pH Of Wastewater Research Articles

Machine learning-assisted prediction of engineered carbon systems' capacity to treat textile dyeing wastewater via adsorption technology.

Dyes are widely used in industries like printing, cosmetics, paper, leather processing, textiles, and manufacturing to add color to products. However, improper disposal of dyes into wastewater has raised major concerns due to their harmful effects on plants, animals, and humans. Using engineered carbon systems (ECSs) to treat dye-contaminated wastewater has shown promise for sustainable waste management. Dye adsorption on ECSs is a complex, non-linear process, making it essential to understand ECSs' dye removal capabilities through a modeling framework that includes experimental and environmental factors. To support this, a database of ECSs used in dye removal from textile wastewater was compiled. Twelve machine learning models, including XGBoost, Light Gradient Boost, Random Forest, Gradient Boost, CatBoost, AdaBoost, Decision Tree, Artificial Neural Network, K-Nearest Neighbor, Support Vector Machine, Huber, and Ridge Regressor, were applied to analyze ECSs' dye removal potential. Out of all the models, XGBoost exhibited the highest coefficient of determination (R2) of 0.986 during the training and 0.978 during testing, alongside the lowest prediction error (MSE) of 0.01 and 0.136 in the training phase and testing phase. The quantity of ECS, concentration of dye (Co), and pH of wastewater highly influenced the adsorption process. The optimization results indicated the highest affinity of direct, reactive, and dispersed dyes towards ECSs in the acidic solution. In contrast, the maximum adsorption of Basic and VAT dye on ECSs was found in the alkaline solution. The partial dependence analysis provided valuable insights into the interaction between ECS dose and water matrix parameters that can lead to efficient extraction of dyes from aqueous matrices.

The Electrocoagulation Method for Removing Zinc and Chromium from Electroplating Industry Wastewater

Wastewater from electroplating is often found to contain heavy metals. This study used the electrocoagulation (EC) method with iron (Fe) electrodes to remove two heavy elements (Cr and Zn) from actual electroplating effluent at the same time. The effect of EC time and wastewater pH on removal performance was investigated. It was determined that optimum Cr and Zn removal occurred at a pH of 9 and after 30 minutes. It was discovered that the clearance rates for Zn and Cr were 79% and 99%, respectively. The elimination of these heavy metal ions was compatible with a pseudo-first-order model, according to kinetic investigations. The removal of electroplating wastewater by the EC method occurs with low energy consumption, making the process economically viable and scalable. In the EC experiments using Fe electrodes, the electrode consumption was found to be 1.07 kg/m³, and the energy consumed was 25 kWh/m³.

The effectiveness of ozonation treatment in reducing ph, turbidity, bod, cod, and toc in pharmaceutical industrial wastewater

Abstract The pharmaceutical industry’s fabrication of pharmaceutical products releases byproducts that have the potential to negatively impact the environment. Indicators of contaminants include characteristics such as COD, BOD, TOC, pH, and turbidity that are within acceptable standards of excellence. The objective of this study was to look at fluctuations in the concentrations of pharmaceutical wastewater substances parameters before and following treatment with the ozonation method, as well as to assess the ozonation procedure’s performance on pharmaceutical wastewater contaminants parameters. The ozonation methods, which altered the O3 retention period, served as the independent variable in this study. The dependent variables applied were pH optimalization, and the removal efficiency of turbidity, BOD, COD, and TOC. Controlling variables involve the starting pollutant concentration, pressure and temperature levels, and equipment conditions. To determine the ideal time variation for the ozonation process, many variations will be evaluated. However, several parameters (e.g. pH, BOD, and TOC) were not reducing with the designed time variations. Nevertheless, this approach was effective in reducing turbidity levels by 48.5% and COD levels by 55.4% over 15 minutes.

