both raw and pretreated vinasse. The EDS analyses indicated a high presence of calcium in R2 granules, indicating that this compound acted in the reduction of mass transfer between organic load from vinasse and the granules’ microbiota.

The presence of natural organic matter (NOM) in water does not present direct risk to the human body or to the environment. However, its presence along with other pollutants can lead to countless issues and damage human health and the environment. The hydrodynamic cavitation (HC) phenomenon started being used in the early 21st century as a process capable of treating supply-water and wastewater based on pollutant and pathogen degradation. Process effectiveness increases when it is combined to chemical agents, creating an advanced oxidation process (AOP). Although several studies have presented broaden applications for the HC process, its use for NOM removal from supply-water was not yet assessed; therefore, it remains a gap in scientific knowledge. The aim of the current study is to assess HC potential in NOM removal. In order to do so, the experiments were carried out in bench scale hydrodynamic cavitation system operated at batch model within 15-min duration period-of-time. In addition, decantation experiments (24-h period-of-time) were performed in order to check HC influence on molecules found in reaction medium after the exposure of NOM to the phenomenon. NOM was produced by a synthetic humic acid (HA) matrix at fixed concentration of 100 ppm. In total, 16 experiments were carried out; each experiment was featured by the following pair: pH (2.6, 3.0, 3.5 and 5.5) and hydrogen peroxide (0, 1, 5 and 30 mL). The best removal efficiencies (34%-36%) were observed in the most acidic pH ranges (2.6-3.0) at H2O2 concentration of 15mL. Results have presented high NOM removal efficiency (approximately 90%) after decantation at the most acidic pH ranges, as well. It can be explained by the fact that hydrodynamic cavitation in acid solution can break molecular structures suspended in the liquid medium, which favors decantation. Based on the present study, hydrodynamic cavitation with hydrogen peroxide addition can remove NOM from water; moreover, pH control is an essential factor for process development.

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