RESUMO
Large volumes of produced water are generated as a byproduct in activities of oil and gas exploitation, which can be reused in agriculture after a treatment process. Activated sludge treatment has been successfully used to remove oil from wastewater, but systematic studies on the toxicity of this effluent using this treatment are scarce in the literature. In this study, it was investigated the performance of an activated sludge system in the treatment of a synthetic produced water under different initial conditions in terms of salinity and oil and grease concentration. Furthermore, it was evaluated this effluent phytotoxicity in the germination, and seedling and plant growths of sunflower and corn seeds using untreated and treated synthetic produced water. Results revealed the activated sludge effectiveness in oil and grease and salinity removal from produced water, viz. high removal efficiency of 99.01 ± 0.28 and 91.07 ± 0.39%., respectively. Untreated produced water showed considerable toxic effects on the germination (74.67 ± 2.31% and 82.67 ± 2.31 for sunflower and corn seeds, respectively) and growth stages of sunflower and corn seed plants. The germination percentage was approximately 100% for both types of seed. The seedling and plant growth of the two seeds irrigated with treated produced water had similar performance when used tap water. These results highlighted the potential reuse as an unconventional water resource for plant irrigation of the synthetic produced water treated by an activated sludge process, which technology has showed high removal performance of salinity and oil.
Assuntos
Irrigação Agrícola , Germinação , Helianthus/crescimento & desenvolvimento , Reciclagem , Esgotos/química , Eliminação de Resíduos Líquidos/instrumentação , Zea mays/crescimento & desenvolvimento , Germinação/efeitos dos fármacos , Helianthus/efeitos dos fármacos , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Águas Residuárias/análise , Zea mays/efeitos dos fármacosRESUMO
Sanitary landfill leachates usually have characteristics that depend on the region where they are generated and according to the age of the landfill, which is why a unique treatment for their sanitation has not been found. However, the adsorption preceded by the Fenton process has been proven to be highly efficient at removing contaminants. In this study, the adsorptive capacity of two types of activated carbon, granular and powdered, was analyzed to determine which was more efficient in the adsorption stage in the Fenton-adsorption process. Likewise, its behavior was analyzed using three isotherm models (Langmuir, Freundlich and Temkin), testing the raw leachate and the Fenton-treated one with both carbons. The adsorption that is carried out on the carbons is better adjusted to the Freundlich and Temkin models. It concludes that multilayers, through the physical adsorption, carry out the adsorption of pollutants on the surface of the carbons. The results show that, statistically, granular activated carbon is more efficient at removing chemical oxygen demand (COD), and powdered activated carbon removes color better. Finally, an adsorption column was designed for the Fenton-adsorption process that was able to remove 21.68 kgCOD/kg carbon. Removal efficiencies for color and COD were >99%.
Assuntos
Carvão Vegetal/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Análise da Demanda Biológica de Oxigênio , México , Modelos Químicos , Tamanho da Partícula , Pós/química , Eliminação de Resíduos Líquidos/instrumentaçãoRESUMO
This study assessed the applicability of fixed bed bioreactors in two configurations - anaerobic structured bed reactor (ASBR) and anaerobic packed bed reactor (APBR) - in the removal of Sulfamethoxazole (SMX) and Ciprofloxacin (CIP), two antibiotics frequently detected in sanitary sewage. The problem of these pharmaceuticals as emerging contaminants in conventional sewage treatment systems is mainly because they encourage the development and spread of resistance genes in bacteria. Both reactors had similar performances, and the antibiotics were highly removed - APBR: 85⯱â¯10% for SMX and 81⯱â¯16% for CIP; ASBR: 83⯱â¯12% for SMX and 81⯱â¯15% for CIP. The ASBR showed to be potentially more feasible in operating and economic terms compared to the APBR, as the former presents a smaller amount of support material in the bed. SMX was completely biotransformed, while the influence of the sorption mechanism was observed for CIP, as its presence was detected sorbed onto biomass throughout the reaction bed of the reactors, with a partition coefficient (log KD) of around 2.8â¯L·kg-1TSS. The degradation kinetics of the pharmaceuticals were fitted using a first-order kinetic model, whereby the reactors behaved as plug flow ones, indicating the possibility of optimizing the operation for a hydraulic retention time of 6â¯h. The removal kinetics was more favorable for CIP (higher apparent constant kinetic - kCIPappâ¯>â¯kSMXapp), since its biodegradation is linked to the biomass, which is more concentrated in the bed bottom layer. The experimental results showed the potential of anaerobic fixed bed reactors in removing environmentally relevant concentrations of SMX and CIP found in sewage.
