Wastewater Treatment Technologies Research Articles

Test the Effectiveness of Eco-Enzyme Bioremediation as a Reducing Agent for Natural Stone Waste on Rice Plant Productivity and Water Quality in Dukupuntang District

Water is a natural resource that is needed for all living things. Likewise with the river used for irrigation of agricultural land. The Cigayem River is located in Dukupuntang District, Cirebon Regency. Above the river there are many natural stone cottage industries. The processing of natural stone into decorative stone requires a lot of water for its processing, so that a lot of river water in this area is polluted from this home industry activity. The waste is in the form of powder cut from natural stone with water which is directly channeled into irrigation canals without being processed first. The effect is siltation of irrigation canals and decreased water quality. This decrease in water quality has an impact on rice productivity in heavily affected areas. Pollution that occurs in irrigation canals in the study area can be identified by physical changes such as color and other impacts such as decreased productivity of rice yields in the study area since the establishment of the natural stone industry. The decline in rice productivity will threaten the sustainability of rice farming in central areas. Wastewater treatment technology has been developed a lot, but not all home industries can carry out waste treatment at a high cost. Eco enzyme can be a solution to waste pollution that pollutes rivers at a relatively low cost, easy to obtain and sustainable because all materials do not contain harmful chemicals and residues.

Simultaneous nitrate and phosphorus removal in novel steel slag biofilters: Optimization and mechanism study

The simultaneous nitrate (NO3−-N) and phosphorus (P) removal systems are considered to be an effective wastewater treatment technology. However, so far, there are few studies on system optimization to improve NO3−-N and P removal. In this study, nine simultaneous NO3−-N and P removal biofilters (SNPBs) were constructed to treat simulated wastewater. In order to optimize the NO3−-N and P removal, different material loading positions were set: (1) red soil, steel slag, and rice straw (RSR), (2) steel slag, red soil, and rice straw (SRR), and (3) red soil, rice straw, and steel slag (RRS). Results showed that the above three treatments had mean removal efficiencies of 58%–91% for NO3−-N and 55%–81% for TP, with the best N and P removal occurring in the SRR. The TN mass balance indicated that microbial removal was responsible for 78.2% of the influent TN in the SRR biofilter. The key microorganisms were Enterobacter, Klebsiella, Pseudomonas, Diaphorobacter, and unclassified_f_Enterobacteriaceae, which accounted for 61.9% of the total microorganisms. The main P-removal mechanism was the formation of Al–P, Fe–P, and Ca–P in red soil or steel slag layer. In addition, the decrease of SRR effluent pH from 11.86 in 1–7 days to 7.75 in 8–50 days indicated that red soil and rice straw had a synergistic effect on water pH reduction. These results suggest that a reasonable combination of steel slag with red soil and rice straw not only simultaneously removes NO3−-N and P but also additionally solves the problem of high pH caused by steel slag.

Electrochemical treatment of municipal reverse osmosis concentrates by a TiO2-BNTs/SnO2-Sb reactive electrochemical membrane

With the wide application of reverse osmosis technology in municipal wastewater treatment, the abundance of generated reverse osmosis concentrates (ROC) has become a significant challenge for water ecosystems. In this work, a fabricated TiO2-BNTs/SnO2-Sb reactive electrochemical membrane (REM) was used to dispose of municipal ROC wastewater. The effects of the TiO2 nanotube array (TiO2-BNTs) interlayer, current density, initial pH and flow rate on the COD removal of ROC were investigated. In addition, the 3D-EEM fluorescence spectra showed that humic acid-like substances and soluble microbial byproduct-like substances could be removed effectively. GC-MS analysis indicated that most organics, including aldehydes, phenols, ethers, nitriles, ketones, silanes and alcohols, were eliminated after treatment. The REM also exhibited prominent membrane anti-fouling performance in high-salinity wastewater. After 20 cycles, the transmembrane pressure (TMP) was only slightly changed (within 3 kPa) compared to that of the first cycle. Two key parameters, i.e., service lifetime and energy consumption, were investigated in ROC treatment. The service lifetime reached 31350 h (3.5 years, 20 mA cm−2) in 0.5 M NaCl solution and 40390 h (20 mA cm−2, 4.6 years) in actual wastewater, which is highly competitive with previously reported electrodes. Energy consumption reached 10.5 kWh·kg COD−1 in actual ROC wastewater, which is more acceptable compared with current reported electrochemical technologies and exhibits great application prospects for TiO2-BNTs/SnO2-Sb REMs.

