Advanced oxidation of recalcitrant chromophores in full-scale MBR effluent for non-potable reuse of leachate co-treated municipal wastewater.

Wastewater non-potable reuse involves further processing of secondary effluent to a quality level acceptable for reuse and is a promising solution to combating water scarcity. Recalcitrant chromophores in landfill leachate challenge the water quality for non-potable reuse when leachate is co-treated with municipal wastewater. In this study, we first use multivariate statistical analysis to reveal that leachate is an important source (with a Pearson's coefficient of 0.82) of recalcitrant chromophores in the full-scale membrane bioreactor (MBR) effluent. We then evaluate the removal efficacies of chromophores by chlorination, breakpoint chlorination, and the chlorination-UV/chlorine advanced oxidation treatment. Conventional chlorination and breakpoint chlorination only partially remove chromophores, leaving a colour level exceeding the standards for non-potable reuse (>20 Hazen units). We demonstrate that pre-chlorination (with an initial chlorine dosing of 20 mg/L as Cl2) followed by UV radiation (with a UV fluence of 500 mJ/cm2) effectively degraded recalcitrant chromophores (>90%). By quantifying the electron donating capacity (EDC) and radical scavenging capacity (RSC) of the reclaimed water, we demonstrate that pre-chlorination reduces EDC and RSC by up to 64%, increases UV transmittance by 32%, and increases radical yields from UV photolysis of chlorine by 1.7-2.2 times. The findings advance fundamental understanding of the alteration of dissolved coloured substances by (photo)chlorination treatment and provide implications for applying advanced oxidation processes in treating wastewater effluents towards sustainable non-potable reuse.

Development of a full-scale wastewater treatment plant for licorice root processing factories: A hybrid biodegradation-lime-alum-ozonation process.

Liquorice is a perennial legume that grows principally in Asia, the Middle East and some parts of Europe. The sweet root extract is mainly used in the pharmaceutical, food and confectionary industries. It contains 400 compounds, including triterpene saponins and flavonoids, which are responsible for liquorice's bioactivities. The wastewater (WW) arising from the processing of liquorice can have negative environmental effects and must be treated before being discharged into the environment. Different WW treatment solutions are available. In the last years, increasing attention has been paid to the environmental sustainability of wastewater treatment plants (WWTPs). The present article discusses a hybrid biological (anaerobic-aerobic) and post-biological (lime-alum-ozone) WWTP, designed to treat 105 m3/day complex liquorice root extract WW for agricultural purposes. The influent chemical oxygen demand (COD) and biological oxygen demand (BOD5) were found to be 6000-8000 mg/L and 2420-3246 mg/L, respectively. With a biological hydraulic retention time of 8.2 days and no addition of extra nutrients, the WWTP reached a stable condition after 5 months. Over the course of 16 months, its highly efficient biological treatment reduced COD, BOD5, total suspended solids (TSS), phosphate, ammonium, nitrite, nitrate and turbidity by 86-98 %. However, the WW's colour proved resilient: only 68 % of the colour was removed by the biological treatment, necessitating a combination of biodegradation-lime-alum-ozonation processes in order to reach 98 % efficiency. Thus, this study reveals that liquorice root extract WW can successfully be treated and reused for crop irrigation.

Wastewater from textile digital printing as a substrate for microalgal growth and valorization.

This study aims at evaluating an innovative biotechnological process for the concomitant bioremediation and valorization of wastewater from textile digital printing technology based on a microalgae/bacteria consortium. Nutrient and colour removal were assessed in lab-scale batch and continuous experiments and the produced algae/bacteria biomass was characterized for pigment content and biomethane potential. Microbial community analysis provided insight of the complex community structure responsible for the bioremediation action. Specifically, a community dominated by Scenedesmus spp. and xenobiotic and dye degrading bacteria was naturally selected in continuous photobioreactors. Data confirm the ability of the microalgae/bacteria consortium to grow in textile wastewater while reducing the nutrient content and colour. Improvement strategies were eventually identified to foster biomass growth and process performances. The experimental findings pose the basis of the integration of a microalgal-based process into the textile sector in a circular economy perspective.

