Different electrolytic treatments for food sanitation and conservation simulating a wash process at the packinghouse.

Microorganisms are predominantly responsible for food deterioration, necessitating the sanitization and removal of these entities from food surfaces. The packinghouse employs free chlorine in the sanitization process; however, free chlorine's propensity to react with organic matter, forming potentially toxic compounds, has led to its restriction or outright prohibition in several European countries. Therefore, this study aims to assess various washing methods, emulating packinghouse conditions, utilizing diverse forms of electrolyzed water to impede microbial proliferation and significantly enhance the food's shelf life. The subject of investigation was cherry tomatoes. The findings revealed that electrolyzed water containing NaCl exhibited superior efficacy compared to electrolysis with Na2SO4. Both forms of electrolyzed water demonstrated noteworthy effectiveness in inhibiting microorganisms, resulting in a reduction of 2.0 Log CFU mL-1 for bacteria and 1.5 Log CFU mL-1 for fungi. The electrolyzed water also exhibited a comparable capability to free chlorine in removing fecal coliforms from the tomato surfaces. Notably, both electrolyzed water treatments extended the shelf life of cherry tomatoes by at least three days, accompanied by minimal or negligible residues of free chlorine. Consequently, the electrolyzed water formulations proposed in this study present themselves as promising alternatives to traditional packinghouse sanitizers. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05882-1.

Riscos associados à presença do SARS-CoV-2 em esgotos e possíveis abordagens para limitar sua propagação através de matrizes aquáticas / Risks associated with the presence of SARS-CoV-2 in sewage and possible approaches to limit its spread through aquatic matrices

Introdução: O SARS-CoV-2 é um novo tipo de coronavírus capaz de infectar humanos e causar a Coronavirus Disease (COVID-19), enfermidade que tem causado enormes impactos no Brasil e no mundo. A doença, devido às suas altas taxas de disseminação e letalidade, foi declarada pandêmica pela Organização Mundial da Saúde no primeiro semestre de 2020. Vários estudos têm frequentemente indicado a detecção de fragmentos de RNA do SARS-CoV-2 em amostras de redes de esgoto, estações de tratamento e águas naturais. A presença do SARS-CoV-2 nesses ambientes tem levantado a possibilidade de transmissão pelo contato com águas contaminadas e aerossóis gerados durante seus fluxos ou tratamentos. Objetivo: Descrever relatos de detecção do novo coronavírus em amostras obtidas em redes de esgotos, em lodos residuais de plantas de tratamento e em corpos d'água naturais, e apresentar a viabilidade desse vírus quando inoculado artificialmente nesses ambientes. Método: Revisão integrativa de literatura fundamentada em artigos científicos escritos em inglês ou português, indexados nas bases de dados do Web of Science, Scopus, PubMed, ScienceDirect, Google Scholar e MedRxiv. Resultados: Foi possível destacar os riscos que o SARS-CoV-2 proporciona às populações de humanos e de animais selvagens quando presente nas águas residuais, estratégias cabíveis de serem utilizadas para limitar a propagação desse patógeno nas matrizes aquáticas, e a importância da implementação de sistemas de monitoramento epidemiológico nesses locais. Conclusões: A fim de reduzir os riscos de surtos emergentes e reemergentes da COVID-19 por meio de matrizes aquosas, abordagens preventivas em relação à presença do SARS-CoV-2 nesses ambientes têm sido fortemente recomendadas.

Introduction: SARS-CoV-2 is a new type of  coronavirus capable of infecting humans and cause the Coronavirus Disease (COVID-19), an illness that has causing enormous impacts in Brazil and worldwide. The disease, due to its high-level dissemination and lethality rates, was declared pandemic by the World Health Organization in the first half of 2020. Several studies have frequently indicated the detection of SARS-CoV-2 RNA fragments in samples from sewage networks, treatment plants and natural waters. The presence of SARS-CoV-2 in those environments has raised the possibility of transmission through the contact with contaminated waters and aerosols generated during their flow or treatment. Objective: Describe detection reports of the new coronavius in samples obtained from sewage networks, from waste sludges of treatment plants and from natural water bodies, and present the viability of this virus when artificially inoculated in those environments. Method: Integrative literature review based on scientific articles written in English or Portuguese, indexed in the Web of Science, Scopus, PubMed, ScienceDirect, Google Scholar and MedRxiv databases. Results: It was possible to highlight the risks that the SARS-CoV-2 poses to human and wildlife populations when present in wastewater, appropriate strategies to be used to limit the spread of this pathogen in aquatic matrices, and the importance of implementing epidemiological monitoring systems in those places. Conclusions: In order to reduce the risks of emerging and re- emerging outbreaks of COVID-19 through aqueous matrices, precautionary approaches regarding the presence of SARS-CoV-2 in those environments have been strongly recommended.