A Subsurface Horizontal Constructed Wetland Design Approach for Wastewater Treatment: Application in Ar Riyadh, Saudi Arabia

In this study, a decentralized new sewage water treatment system is suggested and designed in Ar Riyadh, Saudi Arabia, to safeguard the environment and reuse treated water for irrigation purposes. The system consists of a primary treatment (septic tank), a subsurface horizontal flow constructed wetland (HSSF-CW), and a storage ground tank. The research methodology employed in this study is (i) to define the wastewater characteristics, where air temperature in winter is 18.6 °C, the wastewater flow per person (q) is 150 L/d, demonstrating an inlet design discharge of 300 m3/d, the influent pollutant concentrations for biological oxygen demand (BOD), total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and fecal coliforms (FC) are 350, 1000, 700, 50, 12 mg/L, and 106 CFU/100 mL, respectively; (ii) to design the septic tank based on a retention time of two days and a surfacing load rate of 1.5 m/d; (iii) the P-k-C* model was used to determine the HSSF-CW surface area based on reed beds of Phragmites australis (common reed) and papyrus plants, where the removal rate was constant at 20 °C for BOD, TP, and FC in the effluent concentrations not exceeding 20 mg/L, 3.0 mg/L, and 2000 CFU/100 mL in order to satisfy Saudi Arabia’s wastewater reuse requirements; and (iv) to design the clean water tank for a hydraulic retention time of 10 h. The results demonstrate that the removing pollutants design area is 1872 m2 divided into nine cells, each of width 8 m and length 26 m, with a hydraulic loading rate (LR) of 0.16 m/d and a hydraulic resident time (RT) of 1.1 d. The effluent pollutant concentrations for the BOD, FC, TN, and TP were 245 mg/L, 103 CFU/100 mL, 35, and 8.5 mg/L, respectively. The wastewater treatment system total removal efficiencies for BOD, TN, TP, and FC were estimated to be 91.8, 70, 57, and 98.5%, respectively. Design curves were developed to ease the design steps. The HSSF-CW is a green wastewater treatment technology that offers greatly decreased investment costs, and service particularly for small-scale applications up to 6000 persons.

Treatment of aquaculture wastewater by C-MFCs

Chlorella microbial fuel cells (C-MFCs) may be an alternative technology for wastewater treatment. Using microalgae and activated sludge as raw materials, the anode of the MFC was connected in series with a chlorella reactor to establish C-MFCs, so that the simulated aquaculture wastewater was first anaerobically treated in the anode chamber and then aerobically treated in the chlorella reactor. The study found that at a 3:1 N:P ratio and 1000 Ω external resistance, NH3N, COD, and TP removal rates were 69.93 ± 1.84 %, 80.30 ± 3.4 %, and 54.44 ± 4.5 %, respectively, with a maximum chlorophyll content of 0.1049 mg∙m−3. The maximum voltage and maximum power density of 32.94423 mV and 102.37 mW∙m−2. The microbial community structure of the anode chamber was analyzed and the results were as follows: At N:P = 3:1, the dominant bacteria at the genus level in the anode chamber were Klebsiella (47.23 %) and Glucuronobacterium (28.87 %). It can be concluded that N:P affects the power generation capacity of C-MFCs and the removal of NH3N, COD, and TP. The power generation capacity and removal of NH3N, COD, and TP by C-MFCs were best when N:P = 3:1. The regulation of nitrogen and phosphorus in aquaculture wastewater can effectively enhance the performance of C-MFCs.

