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The tofu industry generates substantial liquid waste that poses environmental challenges due to its high chemical oxygen demand (COD), total suspended solids (TSS), and pH levels. This study aimed to determine the effectiveness of Eco Enzymes in reducing these chemical parameters in the tofu industry waste in Klumutan Village, Saradan District. Utilizing a Quasi-Experimental method, the research employed purposive sampling of liquid waste from tofu production. The findings revealed that the application of Ecoenzyme at doses of 5%, 10%, and 15%, with detention times of 10, 15, and 20 days, significantly reduced COD, TSS, and pH levels. The results showed that both the dosage and detention time had a substantial impact on the effectiveness of Ecoenzyme in treating the waste. The implications of this study suggest that Eco Enzymes can be an effective, eco-friendly solution for improving wastewater management in the tofu industry, thereby contributing to environmental sustainability. [ABSTRACT FROM AUTHOR]

Due to the production of huge quantity of potentially toxic and recalcitrant pollutants, which cannot be completely decomposed with conventional biological wastewater treatment processes, in the paper industry, reliable treatment processes are highly required. This study conducted effective experiments of different series of processes to decompose persistent contaminants in the paper wastewater under controlled conditions of the used processes to meet the effluent quality standards of Korea Ministry of Environment in terms of CODMn (< 130 mg/L). For Biological treatment, Fenton, and photo-Fenton processes, various operational parameters were adjusted to determine the optimal conditions for CODMn value. Due to large quantity of refractory contaminants in the wastewater, single treatment process was not enough to meet the requirement of CODMn. Herein, we achieved the goal with two approaches: (1) secondary Fenton oxidation after biological and primary Fenton treatments, and (2) photo-Fenton treatment after biological treatment alone. The secondary Fenton oxidation process is an additional process operated under the same condition of the primary Fenton treatment to treat the effluent from the primary Fenton treatment. Ultimately, the residual CODMn concentrations of the secondary Fenton and single photo-Fenton treatment were 62.7 and 85.3 mg/L, respectively. However, the secondary Fenton required larger amounts of reagents and produced significant amounts of sludge, which require post-treatment, compared to single photo-Fenton treatment. Therefore, it suggests that the application of photo-Fenton was more efficient than the secondary Fenton in terms of economic feasibility and post-treatment requirement.

The current investigation explores biogas production from water hyacinth (WH) and fish waste (FW) with cow dung (CD) as an inoculum source in two scenarios. In the first scenario, the optimization of mono-digestion was performed where the effect of WH/FW (substrates) with CD (inoculum) in varied ratios of 1:1, 1:2, 2:1, and 3:1 was observed to enhance the biogas production. In the second scenario, the optimization of co-digestion using both FW and WH as substrates in different ratios (1:1, 1:2, and 2:1) with a fixed amount of inoculum was studied. The experiments were conducted in 500 mL digesters in duplicate under mesophilic conditions. Under mono-digestion conditions for FW, the digester operating with FW/CD in a 1:2 ratio demonstrated the highest biogas yield of 970 ± 14.1 mL/g VS, containing 610 CH4 mL/g VS, while in WH, the WH/CD ratio of 1:1 exhibited the highest biogas yield of 925 ± 49.4 mL/g VS, with a methane content of 440 CH4 mL/g VS. The co-digestion of the WH/FW ratio (1:1) showcased the highest biogas production of 1655 ± 91.92 mL/g VS, accompanied by 890 ± 70.7 CH4 mL/g VS. This was followed by the 1:2 and 2:1 ratio, yielding 1400 ± 56.5 and 1140 ± 169.7 mL/g VS. of biogas and 775 and 585 CH4 mL/g VS, respectively. The CD and WH mixture at a 1:1 ratio demonstrated the most significant decrease in chemical oxygen demand (COD), reaching 91.68%. COD reductions over 80% in all combinations were observed in all instances. Anaerobic digestion (AD) simulations were validated using the Gompertz model, with high correlation coefficient values (R-squared) above 0.99 for all of the studied ratios, depicting a significant correlation between experimental data and model predictions. The propionic to acetic acid ratio did not cross the threshold level, indicating no inhibition of methane production. ANOVA analysis of biogas production between the co-digestion and mono-digestion of substrates showed non-significant results (p > 0.310 and p > 0.824, respectively), while overall digestion was significant (p < 0.024), indicating efficiency variations among substrates. Paired sample t-tests revealed substantial differences between co-digestion ratios, which were also significant.