Dyeing wastewater treatment in horizontal-vertical constructed wetland using organic waste media.

A hybrid constructed wetland (CW) system with horizontal and vertical flow combination was evaluated for treating carbon-deficient synthetic dyeing wastewater containing 100 mg/L Reactive Yellow 145 dye. Organic waste products such as cow manure and wood chips were added as media in horizontal CW, and gravel as vertical CW media. Horizontal and vertical CWs were planted with Typha angustifolia. Horizontal CW was operated in continuous mode at hydraulic retention time (HRT) of 3 d and vertical CW in batch mode at 1 d HRT. The results suggested the potential application of a cost-effective horizontal-vertical hybrid CW to remove azo dyes from low-carbon dyeing wastewater. In horizontal CW, organic media was used as the carbon source for microbial dye degradation, resulting in 90% colour removal in the absence of available carbon in dyeing wastewater. Proteobacteria, Firmicutes and Bacteroidetes played a dominant role in dye degradation in horizontal CW. Vertical CW removed dye degradation organics, 69% ammonium-nitrogen and 39% organic-nitrogen. Phytotoxicity assays indicated toxicity reduction along the CW treatment path.

Integrated emergent-floating planted reactor for textile effluent: Removal potential, optimization of operational conditions and potential forthcoming waste management strategy.

Native emergent and floating plants; local reed grass (Phragmites karka) and water hyacinth (Eichhornia crassipes), respectively, were used to treat textile wastewater using an integrated emergent-floating planted reactor (IEFPR) system at hydraulic retention times (HRTs) of 8, 14, and 19 days. Real textile effluent having characteristics of 1686.3 ADMI for colour, 535 mg/L for total suspended solid (TSS), 647.7 mg/L for chemical oxygen demand (COD) and 124 mg/L for biochemical oxygen demand (BOD) was used throughout this study. The IEFPR system experienced maximum removal of colour (94.8%, HRT 14 days, day 3), TSS (92.7%, HRT 19 days, day 7), and COD (96.6%, HRT 8 days, day 5) at different HRT and exposure time. The process conditions (HRT and exposure time) were optimized for maximum colour, TSS and COD removal from textile effluent by employing response surface methodology (RSM). The optimization has resulted 100% removal of colour, 87% removal of TSS and 100% removal of COD at HRT of 8 days and exposure time of 5 days, with 0.984 desirability. The integrated plant-assisted treatment system showed reliable performance in treating textile wastewater at optimum operational conditions to improve effluent quality before disposal into water bodies or being recycled into the process. The potential of phytoremediator (produced plant biomass) to be utilized as resources for bioenergy or to be converted into value added products (adsorbent or biochar) provides an alternative to management strategy for better environmental sustainability.

An artificial neural network combined with response surface methodology approach for modelling and optimization of the electro-coagulation for cationic dye.

An artificial neural network (ANN) approach with response surface methodology (RSM) technique has been applied to model and optimize the removal process of Brilliant Green dye by batch electrocoagulation process. A multilayer perceptron (MLP) - ANN model has been trained by four input neurons which represent the reaction time, current density, pH, NaCl concentration, and two output neurons representing the dye removal efficiency (%) and electrical energy consumption (kWh/kg). The optimized hidden layer neurons were obtained based on a minimum mean squared error. The batch electrocoagulation process was optimized using central composite design with RSM once the ANN network was trained and primed to anticipate the output. At optimized condition (electrolysis time 10 min, current density 80 A/m2, initial pH 5 and electrolyte NaCl concentration 0.5 g/L), RSM projected decolorization of 98.83% and electrical energy consumption of 14.99 kWh/kg. This study shows that the removal of brilliant green dye can be successfully carried out by a batch electrocoagulation process. Therefore, the process is successfully trained by ANN and optimized by RSM for similar applications.

Evaluation of the efficiency of coagulation/flocculation and Fenton process in reduction of colour, turbidity and COD of a textile effluent.