Antibacterial action and target mechanisms of zinc oxide nanoparticles against bacterial pathogens.

Zinc oxide nanoparticles (ZnO NPs) are one of the most widely used nanoparticulate materials due to their antimicrobial properties, but their main mechanism of action (MOA) has not been fully elucidated. This study characterized ZnO NPs by using X-ray diffraction, FT-IR spectroscopy and scanning electron microscopy. Antimicrobial activity of ZnO NPs against the clinically relevant bacteria Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and the Gram-positive model Bacillus subtilis was evaluated by performing resazurin microtiter assay (REMA) after exposure to the ZnO NPs at concentrations ranging from 0.2 to 1.4 mM. Sensitivity was observed at 0.6 mM for the Gram-negative and 1.0 mM for the Gram-positive cells. Fluorescence microscopy was used to examine the interference of ZnO NPs on the membrane and the cell division apparatus of B. subtilis (amy::pspac-ftsZ-gfpmut1) expressing FtsZ-GFP. The results showed that ZnO NPs did not interfere with the assembly of the divisional Z-ring. However, 70% of the cells exhibited damage in the cytoplasmic membrane after 15 min of exposure to the ZnO NPs. Electrostatic forces, production of Zn2+ ions and the generation of reactive oxygen species were described as possible pathways of the bactericidal action of ZnO. Therefore, understanding the bactericidal MOA of ZnO NPs can potentially help in the construction of predictive models to fight bacterial resistance.

Green Manure Species for Phytoremediation of Soil With Tebuthiuron and Vinasse.

Tebuthiuron is often used to control weed growth in sugarcane cultures. This herbicide is highly toxic and can persist in soil for up to 2 years according to its degradation half-life. Hence, its residual effect is highly hazardous for the environment and local habitants via leaching, surface runoff. Screening out of species of green manure as potential phytoremediators for tebuthiuron in soil, with and with no vinasse, accordingly is the scientific point of this study. Green manure species selected for the trial in greenhouse were jack bean [Canavalia ensiformis (L.) DC.], pigeon pea [Cajanus cajan (L. Millsp.)], velvet bean [Mucuna pruriens (L.) DC.)], and millet [Pennisetum glaucum (L.) R.Br.], and Crotalaria juncea L. as bioindicator of this herbicide. The determination/quantification of height, stem diameter, and number of leaves in all plants were monitored, as well as other morphological traits for drafting any inference on biomass production. Moreover, ecotoxicity bioassays were performed from soil samples at the beginning and at the end of the experiment. Results showed preliminary evidence of effective phytoremediation capacity by M. pruriens and P. glaucum in soils with tebuthiuron, as the growth of C. juncea was sustained. Both Gompertz approach and principal component analysis predicted that these green manure species could grow healthier and for longer periods in soils containing tebuthiuron and vinasse and, thus, reduce physiological anomalies due to ecotoxicity. The implications of this study may aid in the implementation of cost-effective strategies targeting decontamination of tebuthiuron in sugarcane crops with vinasse application in fertigation.

The addition of a quaternary group in biopolymeric material increases the adsorptive capacity of Acid Blue 25 textile dye.

The quaternization of chitosan molecules creates materials with high adsorptive capacity towards textile dyes, which renders them capable of rapidly removing such dyes from a solution. In this study, a novel material was synthesized in bead form to adsorb the Acid Blue 25 textile dye. The adsorption isotherms, kinetics, and thermodynamics of this new material were investigated. The beads were further characterized by FT-IR and SEM studies, as well as their rheological behavior. Bioassays with Daphnia similis analyzed the toxicity of the dye before and after treatments. The Freundlich isotherm model fitted to all the adsorption data in a pH range from 2.50 to 8.50. Kinetic studies showed that adsorption was ruled by an intraparticle diffusion process and reached equilibrium in 270 min, as 39.527 µg mg-1 of dye was sorbed to the beads. Thermodynamic studies showed that adsorption was a spontaneous and endothermic process. Thermodynamics also confirmed that the adsorption was proportionally influenced by higher temperatures. The FT-IR spectroscopy identified the adsorbate/adsorbent binding sites, thus confirming the occurrence of chemisorption. Post-treatment bioassays found a significant decrease in toxicity, obtaining just 10% of D. similis mortality after adsorption treatments. Therefore, the synthesized beads from this research can potentially be applied to the treatment of textile effluents.