The degradation of recalcitrant organic pollutants by sulphate radical (SO4•−) represents one of the most recent developments in oxidation-based water treatment. In most cases, persulfate (PS) acts as a precursor of sulphate radicals. This study employed ultrasound-activated PS to generate reactive species, facilitating the degradation of bisphenol S (BPS), a well-known contaminant of emerging concern (CECs). An ultrasound with a frequency of 620 kHz and 80 W power was utilised for the degradation studies. The applied oxidation system successfully resulted in the complete degradation of BPS in both pure and real environmental water samples. Additionally, the Chemical oxygen demand (COD) was reduced to an acceptable limit in both matrices, with a reduction of 85 % in pure water and 73 % in river water. The degradation was monitored by varying chemical parameters such as pH, inorganic ions, and organics concentration. The results indicate that under specific pH conditions, the degradation efficiency followed the order of pH 3 > 4 > 7 > 11. The presence of coexisting matrices suppressed the efficiency by scavenging the reactive species. Utilizing high-resolution mass spectrometry (HRMS) analysis, this study identified seven intermediate products during identified during the degradation of BPS. Furthermore, a comprehensive mechanism has been deduced for the transformation and degradation process. All the results presented in this study underscore the applicability of the US/PS system in the removal of CECs.

Wastewater from the production of meat and bone meal, due to the high load of organic matter and suspended solids, is a significant problem in the process of its treatment. In this work, we examined the method of treating this wastewater using coagulation with hydrogen peroxide and the Fenton process. Treatment variants included the use of variable Fe2+/H2O2 ratios of 1:5–1:30, variable doses of 3–18.0 g/L H2O2, and 5–10 mL/L of coagulant PIX 113. The calculated reduction degrees showed that, regardless of the treatment variant used, the greatest reduction was obtained for turbidity (100%), phosphorus (99%), followed by color (97%), chemical oxygen demand (70%), and Kjeldahl nitrogen (48%). The proposed treatment options can be used as a preliminary stage in treating wastewater from the production of meat and bone meal.

In this study, the zero-valent iron Fenton reagent (ZVI Fenton-like) system was combined with the chemical precipitation method for the deep treatment of desulfurization wastewater from coal-fired power plants, and the chemical oxygen demand (COD) was used as the evaluation criterion for organic matter in the desulfurization wastewater. The effects of reaction time, H2O2 dosage, zero-valent iron dosage, pH, and reaction temperature were also investigated. The results showed that the COD concentration of the effluent was the lowest when the running time of the ZVI Fenton-like reagent system was 1 h, the dosage of H2O2 was 33.3 mg·L−1, the dosage of iron was 0.075 g·L−1, the pH was 4.5~6.5, the reaction temperature was 35 °C, the COD concentration of the wastewater was the lowest and its operating conditions were the best, and the internal reaction mechanism was finally deduced. In summary, the zero-valent iron Fenton reagent system provides a new idea for the treatment of desulfurization wastewater from coal-fired power plants.

Poultry slaughterhouse wastewater (PSW) is laden with fats, oil, and grease (FOG), as well as proteins. As such, PSW promotes the proliferation of filamentous organisms, which cause foam formation. In this study, the production of biological defoamers (biodefoamers) uses a consortium with antagonistic properties, i.e., 1.39 L of wastewater/mL defoamers, as reported in our previous study, toward foam formers and their application in the treatment of PSW using a bench-scale activated sludge (AS)-supported treatment system consisting of an aeration and clarification tank. The foam produced was slimy, brown, and thick, suggesting the presence of Nocardia, Microthrix, and Type 1863 species in the PSW/AS wastewater treatment system. The bio (Bio-AS) and synthetic-defoamers (Syn-AS, positive control) supplementation, i.e., at 4% v/v in the PSW/AS primary treatment stage (aeration tank) operated over ten days, resulted in 94% and 98% FOG and protein removal for the biodefoamers, respectively, when compared to 50% and 92% for a synthetic defoamer, respectively. Similarly, the Bio-AS treatment achieved 85.4% COD removal, while a lowly 51% was observed for the Syn-AS PSW treatment regime. Overall, the biodefoamers performed vehemently compared to synthetic defoamers, improving the PSW/AS system’s performance. It was prudent to hypothesize that the biodefoamers might have had FOG solubilization attributes, an assertion that needs further research in future studies. It was concluded that Bio-AS was more efficient in the removal of FOG, proteins, TSS, and COD in comparison to Syn-AS and negative control without supplementation (CAS).

