Ecotoxicological response surface analysis of salt and pH in textile effluent on Bacillus subtilis and Lactuca sativa.

Textile effluents, although their composition can vary considerably, typically contain high levels of dissolved salts and exhibit wide variations in pH. Ecotoxicological studies regarding the effects of these parameters, however, have been limited owing to the need for sensitive and easy-to-handle bioindicators that require low amounts of sampling, are cost-effective, time-efficient, and ethically endorsed. This kind of study, additionally, demands robust multi-factorial statistical designs that can accurately characterize the individual and combined relationship between variables. In this research, Response Surface Methodology (RSM) was used to calculate the individual and interaction effects of NaCl concentration and pH value of a Simulated Textile Effluent (STE) on the development rate (DR) of the bioindicators: Bacillus subtilis bacteria and Lactuca sativa lettuce. The results demonstrated that the bioindicators were sensitive to both NaCl and pH factors, where the relative sensitivity relationship was B. subtilis > L. sativa. The quadratic equations generated in the experiments indicated that increased concentrations of 50-250 mg L-1 of NaCl caused a perturbance of 1.40%-34.40% on the DR of B. subtilis and 0.50%-12.30% on L. sativa. The pH factor at values of 3-11 caused an alteration of 27.00%-64.78% on the DR of the B. subtilis and 51.37%-37.37% on the L. sativa. These findings suggest that the selected bioindicators could serve as effective tools to assess the ecotoxicological effects of textile effluents on different ecological systems, and the RSM was an excellent tool to consider the ecotoxicological effects of the parameters and to describe the behavior of the results. In conclusion, the NaCl and pH factors may be responsible for disrupting different ecosystems, causing imbalances in their biodiversity and biomass. Before discharge or reuse, it is suggested to remove salts and neutralize pH from textile effluents and, mostly, develop novel, eco-friendlier textile processing techniques.

Challenges and emerging perspectives of an international SARS-CoV-2 epidemiological surveillance in wastewater.

SARS-CoV-2 is a new type of coronavirus capable to infect humans and cause the severe acute respiratory syndrome COVID-19, a disease that has been causing huge impacts across the Earth. COVID-19 patients, including mild, pre-symptomatic and asymptomatic cases, were often seen to contain infectious fragments of SARS-CoV-2 in feces and urine samples. Therefore, studies to detect the new coronavirus in wastewater, which collect and concentrate human excreta, have been extremely useful as a viral tracking tool in communities. This type of monitoring, in addition to serve as a non-invasive early warning of COVID-19 outbreaks, would provide better predictions about the SARS-CoV-2 spread and strongly contribute to maintenance the global health. Although current methods to detect viruses in wastewater, based on molecular RT-PCR and RT-qPCR techniques, were considered as reliable and provided accurate qualitative and quantitative results, they have been facing considerable challenges concerning the SARS-CoV-2 surveillance. In this review, the methods used to detect the SARS-CoV-2 in wastewater and the challenges to implement an international viral monitoring network were described. The article also addressed the emerging perspectives associated with the SARS-CoV-2 epidemiological surveillance in this environment and the importance of a worldwide collaboration to generate and disseminate the detection results.

Evaluating the potential of electrolysed water for the disinfection of citrus fruit in packinghouses.

BACKGROUND: The largest and most profitable market for citrus is the production of fresh fruit. Xanthomonas citri subsp. citri is a Gram-negative plant pathogen and the etiological agent of citrus canker, one of the major threats to citrus production worldwide. In the early stages of infection, X. citri can attach to plant surfaces by means of biofilms. Biofilm is considered an essential virulence factor, which helps tissue colonization in plants. Thus, sanitization of citrus fruit is mandatory in packinghouses before any logistic operation as packing and shipment to the market. The aim of this study was to evaluate electrolysed water (EW) as a sanitizer for the disinfection of citrus fruit in packinghouses. RESULTS: Using a protocol to monitor cell respiration we show that EW, obtained after 8 and 9 min of electrolysis, sufficed to kill X. citri when applied at a concentration of 500 µL mL-1 . Furthermore, microscopy analysis, combined with time-response growth curves, confirmed that EW affects the bacterial cytoplasmatic membrane and it leads to cell death in the first few minutes of contact. Pathogenicity tests using limes to simulate packinghouse treatment showed that EW, produced with 9 min of electrolysis, was a very effective sanitizer capable of eliminating X. citri from contaminated fruit. CONCLUSION: It was possible to conclude that EW is significantly effective as sodium hypochlorite (NaClO) at 200 ppm. Therefore, EW could be an alternative for citrus sanitization in packinghouses. © 2020 Society of Chemical Industry.