Enhanced performance of microbial fuel cells using electrochemically treated carbon felt anode

The microbial fuel cell (MFC) technology is emerging as an effective technology for wastewater treatment to remove and detect many pollutants and simultaneously generate power. The anode is an essential component for bacterial attachment and extracellular electron transfer (EET). Thus, anode performance is critical for improving an MFC system's overall performance. Materials that are electronically conductive and provide favorable conditions for creating biofilm are good candidates for the anode. Carbon paper and carbon felt are the most used anode materials. However, the characteristics of these materials can be modified to increase their performance. This paper presents a modification of the conventional carbon anode by electrolyzing the carbon felt in a phosphate buffer and an experimental evaluation of the impact of the treatment. The tests were performed using an air cathode MFC, electrogenic bacteria Shewanella Baltica 20 fed on lactose-rich L-B. The treatment with phosphate buffer generates functional groups on the surface of the carbon felt, which establishes robust biofilm on the anode and offers lower charge-transfer resistance compared to the untreated carbon felt. This facilitates electron transfer from exoelectrogens to the anode, increasing the current density and power density output. Three times higher power density was observed in the cell with a modified anode than in an untreated carbon-felt anode.

Synthesis of a reusable magnetic photocatalyst based on BiOCl / MnxZn1-xFe2O4 composites and its application on RhB degradation

Water pollution is becoming an increasingly serious issue, which threatens human survival. However, existing technology for addressing this issue has not developed adequately, and the recovery of polluted water remains difficult. Therefore, it is critical to develop innovative wastewater treatment technology, which is highly effective, uses little energy, and produces no secondary pollution. In this study, a Z-type heterojunction BiOCl/MnxZn1-xFe2O4 magnetic composite photocatalyst was created by the hydrothermal method. Using RhB as the target dye, the photocatalytic performances of the composite samples were assessed. The structure of composite samples was studied by SEM, X-ray diffraction, and UV–vis diffuse reflectance spectroscopy.The findings demonstrate that the heterojunction created by the addition of MnxZn1-xFe2O4 and BiOCl lowers the rate at which photogenerated electrons and holes recombine. Meanwhile, the prepared BiOCl/MnxZn1-xFe2O4 magnetic composite photocatalyst exhibited a notable catalytic degradation effect on RhB. Among them, the degradation rate of BiMn-5 was as high as 94.6%, showing better photocatalytic performance than other composite samples with different mass ratios. In addition, the product can be recycled. After five repeated tests, the average degradation rate remained as high as 88.7%. Therefore, the BiOCl/MnxZn1-xFe2O4 magnetic composite photocatalyst developed herein can be a new technology for efficient and environmentally friendly sewage treatment in line with contemporary needs.

Applications of electro-catalysis municipal wastewater treatment

In the context of developing a more livable environment, people are paying more attention to the pollution problem. As the consumption of water resources increases, water pollution is one of the most serious problems people need to pay attention to the most. However, traditional methods cannot meet the requirements of treating wastewater while recovering resources. In this review, the application of electrocatalytic technology in municipal wastewater treatment is discussed. Specifically, the comparison between electrocatalysis and traditional methods is shown in this review. Various literatures on different types of materials of electrodes are included. Besides, two different types of electrodes and mechanisms of electrocatalysis and their application in multiple types of wastewater are also summarized. This review aims to arouse peoples attention to the wastewater problem and explore the further application of electrocatalytic technology in the future in order to rationally design new electrocatalytic systems for the recovery of energy and resources.

Biological Treatment of Industrial Wastewater

The objective of this study is to explore in depth the biological treatment technologies for industrial wastewater and to analyze their application and development with the aim of improving the efficiency of industrial wastewater treatment, reducing costs, and minimizing the adverse effects on the environment. Specifically, it includes: systematically summarizing and comparing the current common biological treatment technologies for industrial wastewater, analyzing their advantages and disadvantages, scope of application, and effectiveness, in order to improve the understanding and control of the biological treatment process. Biofilm treatment technologies include fluidized bed biofilm reactor (FBBR), membrane biofilm reactor (MBfR), moving bed biofilm reactor (MBBR), and rotating biological contactor (RBC). Further research and innovation are needed to improve treatment efficiency, reduce energy consumption and anaerobic treatment, control membrane pollution and degrade difficult-to-biodegrade substances.