The fluoroquinolone-type antibiotic ofloxacin is regularly detected in wastewaters. In this work, its hydroxyl radical (•OH) induced degradation was studied at a concentration of 0.1 mmol dm−3 in three water matrices, pure water, tap water, and purified wastewater (collected from a wastewater treatment plant). •OH was produced by γ-irradiation under conditions when it had a high yield. The •OH dosage dependencies of chemical (COD) and biochemical (BOD) oxygen demands, total organic carbon (TOC) content, oxygen uptake rate (OUR), Microtox® toxicity, and antibacterial activity values were evaluated. •OH effectively oxidized and mineralized ofloxacin; both processes were observed even at the lowest •OH dosage, 0.14 mmol dm−3 (0.5 kGy absorbed dose). When 0.28 mmol dm−3 •OH was introduced into pure or tap water, the antibacterial activity vanished. In purified wastewater, a higher dosage (0.56 mmol dm−3) was required to achieve the same effect as in pure water, due to the organic molecules of the matrix that quenched the •OH radicals. The products did not have antibacterial activity and showed little toxicity toward the test organism Vibrio fischeri. •OH preferentially attacks the pharmacophore part, the 4-quinolone unit of ofloxacin. •OH-induced reactions can be safely applied to destroy the antimicrobial potency of fluoroquinolone-type antibiotics in purified wastewater matrices.

Water resources are depleting, and the availability and supply of clean, potable water are a global concern. Advanced oxidation processes (AOPs) possess immense prospects in water and wastewater treatment settings. This study investigated and optimized the photocatalytic treatment of wastewater using titanium dioxide (TiO2) as the photocatalyst. The one-factor-at-a-time (OFAT) technique was employed to evaluate the effects of reaction time (20–100 min), mixing speed (20–100 rpm), and catalyst load (0.3–1.5 g/L) on pH, colour, turbidity, and chemical oxygen demand (COD) removal from actual municipal wastewater. Reaction time and catalyst load were then identified as the two key factors selected to be modeled and were optimized for turbidity and COD removal using the Central Composite Design (CCD) of response surface methodology (RSM). These statistical models were developed and used to optimize the operating conditions. The results obtained showed a desirability efficiency of 74.7% at a 95% confidence level. The RSM model predicted results at the optimum conditions and showed reasonable agreement with the experimental results obtained. The optimal responses achieved were 32.64% COD removal and 95.17% turbidity removal. A comparative study between UV light and visible light was also conducted at optimum conditions, whereby the UV light was demonstrated to be highly effective for turbidity and COD removal. The optimal responses achieved were 25.58% COD removal and 66.88% turbidity removal for visible light.

The influence of ultrasound cavitation in the atmosphere of different gases, namely oxygen, air, and nitrogen, on the destruction of impurities of butanol and ethanol found in wastewater from the pharmaceutical plant “Galichpharm” was investigated. The effect of the corresponding gases (oxygen, nitrogen, and air) without ultrasound cavitation on the destruction of ethanol and butanol impurities in wastewater was comparatively investigated. The degree of oxidation of organic matter, effective rate constants, and approximation coefficients were calculated. It was found that the air supply is the least effective for both ethanol and butanol impurities. Degradation of ethanol by air contributed to the reduction in the organic matter content by 14.6 %, while oxidation of butanol was not observed. Ultrasound cavitation enhanced the effect of air and in common action with air the ethanol impurity content reduced by 32.58 %, and butanol impurity by 4.05 %. Nitrogen bubbling produced mediocre results for the destruction of ethanol and butanol impurities giving a decrease by 17.04 % and 0.67 %, respectively. The highest results were obtained with oxygen. Ethanol impurities decreased by 22.47 % and butanol impurities by 1.75 %. With the common action of oxygen and ultrasound, much higher results were obtained, 44.32 % for ethanol impurities and 7.43 % for butanol impurities.

Wastewater of sugar industries has a high pollutant load due to the presence of organic and inorganic materials. Discharge of untreated or partially treated wastewater has a negative effect on the environment and on the life of humans, plants and animals. In our present studies, it was attempted to treat sugar industry effluent (SIE) by an electrocoagulation process (ECP) using mild steel (MS) as the electrode material. For this purpose, three process parameters, namely pH (5–9), current density (j = 34.7–104 A m-2) and treatment time (tR = 20–100 min), were selected to optimize the process using the response surface methodology (RSM). The optimum conditions were pH 6.66, j = = 104 A m-2 and tR = 100 min. The maximum chemical oxygen demand (COD) removal of 75.98 % was achieved under the optimum conditions. The predicted model by RSM showed R2 = 0.9515. After treatment of the effluent, the sludge content in the treated water was separated effectively by filtration and settling.