Electrochemical oxidation of landfill leachate in a flow reactor: optimization using response surface methodology.

Response surface methodology based on Box-Behnken (BBD) design was successfully applied to the optimization in the operating conditions of the electrochemical oxidation of sanitary landfill leachate aimed for making this method feasible for scale up. Landfill leachate was treated in continuous batch-recirculation system, where a dimensional stable anode (DSA(©)) coated with Ti/TiO2 and RuO2 film oxide were used. The effects of three variables, current density (milliampere per square centimeter), time of treatment (minutes), and supporting electrolyte dosage (moles per liter) upon the total organic carbon removal were evaluated. Optimized conditions were obtained for the highest desirability at 244.11 mA/cm(2), 41.78 min, and 0.07 mol/L of NaCl and 242.84 mA/cm(2), 37.07 min, and 0.07 mol/L of Na2SO4. Under the optimal conditions, 54.99% of chemical oxygen demand (COD) and 71.07 ammonia nitrogen (NH3-N) removal was achieved with NaCl and 45.50 of COD and 62.13 NH3-N with Na2SO4. A new kinetic model predicted obtained from the relation between BBD and the kinetic model was suggested.

Toxicological evaluation of vegetable oils and biodiesel in soil during the biodegradation process

Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida. are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula (Eruca sativa and lettuce (Lactuca sativa. to analyze the germination of seeds in contaminated soil samples. The toxicological experiment was conducted with four different periods of biodegradation in soil: zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. On the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.

Toxicological evaluation of vegetable oils and biodiesel in soil during the biodegradation process.

Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida) are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula (Eruca sativa) and lettuce (Lactuca sativa) to analyze the germination of seeds in contaminated soil samples. The toxicological experiment was conducted with four different periods of biodegradation in soil: zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. On the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.

A thin layer electrochemical cell for disinfection of water contaminated with Staphylococcus aureus / Uma célula eletroquímica de camada delgada para desinfecção de água contaminada com Staphylococcus aureus

A thin layer electrochemical cell was tested and developed for disinfection treatment of water artificially contaminated with Staphylococcus aureus. Electrolysis was performed with a low-voltage DC power source applying current densities of 75 mA cm-2(3 A) or 25 mA cm-2 (1 A). A dimensionally stable anode (DSA) of titanium coated with an oxide layer of 70 percentTiO2 plus 30 percentRuO2 (w/w) and a 3 mm from a stainless-steel 304 cathode was used in the thin layer cell. The experiments were carried out using a bacteria suspension containing 0.08 M sodium sulphate with chloridefree to determine the bacterial inactivation efficacy of the thin layer cell without the generation of chlorine. The chlorine can promote the formation of trihalomethanes (THM) that are carcinogenic. S. aureus inactivation increased with electrolysis time and lower flow rate. The flow rates used were 200 or 500 L h-1. At 500 L h-1 and 75 mA cm -2 the inactivation after 60 min was about three logs of decreasing for colony forming units by mL. However, 100 percent inactivation for S. aureus was observed at 5.6 V and 75 mA cm-2 after 30 min. Thus, significant disinfection levels can be achieved without adding oxidant substances or generation of chlorine in the water.

Uma célula eletroquímica de camada delgada foi utilizada e desenvolvida para a desinfecção de água contaminada artificialmente com Staphylococcus aureus. A eletrólise foi executada com uma fonte de corrente direta utilizando 75 mA cm-2 (3 A) ou 25 mA cm-2 (1 A). Um anodo dimensionalmente estável (DSA) de titânio revestido com uma camada do óxido de 70 por centoTiO2 e 30 por centoRuO2 (w/w) e distanciado por 3 milímetros de um catodo de aço inoxidável 304 foi utilizado para gerar uma camada delgada de suspensão bacteriana passando pela célula de camada delgada. As suspensões utilizadas eram feitas apenas com Na2SO4 0,08 M e livre de íons cloretos de forma a inativar as células bacterianas no tratamento eletroquímico sem a geração de cloro, este pode promover a formação dos trialometanos (THM). As taxas de fluxo em recirculação foram 200 ou 500 L h-1. A inativação do S. aureus aumentou com o tempo de eletrólise e a uma taxa de fluxo menor. Assim, a inativação de 100 por cento para o S. aureus foi observada após 30 min a 5,6 V e 75 mA cm-2. Em 500 L h-1 e 75 mA cm-2 a inativação decresceu em três logs de unidades formadoras de colônias por mL após 60 min. O tratamento eletroquímico utilizando uma camada delgada promove a desinfecção completa de S. aureus sem a necessidade de adicionar substâncias oxidantes ou a geração de cloro.