Comparative study of phytotoxicity and genotoxicity of soil contaminated with biodiesel, diesel fuel and petroleum.

The worldwide spillage of fossil fuels causes an ever-increasing environmental concern due to their resistance to biodegradation and toxicity. The diesel fuel is one of the derivative forms of petroleum that is widely used in the world. Its composition has many aromatic compounds and long hydrocarbons chains, both persistent and hazardous, thus requiring complex microbial dynamics to achieve full biodegradation. At this point, biodiesel has advantages because it is produced from renewable sources. It also has a relatively fast biodegradation. Biodiesel formulation chemically varies according to the raw material used for its production. While vegetable oils tend to have homogeneous proportions of linoleic and oleic fatty acids, animal fats have an heterogeneous distribution of stearic, palmitic and oleic fatty acids. As some studies have already detected the toxic potential of biodiesel from vegetable oil, this study sought information on the phytotoxic and genotoxic potential of animal fat-based biodiesel and compare it with fossil fuel as diesel fuel and crude petroleum. The impacts on the microbial activity of soils contaminated with biodiesel, diesel fuel and crude petroleum were performed by the dehydrogenase activity. Phytotoxicity tests were performed with Eruca sativa seeds and genotoxicity bioassays with Allium cepa seeds. The results showed a rapid assimilation of biodiesel by the autochthonous soil microorganisms. Soil contaminated with either diesel or crude petroleum inhibited the root and hypocotyl elongation of E. sativa. Overall, petroleum contaminated soils showed higher genotoxic potential. Biodiesel from animal fat was rapidly assimilated by soil microorganisms and did not present significant phytotoxic or genotoxic potential, but significantly reduced the mitotic index of A. cepa roots. Our results showed that biodiesel from animal fat have rapid biodegradability. Biodiesel also led to less impacts during seed development and lower genotoxic potential when compared to crude petroleum and diesel fuel. In addition, biodiesel from animal fat does not present the same toxicity demonstrated by biodiesel from soybean-based biodiesel described in current literature.

Fluorinated waste and firefighting activities: biodegradation of hydrocarbons from petrochemical refinery soil co-contaminated with halogenated foams.

Perfluorinated compounds, including fluorotelomers, are important constituents of firefighting foams to extinguish fuel fires in the petrochemical industry, airports, and at fire-training sites. In this study, we monitored the biodegradation process in a co-contamination scenario with monoaromatic hydrocarbons commonly found in fuels (benzene, toluene) and fluorotelomers. The CO2 production rates were evaluated by a factorial design taking into account the effect of seasonality at in situ natural attenuation processes. Headspace analysis by gas chromatography with a thermal conductivity detector (GC-TCD) was applied to detect CO2 production, whereas monoaromatics were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). According to our results, seasonality had a detectable effect during summer, yielding different CO2 production rates. Higher temperatures increased CO2 production rate, while higher concentrations of fluorotelomer inhibited the biodegradation process. On average, benzene and toluene were depleted 17.5 days earlier in control assays without fluorotelomers. Toluene removal efficiency was also notably higher than benzene. The noticeable decrease in degradation rates of monoaromatics was caused by perfluorinated compounds that are possibly linked to metabolic inhibition mechanisms. Fluorotelomer diminished catabolism in all of our batch cultures. In addition to this, an alternative production of by-products could be detected. Thus, we propose that transient components of the benzene and toluene degradation may be differentially formed, causing the benzene, toluene, and perfluorinated co-contaminations to go through switched metabolic stages under the presence of fluoride in a contamination scenario.

Electrochemically assisted photocatalysis: Highly efficient treatment using thermal titanium oxides doped and non-doped electrodes for water disinfection.