Wastewater treatment by adsorption onto activated carbon is effective because it has a variety of benefits. In this work, activated carbon prepared from rice husk by chemical activation using zinc chloride was utilized to reduce chemical oxygen demand from wastewater. The as-prepared activated carbon was characterized by scanning electron microscope, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The optimum conditions for maximum removal were achieved by studying the impact of various factors such as solution pH, sorbent dose, shaking time and temperature in batch mode. The results displayed that the optimum sorption conditions were achieved at pH of 3.0, sorbent dose of 0.1 g L−1, shaking time of 100 min and at room temperature (25 °C). Based on the effect of temperature, the adsorption process is exothermic in nature. The results also implied that the isothermal data might be exceedingly elucidated by the Langmuir model. The maximum removal of chemical oxygen demand by the activated carbon was 45.9 mg g−1. The kinetic studies showed that the adsorption process follows a pseudo-first order model. The findings suggested that activated carbon from rice husk may be used as inexpensive substitutes for commercial activated carbon in the treatment of wastewater for the removal of chemical oxygen demand.

This study reports the removal of hydrocarbon (HC) pollutants from petroleum refinery wastewater by integrated photocatalytic oxidation and adsorption using a TiO2/AC hybrid material. The hybrid adsorbent/catalyst was prepared by the impregnation of TiO2 over AC and characterized by FTIR, SEM, EDX, and XRD analyses. Under the optimized reaction conditions of pH 3, 30 °C, and 1000 mg TiO2/AC per 500 mL of sample in 50 min, the integrated photocatalytic oxidation-adsorption achieved a net percentage removal of benzene, toluene, aniline, and naphthalene of 91% from model HC solutions. Under these conditions, for the treatment of real refinery wastewater, TiO2/AC caused a 95% decrease in chemical oxygen demand (COD). The integrated photocatalytic oxidation and adsorption using TiO2/AC showed a clear advantage over the individual adsorption and photocatalytic oxidation using AC and TiO2, whereby about the same level of removal of model HCs and a decrease in the COD of refinery wastewater was attained in 105 min and 90 min, respectively, utilizing larger adsorbent/catalyst dosages. GC-MS analysis revealed that during the integrated process of adsorption-photocatalytic oxidation, all the parent HCs and oxidation byproducts were completely removed from the refinery wastewater. Based on the outstanding performance, cost-effectiveness, and environmental greenness, the newly designed TiO2/AC via the integrated adsorption-photocatalytic oxidation can be counted as an effective alternative route for the large-scale processing of refinery wastewater.

In this study, decolorization of wastewater samples taken from the paper industry is investigated using electrochemical peroxidation process. The electrochemical peroxidation process is a part of electrochemical advanced oxidation processes, which is based on the Fenton’s chemical reaction, provided by addition of external H2O2 into reaction cell. In this study, iron is used as anode and graphite as cathode put at the fixed distance of 30 mm in a glass reaction cell. The cell was filled with the solution containing wastewater and sodium chloride as the supporting electrolyte. Factors of the process such as pH, current intensity, hydrogen peroxide concentration, and time of treatment were studied. The results illustrate that all these parameters affect efficiencies of dye removal and chemical oxygen demand (COD) reducing. The maximal removal of wastewater contaminants was achieved under acid (pH 3) condition, with the applied current of 1 A, and hydrogen peroxide concentration of 0.033 M. At these conditions, decolorization process efficiency reached 100 and 83 % of COD removal after 40 minutes of wastewater sample treatment. In addition, the electrical energy consumption for wastewater treatment by electrochemical peroxidation is calculated, showing increase as the current intensity of treatment process was increased. The obtained results suggest that electrochemical peroxidation process can be used for removing dye compounds and chemical oxygen demand (COD) from industrial wastewaters with high removal efficiency.

2-picoline is a very important pyridine derivative with significant applications though it is also poisonous and harmful having considerable adverse influence on aquatic life, environment and organisms. The need for developing effective treatment methodologies for 2-Picoline directed the current work focusing on degradation of 2-Picoline using the combination of ultrasound and advanced oxidants such as hydrogen peroxide (H2O2), potassium persulphate (KPS), Fenton’s reagent, and Peroxymonosulphate (PMS) along with the use of Titanium oxide (TiO2) as catalyst. Ultrasonic bath having 8 L capacity and operating frequency of 40 ± 2 kHz has been used. The effect of parameters like power, initial pH, temperature, time and initial concentration of 2-Picoline were studied to establish best operating conditions which were further used in the combination treatment approaches of ultrasound with oxidising agents. The chemical oxygen demand (COD) reduction for the optimized approaches of ultrasound in combination with oxidizing agents was also determined. Degradation experiments were performed using oxidising agents also in absence of ultrasound to investigate the individual treatment capacity of the oxidants and also the synergetic index for the combination. Kinetic study demonstrated that second order model suited for all the treatment approaches except US/Fenton where first order model fitted better. Ultrasound in combination with Fenton reagent demonstrated a substantial synergy for the degradation of 2-Picoline compared to other treatment approaches showing highest degradation of 97.6 %, synergetic index as 5.71, cavitational yield of 1.82 × 10−5 mg/J and COD removal of 82.4 %.