The present study investigated the efficiency of physicochemical processes of coagulation and flocculation and Fenton advanced oxidative process in reducing the parameters of colour, turbidity and Chemical Oxygen Demand (COD) of a real effluent from a textile industry. During the physicochemical process, the efficiencies of different coagulants (aluminium polychloride (Polifloc 18), ferric chloride (Acquafloc FC40), aluminium sulphate combined with organic coagulant (AST) and aluminium sulphate) and nonionic (FX NS2), cationic (FX CS6 and FX CS7) and anionic (FX AS6 and AN905) flocculants were tested. After the tests, 72.60% of COD, 36.25% of colour and 98.59% of turbidity were removed, using aluminium polychloride coagulant and AN 905 flocculant. It was also evaluated the effect of Fenton advanced oxidative process application in removal of colour, COD and turbidity of the effluent previously treated through the physicochemical process. Removals of these parameters were analysed in two different pH ranges (pH 6.0 and 7.0). In both pH 6.0 and pH 7.0, reductions were observed in all analysed parameters, obtaining 170.78 mg O2/L of COD, 22.19 mg/L of colour and 0.80 NTU of turbidity (at pH 6.0) and 151.80 mg O2/L of COD, 26.73 mg/L of colour, 0.94 NTU of turbidity (at pH 7.0), which demonstrates the efficiency of this process in the reduction of parameters analysed.

Adsorption kinetics of colour removal from palm oil mill effluent using wastewater sludge carbon in column studies.

Treated palm oil mill effluents (POME) is of great concern as it still has colour from its dissolved organics which may pollute receiving water bodies. In this study, the removal of colour from treated palm oil mill effluent were investigated through adsorption studies using carbon derived from wastewater sludge (WSC). Sludge from activated sludge plants were dried and processed to produce WSC. In this study, three different bed depths of WSC were used: 5 cm, 10 cm, and 15 cm. For each bed depth, the flowrate was varied at three different values: 100 mL/hr, 50 mL/hr and 25 mL/hr. It was found that at bed depth of 5 cm, the breakthrough curves were occurred at 360 min, 150 min and 15 min for flowrates of 25, 50 and 100 mL/hr respectively. It was observed that at a particular depth the exhaustion time for column reduced as flow rate increases. Kinetic models, Adams-Bohart and Yoon-Nelson were used to analyze the performance of the adsorption. It was found that rate constant for Adams Bohart model decreased with the increase in bed depth. Adsorption capacity obtained from Adams-Bohart model ranged from 2676.19 mg/L up to 8938.78 mg/L. The maximum adsorption capacity increases with smaller bed depth. For Yoon-Nelson model, the rate constant decreases with increase in bed depth. The required time for 50% breakthrough obtained from the models ranged from 17.01 to 104.17 minutes for all three bed depths. The reduction of colour was found to be effective at all bed depths. The experimental data was best described by both models as with higher values of correlation coefficient (R2).

Modelling dye removal by adsorption onto water treatment residuals using combined response surface methodology-artificial neural network approach.

In this study, response surface methodology (RSM)-artificial neural network (ANN) approach was used to optimise/model disperse dye removal by adsorption using water treatment residuals (WTR). RSM was first applied to evaluate the process using three controllable operating parameters, namely WTR dose, initial pH (pHinitial) and dye concentration, and optimal conditions for colour removal were determined. In the second step, the experimental results of the design data of RSM were used to train the neural network along with a non-controllable parameter, the final pH (pHfinal). The trained neural networks were used for predicting the colour removal. A colour removal of 52.6 ±â€¯2.0% obtained experimentally at optimised conditions (pHinitial 3.0, adsorbent dose 30 g/L and dye concentration 75 mg/L) was comparable to 52.0% and 52.2% predicted by RSM and RSM-ANN, respectively. This study thus shows that optimising/predicting the colour removal process using the RSM-ANN approach is possible, and it also indicates that adsorption onto WTR could be used as a primary treatment for removal of colour from dye wastewater.