Electrochemically assisted photocatalysis (by electronic drainage) is a highly promising method for disinfection of water. In this research, the efficiency of photolytic oxidation using UV-A radiation and electrochemically assisted photocatalysis (with electric potential of 1.5 V) was studied by using electrodes prepared by thermal treatment and doped with silver, for inactivation of Escherichia coli and Staphylococcus aureus. The Chick-Watson microorganism inactivation model was applied and the electrical energy consumption of the process was calculated. It was observed no significant inactivation of microorganisms when UV-A light or electric potential were applied separately. However, the electrochemically assisted photocatalytic process, with Ag-doped electrode completely inactivated the microbial population after 10 (E. coli) and 60 min (S. aureus). The best performing non-doped electrodes achieved 52.74% (E. coli) and 44.09% (S. aureus) inactivation rates after 60 min. Thus, electrochemically assisted photocatalytic activity was not only effective for the inactivation of microorganisms, but also notably low on electrical energy consumption during the treatment due to small current and low electric potential applied.

The effects of fluoride based fire-fighting foams on soil microbiota activity and plant growth during natural attenuation of perfluorinated compounds.

The use of fluoride based foams increases the effectiveness of fire-fighting operations, but they are also accompanied by major drawbacks regarding environmental safety of perfluorinated compounds (PFCs). The main concern with PFCs release is due to their well-known persistence and bioaccumulative potential, as they have been detected in many environmental samples. There is a significant knowledge gap on PFC toxicity to plants, even though such data could be useful towards bioremediation procedures. It is consensus that a realistic assessment of fire-fighting foam toxicity should cover as many test organisms as possible, however, few studies combine the performance of ecotoxicological tests with a detailed study of microbial communities in soil contaminated with firefighting foams. Our research evaluated the effects of natural attenuation of PFCs on the development of arugula and lettuce seeds. The effects of variable PFCs amounts were also observed in soil microbiota using the 2,6 dichlorophenol-indophenol redox dye as microbial metabolism indicator. We aimed to determine whether aqueous film forming foams toxicity increased or decreased over time in a simulated contamination scenario. We argued that the long-term biotransformation of fire-fighting foams should be taken in to account when evaluating toxicity, focusing on a time-based monitoring analysis, since potentially toxic intermediates may be formed though biodegradation. The phyto-toxicity of PFCs to lettuce and arugula was high, increasing as a function of the concentration and decreasing as a function of exposure time to the environment. However, very specific concentrations throughout biodegradation result in the formation of non-inhibiting intermediates. Therefore, variable biodegradation-dependent germination rates may be misleading on non-time-based monitoring approaches. Also, the low phyto-toxicity after 240days does not exclude the potential for PFC bioaccumulation in plants. We also proposed that the colorimetric data modelling could also establish a novel toxicity parameter to evaluate the release impacts to soil and biota. The combined assays allowed the monitoring of PFCs during long-term exposition to plants as well as their immediate effects on the same soil microbiota.

Metabolical shifts towards alternative BTEX biodegradation intermediates induced by perfluorinated compounds in firefighting foams.

The type and concentration of perfluorinated compounds (PFCs) can induce different types of enzymes and promote alternate patterns of BTEX transformation. However, it is not known how the presence of active fluorocarbon-degrading microbial populations affects the transformation of BTEX. In addition to chemical analysis at the molecular level, our research approached the aqueous film forming fire-fighting foams (AFFF) and BTEX co-contamination at a large-scale with respirometers to quantify the total microbial metabolism of soil via CO2 output levels. The intended outcome of this research was to obtain and characterize shifts in BTEX degradation at a set realistic environmental condition while measuring byproducts and CO2 production. Both methodologies complimentarily provided an in-depth knowledge of the environmental behavior of fire-fighting foams. The biodegradation was monitored using headspace sampling and two types of gas chromatography: thermal conductivity detector and flame ionization detector. Headspace samples were periodically withdrawn for BTEX biodegradation and CO2 production analysis. Our research suggests the discovery of an altered metabolic pathway in aromatic hydrocarbons biodegradation that is directly affected by fluorinated substances. The fluorinated compounds affected the BTEX biodegradation kinetics, as PFCs may contribute to a shift in styrene and catechol concentrations in co-contamination scenarios. A faster production of styrene and catechol was detected. Catechol is also rapidly consumed, thus undergoing further metabolic stages earlier under the presence of PFCs. The release of AFFF compounds not only changes byproducts output but also drastically disturbs the soil microbiota according to the highly variable CO2 yields. Therefore, we observed a high sensitivity of microbial consortia due to PFCs in the AFFF formulation, therefore shifting their BTEX degradation routes in terms of intermediate products concentration.

A high-performance doped photocatalysts for inactivation of total coliforms in superficial waters using different sources of radiation.