Synthesis and immobilization of HC/BiVO4 catalyst particles with PTFE for photocatalytic tetracycline degradation: Preparation, performance and mechanism

The hydrothermal carbon/bismuth vanadate (HC/BiVO4) composite catalyst particles were prepared by one-step hydrothermal process. For effective and convenient photocatalytic organics degradation, the sandwich-like immobilization of HC/BiVO4 particles was performed utilizing polytetrafluoroethylene (PTFE) as an adhesive agent, NaCl as a pore-creating agent and PTFE/graphite composite as the interlayer. The obtained results indicated that HC/BiVO4 exhibited the higher performance than the pure BiVO4 towards photocatalytic tetracycline degradation owing to its enhanced separation of electron-hole (e−-h+) pairs as well as relatively higher electron transfer ability. Four active species including superoxide anion radical (O2−), h+, hydroxyl radical (OH) and singlet oxygen (1O2) could be identified from the developed photocatalytic system, whereas O2− played the predominant role in tetracycline degradation. It was found that the immobilized photocatalyst owned a certain photocatalytic degradation activity, fine renew-ability and high mechanical strength. The pore-creating function of NaCl particles enhanced the immobilized photocatalyst's photocatalytic performance evidently. The photocatalytic treatment of tetracycline solution by the immobilized catalyst presented the removal efficiency of over 90 % in 120 min. In addition, after the degradation, the biodegradability of the solution was enhanced evidently due to the generation of readily biodegradable organic intermediates. This study mainly presents a new method to prepare the immobilized HC/BiVO4 photocatalyst promoting the application of photocatalytic technology in organic wastewater treatment.

Treatment and Prospects of Industrial Wastewater with Biochar

As the process of industrialization accelerates, finding effective methods for industrial wastewater treatment has become an important task in the field of environmental protection. However, despite the preparation methods and properties of biochar have been studied, its large-scale application in industrial wastewater treatment has not yet been fully understood and clarified. This paper first analyzes the industrial wastewater to be treated, and combines the mechanism of biochar in treating industrial wastewater, elaborates the cases of biochar applied in real life and the corresponding difficulties. The research results show that biochar is a material with good application potential for industrial wastewater treatment. Its high specific surface area and rich surface functional groups give it good adsorption capacity for various pollutants in industrial wastewater. In addition, the adsorption performance of biochar can be optimized by adjusting its preparation and application conditions. Future research should further explore the long-term stability of biochar in the treatment of industrial wastewater, as well as its application effect in the actual industrial environment. In addition, the development of efficient, economical, and controllable technologies for the preparation and application of biochar, and promoting its large-scale application in industrial wastewater treatment, are also important directions for future research. The research in this paper is of great significance for understanding and utilizing biochar for the treatment of industrial wastewater. The results not only help to improve the efficiency and effectiveness of industrial wastewater treatment, but also provide new ideas and methods for the high-value utilization of waste biomass. Therefore, this research has important theoretical and practical value for promoting the development of industrial wastewater treatment technology and achieving sustainable utilization of environmental protection and resources.

Partitioning and inactivation of enveloped and nonenveloped viruses in activated sludge, anaerobic and microalgae-based wastewater treatment systems

Anaerobic and microalgae-based technologies for municipal wastewater treatment have emerged as sustainable alternatives to activated sludge systems. However, viruses are a major sanitary concern for reuse applications of liquid and solid byproducts from these technologies. To assess their capacity to reduce viruses during secondary wastewater treatment, enveloped Phi6 and nonenveloped MS2 bacteriophages, typically used as surrogates of several types of wastewater viruses, were spiked into batch bioreactors treating synthetic municipal wastewater (SMWW). The decay of Phi6 and MS2 in anaerobic and microalgae-based reactors was compared with the decay in activated sludge batch reactors for 96 h (Phi6) and 144 h (MS2). In each reactor, bacteriophages in the soluble and solids fractions were titered, allowing the assessment of virus partitioning to biomass over time. Moreover, the influence of abiotic conditions such as agitation, oxygen absence and light excess in activated sludge, anaerobic and microalgae reactors, respectively, was assessed using dedicated SMWW control reactors. All technologies showed Phi6 and MS2 reductions. Phi6 was reduced in at least 4.7 to 6.5 log10 units, with 0 h concentrations ranging from 5.0 to 6.5 log10 PFU mL−1. Similarly, reductions achieved for MS2 were of at least 3.9 to 7.2 log10 units, from starting concentrations of 8.0 to 8.6 log10 PFU mL−1. Log-logistic models adjusted to bacteriophages’ decay indicated T90 values in activated sludge and microalgae reactors of 2.2 and 7.9 h for Phi6 and of 1.0 and 11.5 h for MS2, respectively, all within typical hydraulic retention times (HRT) of full-scale operation. In the case of the microalgae technology, T99 values for Phi6 and MS2 of 12.7 h and 13.6 h were also lower than typical operating HRTs (2–10 d), while activated sludge and anaerobic treatment achieved less than 99 % of Phi6 and 50 % of MS2 inactivation within 12 h of typical HRT, respectively. Thus, the microalgae-based treatment exhibited a higher potential to reduce the disinfection requirements of treated wastewater.