Assuntos
Reatores Biológicos , Ciprofloxacina/análise , Esgotos/análise , Sulfametoxazol/análise , Eliminação de Resíduos Líquidos/instrumentação , Poluentes Químicos da Água/análise , Anaerobiose , Antibacterianos/análise , Anti-Infecciosos/análise , Reatores Biológicos/classificação , BrasilRESUMO
The use of ultraviolet light in photoreactors for wastewater treatment has become popular as an alternative of known chemical oxidative substances. UV LED light represents cheaper, robust, and versatile alternative to traditional UV lamps. In this study, it was designed and evaluated a photoreactor with an approach of chemical fluid dynamics (CFD) and experimental validation. The evaluation consisted of (1) CFD velocity profile analysis, (2) characterization of the average light distribution with potassium ferrioxalate actinometry, (3) degradation of a typical recalcitrant metallic cyanocomplex Fe(CN)63-, and (4) scavenger effect analysis in the photodegradation using potassium persulfate. Actinometrical essay concluded that the system was able to receive 1.93 µE/s. The reactor operated under turbulent regime and best result for Fe(CN)63- degradation was obtained at 4 h of operation, using 5-W UV-A LEDs, with pH ~ 7 and 10 mM de S2O82-. Baffled photoreactor demonstrated to be useful for this type of illumination and wastewater treatment.
Assuntos
Mineração , Eliminação de Resíduos Líquidos/instrumentação , Eliminação de Resíduos Líquidos/métodos , Desenho de Equipamento , Ferrocianetos/química , Hidrodinâmica , Oxalatos/química , Oxirredução , Fotólise , Compostos de Potássio/química , Sulfatos/química , Raios Ultravioleta , Águas Residuárias/químicaRESUMO
The aim of the present study was to investigate the separation of oil from water using a bench-scale DAF prototype with the addition of biosurfactants isolated from Pseudomonas cepacia CCT6659 and Bacillus cereus UCP1615. The best operating conditions for the DAF prototype were determined using a central composite rotatable design. The results demonstrated that the biosurfactants from P. cepacia and B. cereus increased the oil separation efficiency from 53.74% (using only microbubbles) to 94.11 and 80.01%, respectively. The prediction models for both DAF-biosurfactant systems were validated, showing an increase in the efficiency of the DAF process from 53.74% to 98.55 and 70.87% using the formulated biosurfactants from P. cepacia and B. cereus, respectively. The biosurfactant from P. cepacia was selected as the more promising product and used for the treatment of oily effluent from a thermoelectric plant, achieving removal rates ranging between 75.74 (isolated biosurfactant) and 95.70% (formulated biosurfactant), respectively.
Assuntos
Resíduos Industriais/análise , Tensoativos , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Ar , Bacillus cereus/classificação , Burkholderia cepacia/química , Desenho de Equipamento , Óleos Industriais/análise , Tensoativos/isolamento & purificação , Eliminação de Resíduos Líquidos/instrumentação , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/instrumentaçãoRESUMO
Biofilm-based wastewater treatment systems have become attractive due to their numerous advantages when compared to other suspended growth processes. However, the mathematical modeling of these reactors is relatively complex, since it has to consider a wide range of phenomena to accurately describe the process behavior. This work deals with the modeling of a two-stage MBBR system run in pre-denitrification mode for the removal of organic matter and nitrogen from wastewater. The model development took into account diffusive phenomena and kinetics in a homogeneous biofilm composed of different bacterial functional groups (namely heterotrophs and nitrifiers). The thickness of the biofilm was treated as a variable, given that detachment of adhered biomass took place. The suspended biomass fraction was also considered to remove the pollutants by means of Monod-type kinetics associated with the activated sludge model. The dynamic behavior of the components involved in the system and their spatial distribution in the biofilm obtained from simulated data showed good agreement with those reported in the literature, demonstrating the reproducibility of the model and encouraging future applications in full-scale MBBR plants.
Assuntos
Biofilmes , Reatores Biológicos , Eliminação de Resíduos Líquidos/instrumentação , Biomassa , Reatores Biológicos/microbiologia , Simulação por Computador , Desnitrificação , Difusão , Cinética , Modelos Teóricos , Reprodutibilidade dos Testes , Eliminação de Resíduos Líquidos/estatística & dados numéricos , Águas ResiduáriasRESUMO
A set of experiments were conducted in Brazil in a pilot-scale waste stabilization pond (WSP) system (a four-maturation-pond series) treating an upflow anaerobic sludge blanket (UASB) reactor effluent. Over a year and a half the pond series was monitored under two flow rate conditions, hence also different hydraulic retention times and surface loading rates. On-site and laboratory trials were carried out to assess: (i) ammonia losses by volatilization using acrylic capture chambers placed at the surface of the ponds; (ii) organic nitrogen sedimentation rates using metal buckets placed at the bottom of the ponds for collecting settled particulate matter; (iii) nitrogen removal by algal uptake based on the nitrogen content of the suspended particulate matter in samples from the ponds' water column. In addition, nitrification and denitrification rates were measured in laboratory-based experiments using pond water and sediment samples. The pond system achieved high nitrogen removal (69% total nitrogen and 92% ammonia removal). The average total nitrogen removal rates varied from 10,098 to 3,849 g N/ha·d in the first and the last ponds, respectively, with the following fractions associated with the various removal pathways: (i) 23.5-45.6% sedimentation of organic nitrogen; (ii) 13.1-27.8% algal uptake; (iii) 1.2-3.1% ammonia volatilization; and (iv) 0.15-0.34% nitrification-denitrification.