Efficient and sustainable approach of heavy metal adsorption from wastewater using algal biomass of Hypnea valentiae (Turner) Montagne, 1841

The biosorption of heavy metals especially, Cd2+, Pb2+, and Zn2+ from wastewater were evaluated using the biomass of macroalgae, Hypnea valentiae found in coastal waters of Rameshwaram, Tamil Nadu, India. The probable functional groups involved in the biosorption process was analyzed by Fourier transform infrared spectroscopy. The specific surface area, pore volume and pore diameter of prepared biosorbent was determined by Brunauer–Emmett–Teller (BET) analysis and it was found to be 59.993 m2 g−1, 0.292 cc g−1 and 1.429 nm, respectively. The scanning electron microscopy images after the biosorption revealed that the heavy metals have been adsorbed on to the surface of biosorbent. The optimization study was performed using Box–Behnken design and the optimum parameters used were initial concentration of metal ions (10–500 mg L−1), biomass dose (5–25 g L−1), contact time (10–120 min), temperature (25–45 °C), agitation speed (60–120 rpm) and pH (2–14). The heavy metal uptake (biosorption) was assessed by isotherm models including Dubinin–Radushkevich (D–R), Freundlich and Langmuir models. The maximum sorption of metal ions was observed in Langmuir isotherm model (R L 0.1773 and K F 2.2030 L mg−1) with an R 2 value close to 0.99 clearly indicating the chemical mode of metal ion adsorption. Also, the sorption of Cd2+, Pb2+, and Zn2+ on to the surface of algal biomass followed pseudo-second-order kinetics with a rate constant, k2 being 9.627 × 10−3 g (mg min) −1 and qe being 93.98496 mg g−1, strongly supporting the chemisorption mechanism. The computed thermodynamic parameters (ΔG°, ΔH, and ΔS) demonstrated an endothermic, spontaneous biosorption that was feasible. The maximum removal efficiency was achieved for Pb (92.86%) followed by Cd (91.48%) and Zn (87.32%). The biosorbent can be reused and regenerated up to four cycles efficiently. There was a significant reduction in the biological oxygen demand, chemical oxygen demand, total dissolved solids, and pH of wastewater after treatment with the biosorbent. From this study, it is assessed that the biomass from red algae can be utilized for the biosorption of heavy metals from polluted water which is cost-effective and eco-friendly.

Comparison of Machine Learning Algorithms for Prediction of Textile Effluent Treatment Efficiency Using Anaerobic Process

ABSTRACTThe prediction of pollutants removal efficiency from the generated effluent of a treatment plant is valuable and can reduce the time, sampling and energy required during performance assessment. The present study aims to predict the effect of different input parameters on the treatment efficiency of the developed microbial‐based anaerobic process for textile effluent using machine leaning algorithms. The decolourisation and chemical oxygen demand (COD) reduction of the treated effluent were predicted on the basis of the three different input parameters pH, COD and colour value of the textile wastewater. The effectiveness of different machine learning algorithms, support vector machines (SVM), random forest (RF), gradient boost regressor (GBR), AdaBoost, extreme gradient boosting (XGB) regressor and voting regressor, were evaluated based on the correlation coefficient (R2) value. The results revealed that the RF achieved the highest accuracy for decolourisation (training data R2: ∼0.85 and test data R2: ∼0.84) as well as COD reduction (training data R2: ∼0.87 and test data R2: ∼0.94) compared to the other algorithms. These results were validated experimentally, confirming that RF can be used as a tool to predict the performance efficiency of a microbial‐based treatment system.

Synergistic low-temperature plasma degradation of tetracycline with ferrocene

Low-temperature plasma technology has been successfully applied to the treatment of persistent organic pollutants in water. By combining catalysts with low-temperature plasma, the degradation efficiency and energy utilization efficiency of pollutants can be effectively improved. In this study, ferrocene (Fc) was added as a new catalyst to the low-temperature plasma system to treat tetracycline (TC) found in wastewater. The degradation efficiency of TC after 60 min of plasma treatment, Fc adsorption, and Fc/plasma treatment was compared, indicating that Fc/plasma improved the removal compared with using plasma alone. The effects of primary parameters such as Fc dosage, initial pH, discharge voltage, and anions in wastewater on TC removal efficiency were investigated. Under the conditions of Fc dosage of 400 mg/L, pH of 9, and discharge voltage of 20 kV, the degradation efficiency of TC was 76.59%. Results of free quenching experiments indicated that hydroxyl radicals played an important role in the treatment of TC. The characterizations of Fc showed that the structure of Fc before and after use in the plasma system changed little. In addition, toxicity testing using toxicity assessment software showed that only two to three degradation intermediate products had slightly higher toxicity than TC. The iron leaching concentration was 2.5 mg/L, and the Fc dissolution concentration was 1.72 mg/L after the reaction.