Photocatalytic water treatment has a currently elevated electricity demand and maintenance costs, but the photocatalytic water treatment may also assist in overcoming the limitations and drawbacks of conventional water treatment processes. Among the Advanced Oxidation Processes, heterogeneous photocatalysis is one of the most widely and efficiently used processes to degrade and/or remove a wide range of polluting compounds. The goal of this work was to find out a highly efficient photocatalytic disinfection process in superficial water with different doped photocatalysts and using three sources of radiation: mercury vapor lamp, solar simulator and UV-A LED. Three doped photocatalysts were prepared, SiZnO, NSiZnO and FNSiZnO. The inactivation efficiency of each synthesized photocatalysts was compared to a TiO2 P25 (Degussa(®)) 0.5 g L(-1) control. Photolysis inactivation efficiency was 85% with UV-A LED, which is considered very high, demanding low electricity consumption in the process, whereas mercury vapor lamp and solar simulator yielded 19% and 13% inactivation efficiency, respectively. The best conditions were found with photocatalysts SiZnO, FNSiZnO and NSiZnO irradiated with UV-A LED, where efficiency exceeded 95% that matched inactivation of coliforms using the same irradiation and photocatalyst TiO2. All photocatalysts showed photocatalytic activity with all three radiation sources able to inactivate total coliforms from river water. The use of UV-A LED as the light source without photocatalyst is very promising, allowing the creation of cost-effective and highly efficient water treatment plants.

Screening the toxicity and biodegradability of petroleum hydrocarbons by a rapid colorimetric method.

Crude oil and petroleum products have a wide variety of hazardous components with high toxicity and low biodegradability. Certain dyes change their colors by intercepting electron transfer reactions during the transformation processes. This study applied resazurin and 2,6-dichlorophenol-indophenol indicators for a rapid screening biodegradation capability and toxicity response to various petroleum products such as motor oil, diesel, gasoline, and phenol. Colorimetry tests were performed in test tubes, and the absorbance values were measured over time. We observed different discoloration profiles after degradation tests using Bacillus subtilis inoculum. Phytotoxicity assays were also performed to compare colorimetric screening assays with a conventional toxicity testing with plants (seed germination). The results indicated that biotransformation of oils can increase its overall toxicity. Intermediate byproducts can be formed through biodegradation and thereby increase the toxicity of oils. The assessment of acute toxicity has shown that phenol is extremely toxic to petroleum-biodegrading microbial communities. Low molecular-weight gasoline was considered biodegradable, but it also exhibited a high acute toxic effect, mainly due to its high solubility and the presence of more volatile compounds that can penetrate cells and potentially damage cellular structures.

Assessing Bacillus subtilis biosurfactant effects on the biodegradation of petroleum products.

Microbial pollutant removal capabilities can be determined and exploited to accomplish bioremediation of hydrocarbon-polluted environments. Thus, increasing knowledge on environmental behavior of different petroleum products can lead to better bioremediation strategies. Biodegradation can be enhanced by adding biosurfactants to hydrocarbon-degrading microorganism consortia. This work aimed to improve petroleum products biodegradation by using a biosurfactant produced by Bacillus subtilis. The produced biosurfactant was added to biodegradation assays containing crude oil, diesel, and kerosene. Biodegradation was monitored by a respirometric technique capable of evaluating CO2 production in an aerobic simulated wastewater environment. The biosurfactant yielded optimal surface tension reduction (30.9 mN m(-1)) and emulsification results (46.90% with kerosene). Biodegradation successfully occurred and different profiles were observed for each substance. Precise mathematical modeling of biosurfactant effects on petroleum degradation profile was designed, hence allowing long-term kinetics prediction. Assays containing biosurfactant yielded a higher overall CO2 output. Higher emulsification and an enhanced CO2 production dataset on assays containing biosurfactants was observed, especially in crude oil and kerosene.

Biodegradation and toxicological evaluation of lubricant oils

The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei), arugula seeds (Eruca sativa) and lettuce seeds (Lactuca sativa), with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil) for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high. The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.

Photoeletrolytic system applied to remazol red brilliant degradation.