The environmental risk assessment of constructed wetlands filled with iron and manganese ores in typical antibiotic treatment

Constructed wetlands (CWs) is considered as an efficient and environmentally friendly technology for advanced wastewater treatment to eliminate organic pollutants such as sulfamethoxazole (SMX) and trimethoprim (TMP). Iron (Fe) and manganese (Mn) ores have attracted more and more attention as CWs substrates in treating SMX and TMP, but the potentially negative environmental effects of wetland effluents, ore contaminants leached from the substrates and the risk of transmission of antibiotic resistance genes (ARGs) are still not clear. Three CW groups with different substrates (river sand (C-CW), Fe ore (Fe-CW), and Mn ore (Mn-CW)) were set up to evaluate the average removal rates and environmental risk in treating wastewater containing SMX and TMP. The results showed that the average removal rates of SMX and TMP by Fe-CW and Mn-CW were significantly higher than that of C-CW by 12.46%, 6.59% and 38.93%,15.39% respectively (p < 0.05), suggesting that both Fe and Mn ores facilitated the removal of antibiotics. However, the least abundance of ARGs was found in the layer of Fe ore at the middle layer (ML) in Fe-CW among all CWs, which suggested that Fe ore could reduce the risk of ARGs transmission. Although the environmental risk of Fe-CW and Mn-CW effluent was low, Fe-CW effluent inhibited the growth of Chlorella in both 48h and 72h experiments, while Mn-CW effluent showed an inhibitory effect in 48h and then promoted the growth in 72h. Meanwhile, these findings offer valuable insights for wetland health assessment and substrate selection for CWs.

Enhanced dechlorination of 2,4-dichlorophenol using nanorod palygorskite-loaded Fe/Ni nanoparticles: Performance evaluation, influencing factors and action mechanism of Fe and Ni

The basic structural unit of palygorskite (P) consists of rod-shaped crystals with a diameter ranging from 20 to 70 nm. However, due to strong hydrogen bonding and electrostatic forces, most palygorskite rod crystals tend to aggregate, limiting its nanomaterial properties in practical application. To address this limitation, the study focused on dissociating palygorskite aggregates and incorporating them into nanorod palygorskite-loaded Fe/Ni bimetallic nanoparticles (nP-nFe/Ni) synthesis. This approach facilitated the dissociation of palygorskite aggregates and enabled the dispersion of Fe/Ni nanoparticles by palygorskite nanorods. The results revealed that the BET specific surface area of nP-nFe/Ni was significantly higher at 86.17 m2/g compared to 33.62 m2/g for nFe/Ni. Consequently, the dechlorination efficiency of nP-nFe/Ni for 2,4-dichlorophenol (2,4-DCP) at 120 min was 22.4% higher than that of nFe/Ni, despite nP-nFe/Ni containing only 35.1% of the Fe content found in nFe/Ni at the same dosage. Moreover, it was observed that acidic conditions favor maximum dichlorination, while higher temperatures enhance the dechlorination rate. The action mechanism of Fe was identified as the generation of H2, which is catalyzed by Ni to form active hydrogen (H*) that attack the C-Cl bonds of 2,4-DCP for hydrodechlorination. Ni played a vital role in catalyzing H2 conversion to H* , accelerating H2 production by Fe, and inhibiting Fe passivation. These findings are crucial for the application of nano iron technology and nano-scale palygorskite in water and wastewater treatment.