Mitigating Membrane Fouling in Abattoir Wastewater Treatment: Integration of Pretreatment Step with Zwitterion Modified Graphene Oxide-Polyethersulfone Composite Membranes.

Composite polyethersulfone (PES) membranes containing N-aminoethyl piperazine propane sulfonate (AEPPS)-modified graphene oxide (GO) were integrated with either of the two pretreatment processes (activated carbon (AC) adsorption or polyelectrolyte coagulation) to assess their effectiveness in mitigating membrane fouling during the treatment of abattoir wastewater. The AEPPS@GO-modified membranes, as compared to the pristine PES membranes, showed improved hydrophilicity, with water uptake increasing from 72 to 118%, surface porosity increasing from 2.34 to 27%, and pure water flux (PWF) increasing from 235 to 673 L.m-2h-1. The modified membranes presented improved antifouling properties, with the flux recovery ratio (FRR) increasing from 59.5 to 93.3%. This study compared the effectiveness of the two pretreatment processes, AC, coagulation, and the integrated system (coagulation/AC-UF membrane), in the removal of natural organic matter (NOM) and improvement of abattoir wastewater's pH, electrical conductivity, TDS, and turbidity. The integrated systems produced improved water quality in terms of pH, EC, TDS, turbidity, and organic content. The fluorescence excitation-emission matrix (FEEM) analysis exhibited almost no fluorescence peak post-treatment following organic loading removal. The quality of the water met the South African non-potable water reuse standards. The sole membrane treatment systems exhibited good fouling resistance without the pretreatment systems; however, integrating these systems can offer extended longer filtration periods, thereby assisting in cost aspects of the abattoir wastewater treatment system.

Enhancing biodecolorization of Malachite Green by Flavobacterium sp. through monothetic analysis

Malachite Green (MG) is a prevalent dye in the textile industry, known for its harmful environmental impacts. Addressing the urgent need for environmentally friendly and cost-effective methods to remove MG from wastewater, this study investigated the efficacy of Flavobacterium sp., isolated from Malaysian batik wastewater, in decolorizing MG. Under shaking conditions at 160 rpm, Flavobacterium sp. exhibited a notable decolorization efficiency, with 91 % removal of MG after a 3-day incubation time, surpassing the static mode efficiency of 39 %. Further optimization using a one-factor-at-a-time (OFAT) methodology at 37 °C, pH 10, 6 % (v/v) inoculum, banana peel as the carbon source and 250 mg/L MG resulted in a remarkable enhancement, achieving 95 % decolorization within a reduced incubation time of 12 h. Moreover, repeated addition of 250 mg/L MG showed consistent and complete decolorization after 6 h by Flavobacterium sp. for four successive cycles, suggesting its economic viability for treating actual Malaysian batik wastewater. Ultraviolet–visible (UV) analysis confirmed the biodegradation of MG, evidenced by the disappearance of characteristic peaks at 618 nm and the appearance of new peaks, indicating the formation of metabolites. Flavobacterium sp. reduced pH, temperature, color, TDS, TSS, BOD and COD in batik wastewater, showing 99 % color removal efficiency. This research highlights its potential as an eco-friendly, cost-effective treatment for batik wastewater. The capacity of Flavobacterium sp. to decolorize MG in an immobilized state will be the subject of future research endeavors, aimed at elucidating the adaptability and usefulness of the biocatalyst.

Agro-waste based biomass residues valorization for effective adsorption of heavy metal.