The Pertinence of Microwave Irradiated Coconut Shell Bio-Sorbent for Wastewater Decolourization: Structural Morphology and Adsorption Optimization Using the Response Surface Method (RSM).

Palm oil mill effluent contains carcinogenic coloured compounds that are difficult to separate due to their aromatic structure. Though colour treatment using adsorption processes at lower pH (<4) have been reported effectual, due to its acidity the remediated effluent poses an environmental hazard as a result. Thus, the current study focused on achieving decolourization at neutral pH by enhancing the morphology of the coconut shell activated carbon (CSAC) using N2 as activating-agent with microwave irradiation heating. The microwave pretreated and non-pretreated CSAC were characterized using scanned electron microscopy (SEM), energy dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) analysis. A significant modification in the porous structure with a 66.62% increase in the specific surface area was achieved after the pretreatment. The adsorption experimental matrix was developed using the central composite design to investigate the colour adsorption performance under varied pH (6⁻7), dosage (2⁻6 g) and contact time (10⁻100 min). At optimum conditions of neutral pH (7), 3.208 g dosage and contact time of 35 min, the percentage of colour removal was 96.29% with negligible differences compared with the predicted value, 95.855%. The adsorption equilibrium capacity of 1430.1 ADMI × mL/g was attained at the initial colour concentration of 2025 ADMI at 27 °C. The experimental data fitted better with the Freundlich isotherm model with R² 0.9851.

Elucidating efficacy of biomass derived nanocomposites in water and wastewater treatment.

In the present study, two synthesis methods of nanocomposites-one involving a mixture of biomass and the other using chemical modification were investigated to evaluate practical application of green approach in pollution control, specifically for water and wastewater treatment. Newer multifunctional superparamagnetic nanocomposites using biomaterials such as unripened fruit of Cassia fistula (Golden shower) and Aloe vera were developed as an example of green approach while chemical modification was illustrated using n-octanol. Two specific model applications were studied for the developed materials-dye removal (Methyl Blue and Congo Red) and disinfection-demonstrating antimicrobial property. To elucidate the multifunctional character, the texture, morphology and composition of the prepared bionanocomposites were studied. The surface area values were 6.2 and 9.8 m2/g for Aloe vera and octanol based nanocomposites while the average pore diameters were 1.79 nm and 5.7 nm respectively, indicating presence of highly developed micropores in the first material having a honeycomb shape and the later showing excellent staircase type formation with larger pores. A very high dye removal to the extent of 100% was obtained that can be attributed largely to the functionalities imparted from Cassia fistula compared to ingredients from Aloe vera and octanol. The nanomaterials could be completely separated with absolute ease by applying simple magnetic field. Also, successful application of the developed materials in disinfection, removal of E. coli, was demonstrated with a very high efficiency of over 95%. The biomass derived nanocomposites exhibit excellent pollutant removal and disinfection properties, even at very low nanoparticle content; octanol based material indicating ∼5 times lowered cost, while the Aloe vera based bionanocomposites have potential for cost reduction to the extent of 10 times as compared to only magnetite nanoparticles, thereby highlighting techno-economical alternative in water and wastewater treatment.

Enzymatic catalysis treatment method of meat industry wastewater using lacasse.

BACKGROUND: The process of meat industry produces in a large amount of wastewater that contains high levels of colour and chemical oxygen demand (COD). So they must be pretreated before their discharge into the ecological system. METHODS: In this paper, enzymatic catalysis (EC) was adopted to treat the meat wastewater. RESULTS: Box-Behnken design (BBD), an experimental design for response surface methodology (RSM), was used to create a set of 29 experimental runs needed for optimizing of the operating conditions. Quadratic regression models with estimated coefficients were developed to describe the colour and COD removals. CONCLUSIONS: The experimental results show that EC could effectively reduce colour (95 %) and COD (86 %) at the optimum conditions of enzyme dose of 110 U/L, incubation time of 100 min, pH of 7 and temperature of 40 °C. RSM could be effectively adopted to optimize the operating multifactors in complex EC process.