The limitations of TiO2 as a photocatalyst such as the larger bandgap energy, which only activates under the UV region, give a lower photocatalytic activity. This study reports the role of the N and Pt co-dopant on the modification of the TiO2 photocatalyst for photocatalytic degradation of methylene blue dye under different mode preparations, i.e., sequential and vice-versa modes. The sequential mode preparation of the N and Pt co-dopant TiO2 photocatalyst consisted of the initial preparation of the N-doped TiO2 (N-TiO2) under the calcination method, which was then further doped with platinum (Pt) through the photodeposition process labeled as NPseq-TiO2, while the vice-versa mode was labeled as PNrev-TiO2. About 1.58 wt.% of N element was found in the NPseq-TiO2 photocatalyst, while there was no presence of N element detected in PNrev-TiO2, confirmed through an elemental analyzer (CHNS-O) and (EDX) analysis. The optimum weight percentage of Pt for both modes was detected at about ±2.0 wt.%, which was confirmed by inductively coupled plasma-emission spectroscopy (ICP-OES). The photoactivity under methylene blue (MB) dye degradation of the NPseq-TiO2 photocatalyst was 2 and 1.5 times faster compared to the unmodified TiO2 and PNrev-TiO2, where the photodegradation rates were, ca., 0.065 min−1 and 0.078 min−1, respectively. This was due to the N elements being incorporated with the TiO2 lattice, which was proven by UV-Vis/DRS where the bandgap energy of NPseq-TiO2 was reduced from 3.2 eV to 2.9 eV. In addition, the N generated a stronger PL signal due to the formation of oxygen vacancies defects on the surface of the NPseq-TiO2 photocatalyst. The higher specific surface area as well as higher pore volume for the NPseq-TiO2 photocatalyst enhanced its photocatalytic activity. Moreover, the NPseq-TiO2 showed the lowest COD value, and it was completely mineralized after 7 h of light irradiation. The preparation order did not affect the Pt dopant but did for the N element. Therefore, it is significant to investigate different mode preparations of the N and Pt co-dopant for the modification of TiO2 to produce a good-quality photocatalyst for photocatalytic study under the photodegradation of MB dye.

Agro-waste management processes are evolving through the development of novel experimental approaches to understand the mechanisms in reducing their pollution levels efficiently and economically from industrial effluents. Agro-industrial effluent (AIE) from biorefineries that contain high concentrations of COD and color are discharged into the ecosystem. Thus, the AIE from these biorefineries requires treatment prior to discharge. Therefore, the effectiveness of a continuous flow bioreactor system (CFBS) in the treatment of AIE using hybrid waste sludge biochar (HWSB) was investigated. The use of a bioreactor with hydraulic retention time (HRT) of 1–3 days and AIE concentrations of 10–50% was used in experiments based on a statistical design. AIE concentration and HRT were optimized using response surface methodology (RSM) as the process variables. The performance of CFBS was analyzed in terms of COD and color removal. Findings indicated 76.52% and 66.97% reduction in COD and color, respectively. During biokinetic studies, the modified Stover models were found to be perfectly suited for the observed measurements with R2 values 0.9741 attained for COD. Maximum contaminants elimination was attained at 30% AIE and 2-day HRT. Thus, this study proves that the HWSB made from biomass waste can potentially help preserve nonrenewable resources and promote zero-waste attainment and principles of circular economy.

Excess levels of organic and inorganic matters in the discharge from sugarcane mill effluent (SCME) wastewater, causes the earnest environmental issue. In this study, a single unit integrated ultrasonic membrane anaerobic system (IUMAS) has been investigated for industrial sugarcane wastewater treatment. As the “Membrane-fouling” is one of the main constraints of IUMAS which eventually reduce the processing ability. In the present study, most researchers resort to cost reduction. IUMAS was alternatively applied as an economical approach for SCME wastewater treatment. The application of “Multiple-analysis” methods (COD, BOD, TSS) and three kinetic models during the treatment, suggested the specific range of organic loading rate to produce biogas. The result showed the increased methane gas production up to 80% in the biogas, with 94 -96% of COD removal efficiency from the SCME wastewater. Results concluded the effective efficiency of IUMAS to reduce the membrane fouling and treatment of SCME wastewater as well as enhanced production of methane gas.