A thin layer electrochemical cell for disinfection of water contaminated with Staphylococcus aureus.

A thin layer electrochemical cell was tested and developed for disinfection treatment of water artificially contaminated with Staphylococcus aureus. Electrolysis was performed with a low-voltage DC power source applying current densities of 75 mA cm(-2) (3 A) or 25 mA cm(-2) (1 A). A dimensionally stable anode (DSA) of titanium coated with an oxide layer of 70%TiO2 plus 30%RuO2 (w/w) and a 3 mm from a stainless-steel 304 cathode was used in the thin layer cell. The experiments were carried out using a bacteria suspension containing 0.08 M sodium sulphate with chloride-free to determine the bacterial inactivation efficacy of the thin layer cell without the generation of chlorine. The chlorine can promote the formation of trihalomethanes (THM) that are carcinogenic. S. aureus inactivation increased with electrolysis time and lower flow rate. The flow rates used were 200 or 500 L h(-1). At 500 L h(-1) and 75 mA cm(-2) the inactivation after 60 min was about three logs of decreasing for colony forming units by mL. However, 100% inactivation for S. aureus was observed at 5.6 V and 75 mA cm(-2) after 30 min. Thus, significant disinfection levels can be achieved without adding oxidant substances or generation of chlorine in the water.

Effects of the electrolytic treatment on Bacillus subtilis

Processos convencionais de desinfecção de águas podem gerar compostos tóxicos. Esse é o caso dos trialometanos formados na reação do cloro com compostos orgânicos presentes na água. O tratamento eletrolítico pode ser um substituto à cloração com vantagem de não requer a adição de nenhum composto na água. O efeito do tratamento eletrolítico, utilizando eletrodos de carbono, na viabilidade de Bacillus subtilis foi testado para se determinar o mecanismo de morte. Através de microscopia eletrônica, foi possível evidenciar que a morte do microrganismo se deu pela lise celular, provavelmente provocada pela eletroporação irreversível da membrana celular.

Effects of the electrolytic treatment on Bacillus subtilis

Conventional processes of water disinfection can generate toxic composites. It is the case of the trihalomethanes (carcinogenic) formed in the contact of chlorine with organic substances present in the water. The electrolytic treatment can be a substitute for the chlorination process without the need for addition of chemical substances to the process. The effect of the electrolytic treatment using carbon cathode on the viability of the microorganism Bacillus subtilis was tested to determine the death process. By means of electronic microscopy, it was observed that the main cause of the microorganism's death was the cellular lysis due to the electroporation in the cell membrane.

Processos convencionais de desinfecção de águas podem gerar compostos tóxicos. Esse é o caso dos trialometanos formados na reação do cloro com compostos orgânicos presentes na água. O tratamento eletrolítico pode ser um substituto à cloração com vantagem de não requer a adição de nenhum composto na água. O efeito do tratamento eletrolítico, utilizando eletrodos de carbono, na viabilidade de Bacillus subtilis foi testado para se determinar o mecanismo de morte. Através de microscopia eletrônica, foi possível evidenciar que a morte do microrganismo se deu pela lise celular, provavelmente provocada pela eletroporação irreversível da membrana celular.

Alterações morfológicas em Bacillus subtilis pela eletrólise / Morfological alteration in Bacillus subtilis by electrolisys

O tratamento de águas de abastecimento é indispensável à saúde pública. Tradicionalmente, o tratamento de água implica adição de substâncias químicas que podem gerar compostos tóxicos afetando a saúde daqueles que a utilizam. A cloração, por exemplo, promove a formação de compostos tóxicos como os trialometanos, de reconhecido efeito carcinogênico, além de apresentarem outros efeitos toxicológicos. O tratamento eletrolítico pode ser uma alternativa na desinfecção de águas de abastecimento e residuárias. Além das vantagens para a saúde pública, o tratamento eletrolítico, por não requerer a adiçaõ de nenhuma substância ao processo, pode ser utilizado em indústrias de alta tecnologia que necessitem de águas extremamente puras em seus processos. O objetivo deste estudo foi observar o efeito do tratamento eletrolítitco com cátodo de carbono sobre a morfologia do Bacillus subtilis. Suspensões de B. subtilis em tampão fosfato 0,2M em pH 7,2 livre de cloreto foram eletrolisadas com cátodo de carbono verificado e ânodo de platina recorbeto membrana de diálise. A corrente aplicada ao processo foi de 0,60A DC por 30 min. As suspensões eletrolisadas foram coradas pelo método de Gram e observadas ao microscópio óptico; observadas ao microscópio eletrônico de varredura após sua preparação. Os resutados permitem concluir que a eletrólise promove alterações na estrutura da parede do B. subtilis além de extravasamento de material celular