Phosphorus removal from ore waste in aqueous solution with different mass of ore waste adsorbent from the Johor mine site

Abstract Mine waste management is becoming a growing global environmental concern for mining industries all over the world. Due to the abundance of ore waste from mining industries, this study aimed to observe the possibility of using ore waste to remove phosphorus from a solution. Although phosphorus is one of the essential elements for plant life, excessive phosphorus in water becomes one of the environmental issues, e.g., eutrophication. This study analysed the prediction contour of removal efficiency with the mass of adsorbent needed under different initial concentrations of solution. The batch experiment used an aqueous solution of 5 mg/L using potassium dihydrogen phosphate (KH2PO4) at different masses of adsorbent (2, 4, 6, 8, 10 g). The highest removal efficiency for phosphorus using 10 g of adsorbent is 54.3%. The data verified that the pseudo-second-order model (0.9976) fitted well. The adsorption between ore waste adsorbent and phosphorus was chemical sorption, whereas the analysis of isotherm models fitted the Freundlich model, with the occurrence of multilayer adsorption on the adsorption surface. The ability of ore waste to remove phosphorus was successful. This approach is one of the alternatives to enhance tertiary wastewater treatment technologies.

Monitoring of domestic wastewater treatment via infiltration percolation using impedance spectroscopy

In this study, we treated domestic wastewater originating from the city of Oulad Frej using a novel treatment technology called percolation infiltration. The filtration medium consisted of a mixture of fly ash and sea sand sourced from the coast of Essaouiria. The filtration process yielded remarkable results, achieving an impressive reduction of 80% in COD, 70% in BOD5, 86% in suspended matter (SM), and 81–99% in heavy metals. Moreover, significant improvements were observed in terms of discoloration and pH reduction. To assess the efficacy of the domestic wastewater treatment technology, we introduced a new key indicator, complex conductivity σ * (ω), and monitored its changes before and after treatment. The impedance spectra analysis showed a strong correlation with the parameters obtained through conventional methods.

ASSESSMENT OF SUSTAINABLE WASTEWATER TREATMENT TECHNOLOGIES USING INTERVAL-VALUED INTUITIONISTIC FUZZY DISTANCE MEASURE-BASED MAIRCA METHOD

Effective wastewater treatment has significant effects on saving water and preventing unnecessary water scarcity. An appropriate wastewater treatment technology (WWTT) brings economic benefits through reuse in different sectors and benefits the society and environment. This study aims to develop a decision-making framework for evaluating the sustainable WWTTs under interval-valued intuitionistic fuzzy set (IVIFS) environment. The proposed MCDM framework is divided into two stages. First, a new Hellinger distance measure is developed to determine the degree of difference between IVIFSs and also discussed its desirable characteristics. Second, an interval-valued intuitionistic fuzzy extension of multi-attribute ideal-real comparative analysis (MAIRCA) model is developed using the proposed Hellinger distance measure-based weighting tool. Further, the proposed model is implemented on an empirical study of sustainable WWTTs evaluation problem. Sensitivity and comparative studies are made. The results indicate that odor impacts, sludge production, maintenance and operation are the most effective sustainable factors and Microbial fuel cell (MFC) technology is the best WWTT followed by natural treatment methods.

Distribution, fate and removal efficiency of anthelmintic drugs in wastewater treatment plants

The distribution and fate of 19 anthelmintic drugs (ADs) were investigated in two wastewater treatment plants (WWTPs) using different wastewater treatment technologies, including anaerobic-anoxic-aerobic (A2/O) biological process and cyclic activated sludge system (CASS) process. All the 19 ADs were found in the two WWTPs, with concentrations ranging from N.D. to 324.6 ng/L in the influent and from N.D. to 1579.2 ng/L in the effluent. Benzimidazoles were the primary pollutants in the wastewater and suspended particulate matter, accounting for more than half of the total concentration. The concentrations of macrocyclic lactones in the sludge were significantly higher than that of other two media. The ADs removal efficiency of A2/O ranged from −330 % (albendazole sulfoxide) to 100 % (fenbendazole, mebendazole and pyrantel). While the ADs removal efficiency of CASS process ranged from −425 % (albendazole sulfoxide) to 100 % (abamectin, moxidectin and ivermectin). There was no significant difference in the average removal efficiency of the ADs between the two processes (64 % and 63 %, except albendazole sulfoxide). The removal efficiencies of the ADs in the biodegradation stage were better than them in the sedimentation stage. The load per capita of the 19 ADs in two WWTPs ranged from 0 (moxidectin) to 36 μg.d−1.p−1 (albendazole), and the emission in the effluent ranged from 0 (moxidectin) to 163 μg.d−1.p−1 (albendazole sulfoxide). This study provided the first comprehensive data on the occurrence and fate of the 19 ADs and evaluated the removal efficiencies of the 19 ADs in two WWTPs using A2O process and CASS process in the city.