Visible light responsive Graphene oxide (GO) nanotitania composite was synthesized and its photocatalytic activity was investigated for the degradation of Eosin Yellow (EY). The nanocomposite was synthesized by organic solvent free-controlled hydrolysis of titanium tetrachloride (TiCl4) exfoliated with 10 wt. % (0.5 g) of the as prepared GO particles under ultrasonication through in-situ addition of the aqueous GO solution. The synthesized nanocomposite has been characterized using X-Ray Diffraction (XRD), UV-Visible Diffuse Reflectance Spectral (UV-Vis DRS) and Field emission scanning electron microscope (FESEM) techniques. In the presence of visible light, its photocatalytic activity was enhanced on contrast with the synthesized bare nanotitania particles. The aqueous solution of EY has degraded in 80 minutes (95.5 %). It was also supported with the increase in the rate constant with the composite (7.05 x 10-2 min-1) as compared with that of the nanotitania (1.41 x 10-2 min-1). Through the chemical oxygen demand (COD) studies, effective mineralization of the dye was observed with the nanocomposite.

The performance of Picralima nitida extract (PNE) in bio-coagulation-flocculation (BCF) for the reduction of chemical oxygen demand (COD) in municipal solid waste leachate (MSWL) was studied. The PNE was characterised via Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). The process was modelled using both the response surface methodology (RSM) and artificial neural network (ANN) methods, and their prognostic capabilities established. The coagulant precursor was found to contain protein (28.4%) which is an active component of a good coagulant for neutralisation and adsorption of the colloidal particles. C=O, O–H, and N-H functional groups were present in the extract which are preferred for BCF process. This process was effectively optimised (COD ​= ​75.25 ​± ​0.5%) to achieve the best removal at pH ​= ​2.3, PNE dosage ​= ​0.38 ​g/L, and time ​= ​28.22. min. The analysis of variance indicated that the RSM model was statistically suitable for the interpretation of the processes at the studied range. The RSM and ANN were capable of predicting the COD reduction process with the latter giving the best prediction with lesser error and nonlinear relationship. Though ANN had superior accuracy, RSM has the advantage of giving a predictive equation and showing the effect of operating factors and their interactions on the response compared. The mechanisms of the process were charge neutralisation, adsorption and bridging.

Waste-activated sludge (WAS) disintegration using peroxydisulfate (PDS) has attracted scientific attention over the past few years. Despite several advantages offered by a sulfate radical-advanced oxidation process, there are still too many downsides of this treatment that limit its facile large-scale application. This study investigated whether modifying nano zero-valent iron (nZVI) with a second metal such as Ag and Cu enhanced the disruption of WAS. The disintegration efficiency was assessed using standard techniques, i.e., soluble chemical oxygen demand, Fourier-transform infrared spectroscopy and a scanning electron microscope. The bimetallics were shown to have an improved disintegration efficiency of > 2.5-fold compared with the untreated sample. Furthermore, nZVI/Ag was found to be more efficient than nZVI/Cu for PDS activation, which was validated by the higher ratio (3 and 2.5 for nZVI/Ag and nZVI/Cu, respectively) between the soluble extracellular polymeric substances and the bound extracellular polymeric substances (S-EPS/B-EPS). Similar conclusions were derived from a SEM analysis. The improved disintegration efficiency could be related to the enhanced electron transfer from nZVI to PDS or the intrinsic properties of silver, which was found to be one of the best activators for PDS under homogeneous conditions. We believe that this study deepens the understanding of PDS heterogeneous activation processes.

TiO2 develops a higher efficiency when doping Bi into it by increasing the visible light absorption and inhibiting the recombination of photogenerated charges. Herein, a highly efficient Bi doped TiO2 photoanode was fabricated via a one-step modified sol-gel method and a screen-printing technique for the anode of photocatalytic fuel cell (PFC). A maximum degradation rate of 91.2% of Rhodamine B (RhB) and of 89% after being repeated 5 times with only 2% lost reflected an enhanced PFC performance and demonstrated an excellent stability under visible-light irradiation. The excellent degradation performance was attributed to the enhanced visible-light response and decreased electron-hole recombination rate. Meanwhile, an excellent linear correlation was observed between the efficient photocurrent of PFC and the chemical oxygen demand of solution when RhB is sufficient.