Toxicity tests using Sacharomycces cerevisiae were made with simulated textile effluents containing reactive dye (remazol red brilliant) treated by photoeletrolytic process, varying treatment time and applied current. The treatment incorporated an electrolytic reactor with rectangular titanium anode coated with 70% TiO(2)/30% RuO(2) cathode and a rectangular stainless steel coupled with another photolytic reactor containing a high power UV lamp. The treatment system was used in batch recirculation, in other words, the simulated effluent was driven by the system through a helical pump. It was observed that the higher the value of current applied, the longer the treatment has greater color removal of textile effluent and higher mortality of S. cerevisiae, killing up to 100% of the cells at the end of the treatment. With a lower current applied and having the treatment time of 5 minutes, the effluent showed a color removal of 97% and a lower mortality of S. cerevisiae than the effluent simulated without any treatment.

Studies on the electrochemical disinfection of water containing Escherichia coli using a Dimensionally Stable Anode

The aim of this work was to investigate the disinfectant effect of electrolysis on chlorine-free water, artificially contaminated with Escherichia coli (CCT-1457) and to evaluate the bactericidal activity of electrolysis and kinetic behavior of a single-cell reactor, with a DSA (Dimensionally Stable Anode) electrode to develop a scaled-up system. A high-density E. coli suspension (10(6) CFU mL-1) was electrolyzed in this reactor at 25, 50 and 75 mA cm-2 for up to 60 min, at flow rates of 200 and 500 L h-1. Bacterial survival fell by 98.9 percent without addition of chlorinated compounds and a power consumption rate not more than 5.60 kWh m-3 at flow rate of 200 L h-1 and 75 mA cm-2. The process produced a germicidal effect that reached this inactivation rate within a relatively short contact time. Also, a solution of electrolyzed 0.08 M Na2SO4 added to the inoculum showed residual bactericidal effect. The efficiency of disinfection was regulated by both the contact time and current density applied, and a kinetic function for the survival rate was developed for the purpose of scaling up.

Água contaminada é uma das maiores origens de doenças em seres humanos. Em todo o mundo, a cloração é o método mais utilizado para promover desinfecção em águas de abastecimento devido ao seu efeito residual, quando adequadamente calculado. Contudo, se a água apresentar matéria orgânica, pode haver a geração de organoclorados, os quais são genotóxicos e carcinogênicos. Sob esta óptica, investigamos o efeito bactericida da aplicação da eletrólise em água sem cloro contaminada com Escherichia coli (CCT-1457). O objetivo deste estudo foi avaliar o poder de desinfecção e o comportamento cinético da eletrólise realizada em reator de compartimento único e usando eletrodos ADE (Anodo Dimensionalmente Estável), visando ampliação de escala. Uma suspensão contendo elevada concentração de E. coli (10(6) UFC mL-1) foi submetida ao tratamento no reator em 25, 50 e 75 mA cm-2 durante 60 min, em vazões de 200 e 50 Lh-1. A taxa de inativação foi aproximadamente 99 por cento para a solução isenta de compostos clorados, com consumo de energia elétrica menor que 5,60 kWh m-3 em 200 L h-1 e 75 mA cm-2. Uma solução de Na2SO4 0,08M eletrolisada e adicionada posteriormente ao inoculo apresentou efeito residual bactericida. A eficiência da desinfecção foi regida pelo tempo de contato e pela densidade de corrente aplicada, e foi realizado um estudo cinético que permite a ampliação de escala.

Toxicity and biodegradation in sandy soil contaminated by lubricant oils.

The objective of this study was to evaluate the environmental behavior of different types of automotive lubricant oils. Based on respirometry assays the biodegradability was monitored, and toxicological tests were executed to assess the lubricants toxicity before and after microbial activity. Used oil was the most biodegradable, however, it was the most toxic. Also, all lubricants presented toxicity even after biodegradation due to 40% Eruca sativa germination inhibition and a low LC50 to Eisenia foetida (0.50-0.25 mL). Moreover, used automotive lubricants have a high toxicity because of polycyclic aromatic hydrocarbons concentration that establishes them as a potential carcinogen.

Evaluation of the biodegradation of different types of lubricant oils in liquid medium

The aim of this work was to study the biodegradation of different types of automotive lubricant oils adapted to the aqueous medium using a base inoculum and an aqueous inoculum. Four treatments were carried out in two consecutive and similar experiments: T1 (control); T2 (half-synthetic oil); T3 (mineral oil); T4 (used oil). The results showed the following decreasing order of CO2 production in the Bartha and Pramer respirometers: T4 > T2 > T3 > T1. Thus, the used lubricant oil showed with highest biodegradability, followed by the half-synthetic one and the mineral oil. It was also observed that the mineral lubricant presented a longer period of adaptation compared to the half-synthetic one.