In this experiment four agro-waste based biomass residues (soybean stover-SSb, buckwheat stover-BWb, Artemisia vulgaris- AVb and Chromolaena odorata-COb) was valorized into low cost amendment called biochar followed by compositional characterization for their application in heavy metal removal. Investigation was carried out on the removal of the most common heavy metal ions including arsenic, cadmium, lead, nickel, zinc, and copper through adsorption on four types of biomass valorised biochar. According to preliminary testing, all the biochar was effective to eliminate a mixture of six heavy metals from the aqueous phase, with the removal of arsenic being the most removed and nickel being the least. In comparison to no biochar treatment, the average removal rate of heavy metal from aqueous solution using four distinct types of biochar was 45.75-62.42% (Cd), 43.64-56.33% (Pb), 41.85-59.73% (Ni), 42.87-60.28% (Zn), 45.64-59.51% (Cu), and 49.02-60.53% (As). The percent decrease of cadmium heavy metal adsorption with increase in maximum contaminant level (MCL) from 1- to fivefold was 20.0 (SSb), 20.7 (COb), 21.6 (BWb), and 22.9 (AVb). The results of the dosage study indicated that As adsorption was the most beneficial on all four types of biochar, whereas Ni adsorption was the least effective. With increase in application rate of biochar the heavy metals adsorption (%) was also increased. Four different agro-waste valorized biochar were used to treat the wastewater, and the physical and chemical changes that occurred both before and after the biochar treatment were noted. There was a drop in the wastewater CODT, CODD, TSS, ammonia, TKN, TP and pH values of 79.7-103.5%, 57.7-81.5, 52.3-68.4%, 1.23-2.23%, 14.1-20.6%, and 1.23-3.03%, respectively. Furthermore, after being passed through a biochar, the wastewater's Zn, Pb, Cd, As, Cr and Cu levels decreased by 3.26-6.15%, 0.06-0.34%, 0.01-0.08%, 2.37-3.65%, 3.95-5.53%, and 2.24-3.34%, respectively at 2.5 and 5.0g/litre of wastewater. Thus, in order to comply with regulations for the disposal of wastewater effluent, the process of valorizing biomass into biochar offered enormous potential for the removal of heavy metals in addition to wastewater treatment.

Enhanced Treatment of Antimony Mine Wastewater by Sulfidated Micro Zerovalent Iron (S-mZVI).

Commercial micron zerovalent iron (mZVI) and sulfur were used to prepare sulfidated micro zerovalent iron (S-mZVI) through ball milling. The corrosion potentials of mZVI and S-mZVI were -0.01 and -0.37 V, respectively, indicating S-mZVI possessed a stronger electron-donating ability. The practical antimony mine wastewater (C0(Sb(V)) = 3.8296 mg/L, pH = 8.29) was treated. If meeting the national discharge standard of 5 μg/L, 2.0 g/L mZVI and 1.6 g/L S-mZVI were required within 120 min. Passing N2 or reducing wastewater pH enhanced the treatment of Sb(V) by S-mZVI, in which the wastewater acidification was more effective. Once the wastewater pH was adjusted to 3.00, only 0.7 g/L S-mZVI and 40 min long time were needed to achieve the emission below 5 μg/L. Even S-mZVI underwent four cycles, and the final concentration of Sb(V) was as low as 4.67 μg/L. As the pHzpc value was 4.09 and the corrosion potential was -0.56 V at pH 3.0, the electron-donating ability of S-mZVI as well as the electrostatic attraction between the surface of S-mZVI and Sb(V) increased. Sulfidation of mZVI and then application under the acid condition significantly improved the treatment efficiency of Sb(V).

Heavy metal migration and enrichment in desulfurization wastewater during low-temperature triple effect evaporation process

Zero discharge of desulfurization wastewater from coal-fired power plants has become important. Desulfurization wastewater and gypsum from different stages of the low-temperature triple-effect evaporation process of a coal-fired power plant were collected and investigated. The results showed that after low-temperature triple-effect evaporation, the concentrations of Na+, Mg2+, K+, and Cl− in the desulfurization wastewater increased by 7.91, 7.15, 8.49, and 8.35 times, respectively. With the progress of low-temperature triple effect evaporation process, the concentrations of As, Cd, Co, Cr, Cu, Mn, Se, and Zn in the wastewater after the triple effects were 5.85, 75.44, 1.28, 2.34, 13.66, 5.58, 8.59, and 4.35 times higher than those in the raw wastewater. Mn and Se exceeded the emission limits by 40 and 10 times, respectively. After triple-effect evaporation, the concentrations of As, Cd, Co, Cr, Cu, Pb, Se, and Zn in gypsum decreased to 46%, 26%, 66%, 41%, 35%, 97%, 39%, and 51% of the raw gypsum, respectively. Compared with that of other metal sulfates, the solubility of PbSO4 was extremely low under low-temperature conditions, and some PbSO4 precipitated during the triple-effect evaporation process, leading to a gradual decrease in the Pb concentration in the liquid phase. The mercury compounds in gypsum after the first and second effects were the same as those in raw gypsum, both of which were HgS and HgO. After third effect, the mercury compound in gypsum also included HgSO4. In addition, owing to the promoting effect of the pH of desulfurization wastewater approaching 5.50 on the generation of HgS, the proportion of HgS gradually increased, and the proportion of HgO gradually decreased from the raw gypsum to the third effect gypsum. Therefore, the stability of the mercury compounds in gypsum was enhanced. It can provide a good reference for the migration and enrichment of heavy metals in the low-temperature triple-effect evaporation process, which is beneficial for the clean production and efficient utilization of coal.