Comparação da eficiência dos eletrodos de carbono, titânio e TiRuO2 na desinfecção de águas / Comparision of eficiency of the carbon, titanium and TiRuO2 electrodes in water desifection

A desinfecção de águas de abastecimento é de vital importância para a saúde pública. Porém processos convencionais de desinfecção, por requererem a dição de substâncias à água, podem gerar compostos tóxicos como é o caso dos trialometanos formados quando o cloro entra em contato com substãncias orgãnicas presente na água. O tratamento eletrolítico pode ser um substituto para o processo de cloração com a vantagem de não requerer a adição de nenhuma susbstância ao processo. O tratamento eletrolítico é facilmente automatizável, versátil, requer pouco espaço para sua implantação e tem baixo custo operacional.O presente trabalho visou comparar o efeito do tratamento eletrolítico com eletrodos de carbono, titânio e titânio recoberto por óxido de titânio e óxido de rutênio(TiRuO2) na viabilidade do Bacillus subtilis. Suspensões de B. subtilis foram determinados: o número de células viáveis, o pH e a temperatura. Os resultados permitiram concluir que o eletrodo de carbono reduz a viabilidade do bacilo em 99,999 por cento em 30 min de eletrólise, ao passo que os eletrodos de titânio e TiRuO2 não possibilitaram uma redução significativa até 45 min depois do tratamento

Tratamento de efluente de uma indústria química através do processo eletrolítico visando a diminuiçäo da toxidade monitorada pelo bioindicador saccharomyces cerevisiae / Eletrolytic treatment of an effluente of a chemical industry for monitoring toxicity by Saccharomyces cerevisiae

O tratamento do efluente de uma indústria química produtora de antioxidante e antiozonante para borracha foi realizado através da eletrólise com o intuito de diminuir a toxidade dos resíduos persistentes e recalcitrantes presentes no efluente. A influência de diversos fatores foi estudada, utilizando-se eletrodos de aço. Os resultados obtidos mostraram a diminuiçäo da toxidade do efluente bruto indicaram que, com o aumento do tempo de eletrólise, o efluente tornou-se menos tóxico ou mais biodegradável. Para as substâncias antioxonantes, Flexzone 3P e Flexzone 7P, houve um aumento da viabilidade celular após 10 minutos de eletrólise. Para as substâncias antioxidantes, Aminox e Naugard Q, a eletrólise apresentou pouca influência na toxidade, pois essas substâncias näo se mostraram tóxicas ao Saccharomyces cerevisiae. Dessa forma, pode-se concluir que o processo eletrolítico permitiu uma diminuiçäo da concentraçäo de substâncias persistentes no efluente tornando-o mais biocompatível ao meio ambiente

Aplicaçäo do processo eletrolítico como forma de tratamento de efluente de uma indústria produtora de antiozonante para borracha / Eletrolytic treatment in the effluent of a rubber antizonant chemical industry

O processo eletrolítico foi aplicado no tratamento de efluente de uma indústria produtora de antiozonante para borracha de forma a melhorar as condições quanto à biodegradabilidade de resíduos persistentes. A influência de diversos fatores foi estudada utilizando-se eletrodos de aço e TiRuO2. Os resultados obtidos mostraram transformações moleculares, levando à diminuiçäo de toxidade e cor. espectros de UV-visível de efluente bruto eletrolisado, com eletrodo de TiRuO2, mostraram tranformações mais intensas que o efluente que o efluente eletrolisado com eletrodo de aço. A eletrólise produziu também transformaçäo nas moléculas de n-fenil-n-isopropil-p-fenilenodiamina (nome comercial, FLEXZONE 3P), n-fenil-n'-1,3-dimetilbutil-p-fenilenodiamina (nome comercial, FLEXZONE 7P). Pode-se concluir que o tratamento eletrolítico se mostrou viável para transformar as moléculas persistentes e recalcitrantes presentes no efluente de uma indústria química produtora de antiozonante para borracha