Avaliação da Biodegradação de Diferentes Tipos de Óleo Lubrificante em Meio Aquoso pela Norma Técnica L6.350 (CETESB, 1990), utiliza-se o processo respirométrico de Bartha e Pramer para acompanhar a biodegradação de diferentes tipos de óleo lubrificante automotivo adaptado ao meio aquoso. Para realização do experimento foram preparados um inóculo base e, posteriormente, um inóculo aquoso. Quatro tratamentos foram realizados em dois experimentos consecutivos: T1 (controle); T2 (óleo semi-sintético); T3 (óleo mineral); T4 (óleo usado). Dentre os resultados, obteve-se a seguinte ordem decrescente na produção de CO2 nos respirômetros: T4 > T2 > T3 > T1. Assim, o óleo lubrificante usado surgiu com maior biodegradabilidade, seguido do semisintético e do óleo mineral. Observou-se também que o lubrificante mineral apresentou maior período de adaptação comparado ao semisintético.

Planta piloto de um processo eletrolítico em indústria de aditivos para borracha / Pilot plant of an electrolytic process in a rubber additive industry

O efluente de uma indústria produtora de aditivos para borracha foi submetido a um tratamento eletrolítico em vários tempos de eletrólises objetivando principalmente a diminuição da cor do efluente industrial e melhora nos parâmetros preconizados pela legislação brasileira de águas. O tratamento eletrolítico foi construído em uma planta piloto logo após o tratamento físico-químico e biológico realizado pela indústria química. O efluente, após passar pelo tratamento convencional da empresa, apresentou cor marrom e bastante turva, 1592 mg/L de demanda química de oxigênio (DQO), 873 mg/L de demanda bioquímica de oxigênio (DBO) e 1,30 mg/L de ferro solúvel. Após 60 min de eletrólise, este efluente estava incolor, possuía 1004 mg/L de DQO, 593 mg/L de DBO e 0,66 mg/L de ferro solúvel...

Color and characterization of an industry effluent was studied through electrolytic process at various times, before and after it has passed by the treatment process of the industry. A pilot system for electrolyte treatment was installed in the final effluent. After the electrolysis, it was examined for color and the other parameters of the Brazilian regulations (Article 18, CONAMA 357). The non-electrolysed effluent had brown color and rather cloudy, 1592 mg/L of COD, 873 mg/L of BOD, 1.30 mg/L of soluble iron. After 60 minutes of electrolysis, the effluent was colorless, had 1004 mg/Lof COD, 593 mg/L of BOD and 0.66 mg/L of soluble iron. The electrolyzed effluent could be used again by the industry reducing the use of tap water...

Effect of surfactant in automotive lubrificant oil biodegradability

The Bartha and Pramer’s respirometric method was used to monitor the biodegradation of automotive lubricant oil in aqueous medium and to evaluate the effect of adding the surfactant Tween 80®. It was prepared a base and an aqueous inoculums with and without the surfactant, and the microbiota metabolism was measured by chemical analysis in quantifying the CO2 production in respirometers. Three treatments were carried out: T1 (without Tween 80®); T2 (with Tween80®) and T3 (with Tween 80® and used lubricant oil). The results presented the following crescent order of accumulated CO2: T1 < T2 < T3. It was concluded that the used lubricant oil was degraded by microorganisms and Tween 80® maximized the oil biodegrability due to the micellization process with the lubricant oil...

O método respirométrico de Bartha e Pramer foi utilizado para acompanhar a biodegradação de óleo lubrificante automotivo em meio aquoso e para avaliar a influência da adição do surfactante Tween 80®. Para realização do experimento, foram preparados uminóculo base e um inóculo aquoso, e a ação microbiana foi monitorada por análise química na quantificação da produção de CO2 nos respirômetros. Três tratamentos foram realizados: T1 (sem Tween 80®); T2 (com Tween 80®); e T3 (com Tween 80® e óleo lubrificante usado). Os resultados apresentaram a seguinte sequência crescente de CO2 acumulado: T1 < T2 < T3. Concluiu-se, portanto, que oóleo lubrificante usado foi de composto pelos microrganismos e que o Tween 80® melhorou a biodegradabilidade do óleo devido ao processo de micelização realizado junto ao óleo lubrificante...