Combining Activated Carbon Adsorption and CO2 Carbonation to Treat Fly Ash Washing Wastewater and Recover High-Purity Calcium Carbonate

Fly ash washing wastewater was carbonated with carbon dioxide (CO2) to remove calcium (Ca) by forming a calcium carbonate (CaCO3) precipitate. An investigation of the factors affecting carbonation showed that Ca removal was highly dependent on the initial pH of the wastewater. The Ca removal was 10%, 61%, 91% and more than 99% at initial wastewater pH levels of 11.8, 12.0, 12.5 and 13.0, respectively. The optimal conditions for carbonation were initial pH of 13.0, carbonation time of 30 min and CO2 flow rate of 30 mL/min. The Ca concentration in the wastewater decreased to <40 mg/L, while 73 g of CaCO3 precipitate was produced per liter of wastewater. However, heavy metals, specifically Pb and Zn, co-precipitated during carbonation, which resulted in a CaCO3 product that contained as much as 0.61 wt% of Pb and 0.02 wt% of Zn. Activated carbon modified by a quaternary ammonium salt was used to selectively adsorb the Pb and Zn first. The Pb- and Zn-free water was then carbonated. By combining adsorption with carbonation, the Ca concentration in the treated wastewater was decreased to about 28 mg/L, while the Na, Cl and K were retained. The wastewater thus treated was ready for NaCl and KCl recovery. In addition, the precipitate had a Ca content of more than 38 wt% and almost no heavy metals. The average particle size of the precipitate was 47 μm, with a uniform cubic shape. The quality of the precipitate met the requirements for the industrial reuse of CaCO3. In summary, adsorption and carbonation combined were able to remove pollutants from wastewater while recovering useful resources.

Fabrication of coconut shell activated carbon filter system for removal of colour and pollutants in textile dye effluent

The present study evaluates the Decolorization and pollutant removal efficiency of chemically impregnated coconut shell-activated carbon using textile dye effluent in the filtration system. The coconut shell zinc chloride activated carbon (CSZAC) was used as a filtering media in wastewater treatment due to its wider pore space with better surface area (590.80 m2 g−1) and higher adsorption capacity. The SEM micrograph revealed that the activated carbon had networks of parallel running pores with internal microstructure and more active sites. The designed activated carbon filter system has dimensions of 90 x 60 x 30 cm; the sections included are the holding tank (50 liters capacity), filtration tank and storage tank with the optimized flow rate of 5 x 10−4 m3 min−1. The Color, pH, EC, TDS, TSS, BOD and COD of textile dyeing wastewater were significantly reduced, after the treatment through the CSZAC filtration system. The initial color concentration of textile dye effluent was 7021 HU and after treatment, the color was fully reduced and became colorless. CSZAC treatment reduced the BOD from 600 mg L−1 to 89.7 mg L−1 (80.6 per cent) and COD from 2500 mg L−1 to 205 mg L−1 (90.5 per cent). Therefore, CSZAC can be used as an effective adsorbent material to remove different dye compounds and pollutants from textile wastewater.

Removal of sulfamethoxazole using Fe-Mn biochar filtration columns: Influence of co-existing polystyrene microplastics

Emerging contaminants, particularly antibiotics and microplastics (MPs), present significant challenges in wastewater treatment and pose large ecological risks. This study investigates the removal efficiency of sulfamethoxazole (SMX) using Fe-Mn modified biochar (BFM) in fixed bed filtration columns, emphasizing the effect of the presence of polystyrene microplastics (PS-MPs) on SMX behavior in both water (pH ≈ 5.6) and selected wastewater (pH ≈ 8) systems. Batch sorption results show that 10 mg/L SMX in 50 mL water can be completely removed by 100 mg BFM sorbent. The Bed Depth Service Time model indicated the BFM column is feasible for SMX removal in scaled-up continuous wastewater flow operations, while the Yan model best elucidates SMX filtration behavior and suggests the dominant adsorption mechanisms include external mass transfer and intraparticle diffusion. The present of both 20 mg/L and 100 mg/L PS-MPs (pH ≈ 5.6) significantly reduced SMX retention due to competitive sorption. However, at pH 3.2, competitive sorption became negligible due to electrostatic interactions driving the PS-MPs sorption, while neutral charged SMX bound through hydrogen-bonds or π-π EDA interactions. Elevated pH shifted both PS-MPs and SMX sorption to non-electrostatic thus intensifying sorption competition, highlighting the influence of pH on their interaction dynamics. In wastewater, SMX filtration was slightly inhibited by 100 mg/L PS-MPs in BFM columns, whereas PS-MPs removal remained unaffected due to the high ionic strength and alkaline pH. These findings highlight the impact of MPs on pollution removal efficiency in filtration system, essential for enhancing biochar-based wastewater treatment strategies.