Advanced treatment of swine wastewater using an agent synthesized from amorphous silica and hydrated lime.

Advanced treatment using an agent synthesized from amorphous silica and hydrated lime (M-CSH-lime) was developed and applied to swine wastewater treatment. Biologically treated wastewater and M-CSH-lime (approximately 6 w/v% slurry) were fed continuously into a column-shaped reactor from its bottom. Accumulated M-CSH-lime gradually formed a bed layer. The influent permeated this layer and contacted the M-CSH-lime, and the treatment reaction progressed. Treated liquid overflowing from the top of the reactor was neutralized with CO2gas bubbling. The colour removal rate approximately exceeded 50% with M-CSH-lime addition rates of > 0.15 w/v%. The removal rate of PO(3⁻)(4) exceeded 80% with the addition of>0.03 w/v% of M-CSH-lime. The removal rates of coliform bacteria and Escherichia coli exceeded 99.9% with > 0.1 w/v%. Accumulated M-CSH-lime in the reactor was periodically withdrawn from the upper part of the bed layer. The content of citric-acid-soluble P2O5 in the recovered matter was>15% when the weight ratio of influent PO(3⁻)(4) -P to added M-CSH-lime was > 0.15. This content was comparable with commercial phosphorus fertilizer. The inhibitory effect of recovered M-CSH-lime on germination and growth of leafy vegetable komatsuna (Brassica rapa var. perviridis) was evaluated by an experiment using the Neubauer's pot. The recovered M-CSH-lime had no negative effect on germination and growth. These results suggest that advanced water treatment with M-CSH-lime was effective for simultaneous removal of colour, [Formula: see text] and coliform bacteria at an addition rate of 0.03-0.15 w/v%, and that the recovered M-CSH-lime would be suitable as phosphorus fertilizer.

Use of Bacillus pumilus CBMAI 0008 and Paenibacillus sp. CBMAI 868 for colour removal from paper mill effluent / Emprego de Bacillus pumilus CBMAI 0008 e Paenibacillus sp. CBMAI 868 para remoção da cor do efluente da indústria papeleira

Bacillus pumilus and Paenibacillus sp. were applied on the paper mill effluent to investigate the colour remotion. Inocula were individually applied in effluent at pH 7.0, 9.0 and 11.0. The real colour and COD remotion after 48h at pH 9.0 were, respectively, 41.87% and 22.08% for B. pumilus treatment and 42.30% and 22.89% for Paenibacillus sp. Gel permeation chromatography was used to verify the molar masses of compounds in the non-treated and treated effluent, showing a decrease in the compounds responsible for the paper mill effluent colour.

Bacillus pumilus e Paenibacillus sp. foram aplicados separadamente no efluente da indústria papeleira a pH 7,0, 9,0 e 11,0, para verificação da remoção da cor e da DQO. As remoções da cor real e DQO após 48h a pH 9,0 foram, respectivamente, de 41,87% e 22,08% após o tratamento com B. pumilus e 42,30% e 22,89% após tratamento com Paenibacillus sp. As massas molares dos compostos presentes no efluente não tratado e tratado foram determinadas por cromatografia de permeação em gel. O emprego dos microrganismos reduziu os compostos responsáveis pela cor do efluente da indústria papeleira.

Use of Bacillus pumilus CBMAI 0008 and Paenibacillus sp. CBMAI 868 for colour removal from paper mill effluent.

Bacillus pumilus and Paenibacillus sp. were applied on the paper mill effluent to investigate the colour remotion. Inocula were individually applied in effluent at pH 7.0, 9.0 and 11.0. The real colour and COD remotion after 48h at pH 9.0 were, respectively, 41.87% and 22.08% for B. pumilus treatment and 42.30% and 22.89% for Paenibacillus sp. Gel permeation chromatography was used to verify the molar masses of compounds in the non-treated and treated effluent, showing a decrease in the compounds responsible for the paper mill effluent colour.