RESUMO
Recalcitrant dyes found in textile wastewater represent a threat for sustainable textile production due to their resistance to conventional treatments. This study assessed an alternative co-composting system for the treatment of recalcitrant textile dyes where textile industrial sludge, sewage wastewater, or sewage sludge were used as microbial compost inocula. The biodegradation efficiency of bioreactor trials and compost quality of the co-composting system were assessed by visible spectrophotometry and by a phytotoxicity test. The co-composting system (dry weight (dw) basis) consisted of 200 g of restaurant organic residues + 200 g sewage sludge (or 100 mL sewage wastewater, or 200 g textile sludge) + 100 mL of a 10% dye solution (Reactive Red 195, or Synolon Brown, or Orange Remazol, or Yellow Synozol, or Reactive Orange 122, or Reactive Black 5). After 60 days of composting, all dyes were biodegraded according to spectrophotometric data, with efficiency varying from 97.2 to 99.9%. Inoculum efficiency ranking was textile sludge > sewage sludge > sewage wastewater. Regarding compost quality, a phytotoxicity study with lettuce showed no toxicity effect. Thus, co-composting can be a low-cost and efficient method for recalcitrant textile dye biodegradation and for managing textile sludge in terms of waste recycling, contributing to environmental sustainability.
Assuntos
Compostagem , Esgotos , Corantes , Solo , Têxteis , Águas ResiduáriasRESUMO
The aim of this work was to study the feasibility of textile sludge as a precursor to prepare catalysts for catalytic wet peroxide oxidation (CWPO) by chemical and thermal treatments. Textile sludge was characterized by physical-chemical and metal composition analyses. The chemical activation was evaluated using iron sulfate and the thermal treatment was carried out at 720⯰C in a vacuum pyrolysis reactor. Two catalysts with iron contents of 1.5% and 5.6% were selected. Process parameters influence on CWPO of phenol were evaluated and a maximum removal of phenol and TOC was observed at pH 3 and 60⯰C, using 3â¯gâ¯L-1 of the catalyst containing 5.6% of iron and 11.8â¯mmolâ¯L-1 of H2O2. Metal analysis indicated that the textile sludge is suitable to be employed as both iron catalyst and adsorbent. The catalysts characterization indicated a reasonable surface area with a well-developed microporosity and the presence of Hematite structures in the carbonaceous matrix. The degradation process achieved 98.2% of phenol conversion, 68.2% of mineralization and 2.11â¯mgâ¯L-1 of iron leaching in 150â¯min of reaction. The catalyst presented activity for up to 5 cycles of use, but with loss of efficiency.
RESUMO
RESUMO Neste trabalho avaliou-se o comportamento de um reator UASB em escala laboratorial (16 L) no tratamento de lodo biológico têxtil com produção de biogás, operando em diferentes temperaturas, 35 (mesofílica), 45 e 55ºC (termofílica), com tempo de detenção hidráulica (TDH) constante de 24 h. O reator UASB apresentou-se apto a tratar o lodo têxtil, sendo influenciado positivamente pelo incremento da temperatura, mostrando maiores remoções nas temperaturas termofílicas e com altas taxas de remoção de todos os parâmetros físico-químicos monitorados: demanda química de oxigênio (DQO) (97% em 45 e 55ºC), demanda bioquímica de oxigênio (DBO) (95% em 45ºC e 94% em 55ºC), fósforo total (P-total) (95% a 45 e 55ºC) e nitrogênio total (N-total) (94% a 45 e 55ºC). Quanto à produção de biogás e à concentração de metano, os maiores valores foram observados a 45ºC. Com base nos resultados alcançados, confirmam-se a tratabilidade do lodo têxtil e a produção de biogás em UASB, com melhor performance a 45ºC.