A Novel Approach to Waste Recycling and Dye Removal: Lithium-Functionalized Nanoparticle Zeolites.

A zeolitic sample, named MT-ZLSH, was synthesized using mining tailings (MT) as the precursor material, resulting in a structure comprising: Linde type A (LTA) and sodalite-hydroxysodalite (ZLSH). This naming convention reflects the material's origin and its structural characteristics. The material was further modified by incorporating lithium, producing MT-ZLSH-Li+. Physicochemical characterizations were performed, and the material was evaluated for its potential to remove methylene blue (MB) from synthetic wastewater through adsorption and photocatalysis. Efficient adsorption was observed under typical wastewater pH conditions, with a maximum adsorption capacity of 23.4 mg·g-1, which fit well with the Langmuir isotherm model. The key mechanisms governing MB adsorption were identified as ion exchange, electrostatic attraction, and hydrogen bonding. The adsorption process was exothermic, with kinetic data fitting both the pseudo-second order and intraparticle diffusion models, achieving 82% removal and a maximum adsorption capacity of 40 mg·g-1 over 12 h. MB adsorption followed a two-step process, initially involving film diffusion, followed by intraparticle diffusion. Additionally, photocatalytic degradation of MB achieved 77% degradation within 180 min. However, a decrease in reusability was observed during a second cycle of MB adsorption and photodegradation, highlighting the need for further optimization to enhance the material's long-term performance.

Artificial intelligence-driven control for enhancing carbon dioxide-based wastewater pH regulation in tubular reactor

Alkaline wastewater treatment using carbon dioxide can reduce chemical costs and provide a safer alternative to traditional methods. However, complex gas-liquid reactions and narrow operating pH ranges present challenges. This research develops an artificial intelligence-driven control system for treating alkaline wastewater using carbon dioxide in a bench-scale tubular reactor. The proposed control system employs an inverse neural network to regulate the carbon dioxide gas based on the desired setpoint, along with a Smith predictor and a linear controller to compensate for natural delays, model mismatches, and pH disturbances. The inverse neural controller was trained using experimental data from a bench-scale reactor pH treatment of synthetic alkaline wastewater and verified on real influent from an electroplating wastewater treatment plant. The results show that the proposed method efficiently enforces the desired reactor outlet pH setpoint with up to 51.36% faster settling time than a proportional-integral controller while improving pH-adjusting efficiency by 72.24%.

A Luminescent MOF-Based Sensor for Monitoring of an Anticancer Drug and a Pyrethroid Fungicide Biomarker in Wastewater and Biological Fluids.

The extensive use of insecticides, such as pyrethroids, and pharmaceutical drugs, such as doxorubicin (DOX) has significantly increased to meet the growing demand for food production and disease treatment. Among them, 3-phenoxybenzoic acid (3-PBA), a metabolite of pyrethroid insecticides, poses various health and environmental risks. Similarly, DOX is a well-known anticancer drug and has been continuously used for many years. The high demand and unregulated disposal of these substances raise concerns for both humans and the environment. To address this issue, there is a pressing need to monitor the presence of these analytes in wastewater to protect our ecosystems. This challenge has inspired us to develop an MOF-based fluorometric dual sensor capable of rapid and selective detection of these analytes in aqueous solutions. This work represents the first MOF-based dual probe for detecting these targeted analytes. There was a 98% fluorescence quenching upon the introduction of DOX whereas about a 11-fold increment of the probe's fluorescence intensity took place in the presence of 3-PBA. The sensitivity of the probe is notably high as limits of detection (LOD) are 8.7 nM for DOX and 1.2 nM for 3-PBA. Our designed probe has the highest KSV value for DOX which is 3.37 × 106 M-1. The MOF demonstrated remarkable rapid response time of just 5 and 10 s for DOX and 3-PBA, respectively. The MOF exhibited outstanding selectivity in detecting DOX and 3-PBA, even when other interfering substances were present. We tested the probe's sensing abilities in various environments, such as serum, urine, wastewater, and different pH levels. These findings underscore the sensor's practicality and usefulness in real-world applications. The underlying mechanisms driving the sensing processes were thoroughly investigated by using various modern analytical methods.