Assuntos
Amônia/metabolismo , Nitrogênio/metabolismo , Lagoas , Eliminação de Resíduos Líquidos/métodos , Reatores Biológicos , Brasil , Desnitrificação , Sedimentos Geológicos/análise , Nitrificação , Projetos Piloto , Esgotos , Volatilização , Eliminação de Resíduos Líquidos/instrumentaçãoRESUMO
A four stage semi-pilot scale RFR reactor with ceramic disks as support for TiO2 modified with silver particles was developed for the removal of organic pollutants. The design presented in this article is an adaptation of the rotating biological reactors (RBR) and its coupling with the modified catalyst provides additional advantages to designs where a catalyst in suspension is used. The optimal parameter of rotation was 54 rpm and the submerged surface of the disks offer a total contact area of 387 M². The modified solid showed a decrease in the value of its bandgap compared to commercial titanium. The system has a semi-automatic operation with a maximum reaction time of 50 h. Photo-activity tests show high conversion rates at low concentrations. The results conform to the Langmuir heterogeneous catalysis model.
Assuntos
Prata/química , Titânio/química , Purificação da Água/instrumentação , Catálise , Cinética , Luz , Oxirredução , Processos Fotoquímicos , Propriedades de Superfície , Termodinâmica , Eliminação de Resíduos Líquidos/instrumentaçãoRESUMO
Palm oil mill wastes (palm kernel shell (PKS)) were used to prepare activated carbons, which were tested in the removal of colorants from water. The adsorbents were prepared by 1-h impregnation of PKS with ZnCl2 as the activating agent (PKS:ZnCl2 mass ratios of 1:1 and 2:1), followed by carbonization in autogenous atmosphere at 500 and 550 °C during 1 h. The characterization of the activated carbons included textural properties (porosity), surface chemistry (functional groups), and surface morphology. The dye removal performance of the different activated carbons was investigated by means of the uptake of methylene blue (MB) in solutions with various initial concentrations (25-400 mg/L of MB) at 30 °C, using a 0.05-g carbon/50-mL solution relationship. The sample prepared with 1:1 PKS:ZnCl2 and carbonized at 550 °C showed the highest MB adsorption capacity (maximum uptake at the equilibrium, q max = 225.3 mg MB / g adsorbent), resulting from its elevated specific surface area (BET, 1058 m2/g) and microporosity (micropore surface area, 721 m2/g). The kinetic experiments showed that removals over 90% of the equilibrium adsorptions were achieved after 4-h contact time in all the cases. The study showed that palm oil mill waste biomass could be used in the preparation of adsorbents efficient in the removal of colorants in wastewaters.
Assuntos
Carvão Vegetal/química , Corantes/química , Azul de Metileno/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Resíduos Industriais , Nozes/química , Óleo de Palmeira , Eliminação de Resíduos Líquidos/instrumentaçãoRESUMO
The present work evaluated the effects of (i) feeding a water contaminated with 80 mg/L PCE to bioreactors seeded with inoculum not acclimated to PCE, (ii) coupling ZVI side filters to bioreactors, and (iii) working in different biological regimes, i.e., simultaneous methanogenic aeration and simultaneous methanogenic-denitrifying regimes, on fluidized bed bioreactor performance. Simultaneous electron acceptors refer to the simultaneous presence of two compounds operating as final electron acceptors in the biological respiratory chain (e.g., use of either O2 or NO3- in combination with a methanogenic environment) in a bioreactor or environmental niche. Four lab-scale, mesophilic, fluidized bed bioreactors (bioreactors) were implemented. Two bioreactors were operated as simultaneous methanogenic-denitrifying (MD) units, whereas the other two were operated in partially aerated methanogenic (PAM) mode. In the first period, all bioreactors received a wastewater with 1 g chemical oxygen demand of methanol per liter (COD-methanol/L). In a second period, all the bioreactors received the wastewater plus 80 mg perchloroethylene (PCE)/L; at the start of period 2, one MD and one PAM were coupled to side sand-zero valent iron filters (ZVI). All bioreactors were inoculated with a microbial consortium not acclimated to PCE. In this work, the performance of the full period 1 and the first 60 days of period 2 is reported and discussed. The COD removal efficiency and the nitrate removal efficiency of the bioreactors essentially did not change between period 1 and period 2, i.e., upon PCE addition. On the contrary, specific methanogenic activity in PAM bioreactors (both with and without coupled ZVI filter) significantly decreased. This was consistent with a sharp fall of methane productivity in those bioreactors in period 2. During period 2, PCE removals in the range 86 to 97 % were generally observed; the highest removal corresponded to PAM bioreactors along with the highest dehalogenation efficiency (94 %). Principal component analysis as well as cluster analysis confirmed the trends mentioned above, i.e., the better performance of PAM over MD, and the unexpected no effect of the ZVI side filters on PCE removal and dehalogenation efficiencies. To the best of our knowledge, this is the first report on the combined treatment ZVI-biological of a water polluted with PCE, where the biological operation relied on simultaneous electron acceptors.