Datacentric Similarity Matching of Emergent Stigmergic Clustering to Fractional Factorial Vectoring: A Case for Leaner-and-Greener Wastewater Recycling

Water scarcity is a challenging global risk. Urban wastewater treatment technologies, which utilize processes based on single-stage ultrafiltration (UF) or nanofiltration (NF), have the potential to offer lean-and-green cost-effective solutions. Robustifying the effectiveness of water treatment is a complex multidimensional characteristic problem. In this study, a non-linear Taguchi-type orthogonal-array (OA) sampler is enriched with an emergent stigmergic clustering procedure to conduct the screening/optimization of multiple UF/NF aquametric performance metrics. The stochastic solver employs the Databionic swarm intelligence routine to classify the resulting multi-response dataset. Next, a cluster separation measure, the Davies–Bouldin index, is used to evaluate input and output relationships. The self-organized bionic-classifier data-partition appropriateness is matched for signatures between the emergent stigmergic clustering memberships and the OA factorial vector sequences. To illustrate the proposed methodology, recently-published multi-response multifactorial L9(34) OA-planned experiments from two interesting UF-/NF-membrane processes are examined. In the study, seven UF-membrane process characteristics and six NF-membrane process characteristics are tested (1) in relationship to four controlling factors and (2) to synchronously evaluate individual factorial curvatures. The results are compared with other ordinary clustering methods and their performances are discussed. The unsupervised robust bionic prediction reveals that the permeate flux influences both the UF-/NF-membrane process performances. For the UF process and a three-cluster model, the Davies–Bouldin index was minimized at values of 1.89 and 1.27 for the centroid and medoid centrotypes, respectively. For the NF process and a two-cluster model, the Davies–Bouldin index was minimized for both centrotypes at values close to 0.4, which was fairly close to the self-validation value. The advantage of this proposed data-centric engineering scheme relies on its emergent and self-organized clustering capability, which retraces its appropriateness to the fractional factorial rigid structure and, hence, it may become useful for screening and optimizing small-data wastewater operating conditions.

Influence of ferric oxides with varying crystallinity on the enrichment of halophilic exoelectrogens: An application for power generation in microbial fuel cells

Pre-enriching electroactive microbes (EAM) capable of respiration using solid terminal electron acceptors (TEA) is a prospective strategy that promotes faster start-up of bioanodes in microbial fuel cells (MFC) for energy-efficient treatment of saline wastewater. Previous studies demonstrated a reduction in the start-up times of bioanodes with ferric oxides as TEA, though the enriched EAM generated a wide range of current densities as opposed to those using graphene oxide (GO) as TEA. Additionally, the influence of ferric oxides with varying crystallinity on the anode-respiring activity of halophilic EAM is understudied. This study elaborates a systematic investigation into the influence of inoculum sources, different crystallinity of ferric oxides and their redox potentials on the selective enrichment of GO-respiring EAM for developing bioanodes with high current-generating capacity at shorter start-up times. A holistic assessment of the bioanodes, including analysis of their electrochemical performance and generated power densities, revealed that enrichment of GO-respiring EAM with amorphous ferrihydrite as TEA fostered the growth of high-performing biofilms at shorter start-up times (48–72 h) compared to crystalline goethite used as TEA (∼96 h). These biofilms produced power densities ranging from 142 ± 10 mW/m2 to 276 ± 76 mW/m2 with corresponding Coulombic efficiencies of 16 ± 6 % to 30 ± 6 %. Finally, the implications of promising halophilic EAM consortia were explored for saline MFC as a prospective energy-neutral wastewater treatment technology.