Tofu industry wastewater is one of the environmental pollutants that need more effective treatment. Ozonation and adsorption method is known to have the capability to oxidize organic compound in wastewater. Adsorption is done by using granular activated carbon (GAC) as an adsorbent to increase tofu wastewater degradation process by adsorbing organic materials and increasing production of hydroxyl radical as the main oxidizing agent. This research is carried out to evaluate the performance of ozonation, adsorption, and combination of both in processing tofu wastewater. To evaluate the significance of ozone dosage and amount of GAC used, these variations are varied which are 60, 111, and 155 mg/h of ozone dosage and 50, 75, and 100 g of the amount of GAC used. Parameters of the process are organic substances of tofu wastewater such as COD, TSS, and pH. The measurements are being done using a spectrophotometer, colorimeter, and pH meter. The outcome of this research is to provide an alternative method in the liquid waste treatment of the tofu industry and the processed wastewater to meet the environmental quality standards. The more ozone and the more quantity of GAC used, the higher the quantity of hydroxyl radicals formed. Addition of GAC in the ozonation process results in more than 100% increase in hydroxyl radical production. Combination of ozonation and adsorption is able to remove 377.12 mg/L of COD and 26 mg/L of TSS.

Proton exchange membranes (PEMs) were synthesized using three different compositions of poly(oxyethylene) (POE), poly(vinyl alcohol) (PVA), chitosan (CS) and phosphoric acid (PA) in weight ratios of 1:1:1:1, 1:2:1:1 and 1:3:1:1 by physical blending and the casting method. Water uptake of the membrane increases with increasing concentration of PVA. A higher percentage of water uptake signifies a higher ion exchange capacity (IEC) of the synthesized membrane. The synthesized membranes were evaluated in microbial fuel cells (MFCs) and the performance observed. The synthesized membranes were characterized for identification of precursor material and inter polymer interactions using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis, respectively. The removal of chemical oxygen demand (COD) depends on the microbial activity in the anodic chamber. In the present study, the composition of the membrane was optimized and compared with other membranes that had been synthesized by different compositions of all materials. COD removal in the MFC-3 setup connected with an M-3 membrane was found to be 88 %.

In this study, Zn‐Al, Mg‐Al and Ni‐Al layered double hydroxides were successfully synthesized via co‐precipitation method. Samples were characterized by XRD, FTIR, TGA‐DTA, TEM and pHPZC analysis. XRD patterns showed a basal spacing increase in the order of Zn‐AlNO3 (8.85Å)> Mg‐AlNO3 (7.95Å)> Ni‐AlNO3 (7.82Å). TEM images indicated that the Zn‐AlNO3 presents circular to shaped particles with an average particle size of approximately 30 to 40 nm. Small plates assigned to sheets with hexagonal form were observed in the case of Mg‐AlNO3. Ni‐AlNO3 display nanostructured sphere in diameter between 5 and 10 nm. The materials were used for the removal of methyl orange (MO), as a model dye and for the treatment of a real effluent generated by a textile factory. Maximum adsorption was occurred in acidic pH solution. Kinetic data were tested using pseudo‐first‐order, pseudo‐second‐order kinetic and intra‐particle diffusion models. The best fit was obtained with the pseudo‐second‐order kinetic model. Equilibrium data were correlated to Langmuir, Freundlich, Sips and Redlich–Peterson isotherm models. The best conditions for color and COD removal from the textile effluent sample were obtained at lower values of pH. Reduction of COD to limits authorized by Moroccan standards was obtained with 0.5g/L of LDH dosage.

In this study, a low-cost, efficient, and environmentally friendly anaerobic sludge process for the treatment of industrial beverage wastewater was investigated to analyze the effect of bacteria growth on the degradation of organic matter (chemical oxygen demand). Additionally, the mechanism, interactions between the microbe’s growth, and operating conditions of an anaerobic batch reactor along with the wastewater treatment efficiency were evaluated via microbial kinetics. The kinetic coefficients based on chemical oxygen demand (COD) by conventional techniques such as kinetic coefficients growth yield (0.46 mg VSS/mg COD), saturation coefficient (3500 mg/L COD), the maximum rate of substrate utilization per unit mass of biomass (0.0066 mg/L COD), growth rate by Monod equation, M (0.03833 L/h), and maximum growth rate, μm (0.03672 L/h) were calculated. The results show a higher rate of substrate degradation (0.54 day−1) due to the high COD removal efficiency (CRE) of 99.31% during 13 days that was achieved, which can be attributed to the active involvement of anaerobic microbes in the process of degradation. Based on these results, it can be concluded that the current study can be used as an effective way to analyze the industrial beverage wastewater at commercial levels.