ABSTRACT The aim of this work was to evaluate the behavior of a laboratory-scale UASB reactor (16 L) in the treatment of textile biological sludge with biogas production, operating at different temperatures - 35 (mesophilic), 45 and 55ºC (thermophilic) -, with constant hydraulic retention time of 24 h. The UASB reactor was able to treat the textile sludge, being positively influenced by increasing temperature, with greater removals in thermophilic temperatures and high removal rates of all monitored physical and chemical parameters: chemical oxygen demand (COD) (97% at 45 and 55ºC), biochemical oxygen demand (BOD) (95% at 45ºC and 94% at 55ºC), total phosphorus (P-total) (95% at 45 and 55ºC) and total nitrogen (N-total) (94% at 45 and 55ºC). As for biogas production and methane concentration, the highest values were observed at 45ºC. Based on the results, textile sludge treatability and biogas production in UASB are confirmed, with best performance at 45ºC.
RESUMO
Sludge from the textile industry was used as a low-cost adsorbent to remove the dye Reactive Red 2 from an aqueous solution. Adsorbents were prepared through the thermal and chemical treatment of sludge originating from physical-chemical (PC) and biological (BIO) effluent treatment processes. The adsorbent characterization was carried out through physical-chemical analysis, X-ray fluorescence (XRF) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, pHPZC determination, Boehm titration method, Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy (SEM). Batch kinetic experiments and adsorption isotherm modeling were conducted under different pH and temperature conditions. The results for the kinetic studies indicate that the adsorption processes associated with these systems can be described by a pseudo-second-order model and for the equilibrium data the Langmuir model provided the best fit. The adsorption was strongly dependent on the pH but not on the temperature within the ranges studied. The maxima adsorption capacities were 159.3 mg g(-1) for the BIO adsorbent and 213.9 mg g(-1) for PC adsorbent at pH of 2 and 25 °C.
Assuntos
Naftalenossulfonatos/isolamento & purificação , Esgotos/química , Indústria Têxtil , Triazinas/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Poluição Química da Água/prevenção & controle , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Naftalenossulfonatos/química , Concentração Osmolar , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , Triazinas/química , Poluentes Químicos da Água/químicaRESUMO
A adsorção é uma das técnicas empregadas com sucesso para remoção efetiva da cor presente em efluentes têxteis. Com o objetivo de avaliar os diferentes parâmetros adsortivos, bem como determinar a eficiência de um adsorvente alternativo desenvolvido a partir de lodo residual têxtil na remoção de corantes, foram determinadas curvas de cinética de adsorção e isotermas. Por meio dos dados cinéticos e de equilíbrio obtidos, verificou-se que a 25ºC a adsorção foi favorável para todos os corantes, sendo esta a melhor condição para os corantes RO16 e RR2 na ausência de sais. Para o corante RR141, a adição de NaCl aumentou a capacidade de adsorção do adsorvente no equilíbrio e a adição de Na2SO4 favoreceu a adsorção para o corante RO16, ao contrário do que se observou para os outros dois corantes. A quantidade máxima de corante adsorvida por unidade de massa de adsorvente (q max) nas melhores condições adsortivas para os corantes RO16, RR2 e RR141 foi de 81,30, 53,48 e 78,74 mg.g-1, respectivamente.
The adsorption is one of the techniques that have been successfully used for effective removal of the dyes present in textile effluents. With the objective to evaluate the different adsorptive parameters, as well as determining the efficiency of one alternative adsorbent in the removal of dyes, kinetics and equilibrium data of adsorption were determined. By the kinetic data and of equilibrium, it was verified that the adsorption was favorable for all the dyes in 25ºC, being the best condition for the dye RO16 and RR2 in the total absence of salt. For the dye RR141, the addition of NaCl increased the adsorption capacity of adsorbent in the equilibrium and the addition of Na2SO4 favored the adsorption for the dye RO16, in contrast to what was observed for the two other dyes. The maximum quantity of dye adsorbed per unit mass of adsorbent (q max) in the best adsorptive conditions for the dyes RO16, RR2 and RR141 was of 81.30, 53.48 and 78.74 mg.g-1 respectively.