Towards Sustainable Mining: Evaluating Pyrometallurgy as a Green Alternative in Gold Ore Processing

Environmental pollution by mercury in small-scale gold mining in Kulon Progo has occurred. Amalgamation has been carried out since 1997. It caused many impacts to the environment and human health. It contaminated soil and water in Kalirejo, Kulon Progo. Referring to Minamata Convention through Law Number 11 of 2017, Indonesia through Technology Assessment and Application Agency was collaborating with United Nations Development Program for the development of a pilot plant pyrometallurgy in Kulon Progo. This study aimed to evaluate the effectiveness of pyrometallurgy methods. The research method was assessment research. This research used purposive sampling to collect data and the weighting method to process questionnaire data. Based on the research, pyrometallurgy was still not practical due to its high operational costs. On the other hand, it was environmentally friendly. The heavy metals and pH of wastewater from the scrubber of the arc furnace and roasting met the quality standards. It was possible to switch to pyrometallurgy with a society approval level of 64%..

Biochar accelerates methane production efficiency from Baijiu wastewater: Some viewpoints considering direct interspecies electron transfer

The low pH of Maotai-flavor Baijiu wastewater (MFBW) adversely affects its anaerobic digestion (AD) performance, resulting in low AD efficiency. Here, coconut shell was used to produce biochar. The characteristics of biochar were regulated through acid, alkali, and magnetic modification, respectively. Biochar and modified biochars were applied to assist the AD of MFBW. The results showed that biochar could significantly increase methane yield by 220.8 %–241.7 % with the corresponding soluble chemical oxygen demand (sCOD) degradation increasing by 52.3 %–57.5 % (p < 0.05). Joint modification could significantly enhance the electron donating capacity from 0.0042 to 0.0095 mmol e−1/g (p < 0.05). The combined modification with magnetic alkali had the best stimulating effect on the AD process, which might be related to the conductive particles (Fe3O4) formed during magnetization processes. The modified biochar featured a high degree of surface roughness, a relatively large aperture, and strong electron donating ability, all of which were beneficial to the colonization and microbial growth. Supplementation with biochar resulted in the enrichment of Proteobacteria, Firmicutes, and Actinobacteria, especially for Syntrophomonas (rising from 0.013 % to 6.74 %–10.93 % of relative abundance). These microorganisms are related to the hydrolysis, acidification, and extracellular electron transfer. The enrichment of electroactive microorganism is a prerequisite for improving the direct interspecies electron transfer pathway. This study provides theoretical support for efficient MFBW treatment.

Improving contaminant removal and inhibiting CH4 and H2S emissions from septic tanks: Nitrified human urine as a source of electron acceptor

Septic tanks are widely adopted in decentralized household wastewater treatment systems serving billions of people globally. Due to the lack of effective electron acceptors, insufficient nutrient removal and the emission of harmful gases, e. g. H2S, CH4, etc., are the common drawbacks. In the present work, we attempted to supplement nitrite into septic tanks as an electron acceptor, via nitrifying human urine source-separated from blackwater, to overcome these drawbacks. Partial or complete nitritation of source-separated urine was achieved in a sequencing batch reactor. The addition of nitrified urine into septic tanks improved organic and nitrogen removals in blackwater up to 90 % and 70 %, respectively. The emission of harmful gases from the septic tanks was stably diminished, with more than 75 % of CH4, CO2 and H2S reductions. Nitrite addition significantly reduced the abundance of hydrogenotrophic methanogens in septic tanks. Though the activity of sulfate-reducing bacteria recovered after the initial inhibition upon nitrite addition, the bio-generated H2S was retained in water since the increased wastewater pH after nitrite addition promoted the disassociation of H2S in aqueous solution.