Organic materials in fresh-cut produce wash water deplete free chlorine that is required to prevent pathogen survival and cross-contamination. This research evaluated water quality parameters frequently used to describe organic load for their fitness to predict chlorine demand (CLD) and chemical oxygen demand (COD), which are major needs identified by the industry-led produce food safety taskforce. Batches of romaine lettuce, iceberg lettuce, or carrot of different cut sizes and shapes were washed in 40 liters of water. Physicochemical properties of wash water including CLD, COD, total organic carbon (TOC), total suspended solids (TSS), total dissolved solids (TDS), turbidity, total sugar content, and pH, were monitored. Results indicate that pH is primarily commodity dependent, while organic load is additionally impacted by cutting and washing conditions. Significant linear increases in COD, TOC, CLD, TDS, and turbidity resulted from increasing product-to-water ratio, and decreasing cut size. Physicochemical parameters, excluding pH, showed significant positive correlation across different cut sizes within a commodity. High correlations were obtained between CLD and COD and between COD and TOC for pooled products. The convenient measurement of TDS, along with its strong correlation with COD and CLD, suggests the potential of TDS for predicting organic load and chlorine reactivity. Finally, the potential application and limitation of the proposed models in practical produce processing procedures are discussed extensively. [ABSTRACT FROM AUTHOR]

Sustainable management of leachate produced from the dumpsite is one of the major concerns in developing countries Aquatic plants such as duckweed have the potential to remove pollutants from wastewater which can also be cost-effective and feasible options for leachate treatment. Therefore, the objective of our present study was to examine the growth and nutrient removal efficiency of duckweed (Lemna minor) on leachate. Three tests were performed each by growing lemna minor on synthetic leachate under controlled conditions and on dumpsite leachate under natural conditions. During each test, duckweed was grown in 300 ml plastic containers with a surface area of 25.8 cm2. About 60 mg of fresh mass of duckweed was grown on 250 ml leachate at an internal depth of 9.5 cm. Results revealed that, in comparison to synthetic leachate, duckweed removed Chemical Oxygen Demand (COD), nitrogen (N), and phosphorous (P) more efficiently from dumpsite leachate under natural climatic conditions. However, the amounts of N and P absorbed into duckweed body mass were about 16% and 35% respectively more at synthetic leachate under controlled conditions. Maximum growth rate of duckweed (7.03 g m-2 day-1) was also observed for synthetic leachate in comparison to the growth rate of 4.87 g m-2 day-1 at dumpsite leachate. Results of this study provide a useful interpretation of duckweed growth and nutrient removal dynamics from leachate under natural and laboratory conditions. [ABSTRACT FROM AUTHOR]

Ganga, a river of global significance, is under increasing pressure from excessive release of carbon and nutrients. We conducted the first detailed watershed-scale study to assess water quality status and possible drivers in different segments of the Ganga River. For this, we analyzed 24 water quality variables from March 2016 to February 2018, at 7 study sites, along a 2320-km river stretch. The data revealed large spatiotemporal variations in total dissolved solids, major ions, nutrients, dissolved organic carbon, biological oxygen demand (BOD), chemical oxygen demand, chlorophyll a biomass (Chl a) and gross primary productivity. Principal component analysis identified three major determinants (source input, stream flow, and tidal influence) explaining over 84% of the total variance. A high concentration of oxygen-demanding chemicals, especially in the middle segment, underscores the importance of restoration efforts that address BOD reduction alone. This work advances our understanding with respect to inter-segment variations and factors regulating Ganga River water quality and demonstrates the significance of watershed-scale studies for integrated river basin management. [ABSTRACT FROM AUTHOR]

Water conservation and economics dictate that fresh produce processors reuse/recirculate the process water. However, the ensuing accumulation of organic matter in water depletes the chlorine sanitizer required for food safety. In this study, we comprehensively investigated chemical compounds that are responsible for water quality in relation to chemical oxygen demand (COD) and chlorine demand (CLD), the two most critical factors associated with water treatment and chlorine replenishment. Simulating commercial fresh-cut wash operations, multiple batches of diced cabbage (0.3 x 0.3 cm2) were washed in the same tank of water. The major components were isolated from the wash water and analyzed by HPLC. Sugars were the predominant compounds (82.7% dry weight) and the major contributor to COD (81.6%), followed by proteins/peptides (7.3% dry weight, 5.3% COD), organic acids (6.2% dry weight, 3.6% COD), and phenolics (0.5% dry weight, 0.5% COD). By repeated time course measures, the effect of these chemicals on CLD are dependent on the chemical structure, concentration in the wash water, and their rate of reaction. Proteins/peptides accounted for about 50% of the total CLD over a 120-min period and phenolics was 21% at 5 min, but diminished with time. The contribution by organic acids and sugars increased continuously, reaching 22% and 16% of total CLD at 120 min of chlorination, respectively. Collectively, these compounds represented 86% of the CLD in cabbage wash water at 5 min and greater than 94% CLD afterwards. This is the first systematic report on the source of COD and CLD during fresh produce washing. It provides essential information for the produce processors to develop safe, effective, and economical wash water treatment/reuse and chlorine replenishment strategies. [ABSTRACT FROM AUTHOR]