Discharge Standards Research Articles

Methods for increasing the number of participants in official computer sports competitions in the Sverdlovsk region

Relevance. The main problem of official computer sports in the Russian Federation is the low motivation of gamers to participate in official sports events. Gamers do not seek to become athletes and fulfill all the requirements imposed by accredited federations to participate in official sports competitions. The purpose of the study is to determine the reasons for the decrease in the number of esports athletes participating in official competitions of the Sverdlovsk region. Methods and organization of research. The authors took to analyze the economic indicators of the development of the sport "computer sport" (the identical term esports), prize payments were selected in the Dota2 game for highly qualified athletes, namely Tier 1 and Tier 2 teams of the world ranking. Payments were recorded for a ten-year period from 2011 to October 2022 for each level. The analysis of the socio-economic characteristics of Dota2 tournaments for Tier 1 and Tier 2 teams showed that there are prerequisites for the formation of professional computer sports and its individual characteristics, such as: the number of tournaments; the number of teams in the Tier 1 tournament; the number of teams in the tournament and the average prize pool for Tier 2 teams. The consequence of low motivation are such problems as low awareness of potential competitors. Lack of motivation to participate in official competitions. Lack of motivation to solve technical problems of organizing your workplace, to participate in competitions. Insufficient number of athletes from the region applying for official competitions to meet the discharge standards. Low social responsibility of athletes in the team types of the program, the lack of stable teams. Analysis of the causes of low awareness, insufficient number of athletes to meet the discharge standards, and ways to solve them. Conclusions. The method of personal notification of athletes allows solving the problem of their low awareness of the dates of official sports competitions.

Performance and mechanism of phosphorus adsorption removal from wastewater by a Ce-Zr-Al composite adsorbent.

With the increasingly serious eutrophication of global water bodies and the strict discharge standards of tail water in wastewater treatment plants (WWTPs), there is an urgent technology need for efficient deep phosphorus removal from wastewater. A composite cerium-based adsorbent (Ce-Zr-Al) was synthesized by coprecipitation method for the adsorption of low concentration phosphorus in water. The performance of the Ce-Zr-Al composite adsorbent was explored, and the mechanism was also revealed through the analyses including SEM, BET, XPS, and FT-IR. The results showed that the composite adsorbent had excellent phosphorus removal performance. The phosphorus removal rate reached up to 92.6%, and the phosphorus concentration in effluent was less than 0.074 mg/L. The phosphate adsorption capacity of saturation was 73.51 mg/g. The adsorption process of phosphate was in accordance with pseudo-second-order kinetic model and Langmuir model. In addition, the composite adsorbent had a high zero potential point (pH PZC= 8) and a wide range of pH application. After the repeated desorption for 10 times in NaOH solution, the composite adsorbent still maintained good adsorbability (adsorption rate > 94%). The ligand exchange and electrostatic adsorption played the main role for the phosphorus removal from water using the composite adsorbent.

Durable Nanofiber-Based Membrane with Efficient and Consistent Performance for Oil/Saltwater Separation

There is a large amount of oil-contaminated wastewater caused by oil/gas production and marine oil spills. It is still a major challenge for the development of oil/water separating membranes that have excellent separation efficiency, can withstand saline environments, and have long-term durability. We present a new membrane made of ultralong titanate nanofibers (TNF) (with diameter of 200 nm and length of 60 µm) and carbon nanofibers (CNF) (with a diameter of 150 nm and length of 50 µm) for efficient and consistent oil/saltwater separation. The intertwined structure of titanate and carbon nanofibers is critical to ensuring a high mechanical strength and durability for the new membrane. The carbon nanofiber works as a scaffold in this membrane to maintain mechanical integrity during multiple cycles of reuses, which is an important merit for its practical applications. The ultralong titanate nanofibers work as functional component to provide high hydrophilicity of the membrane. The new membrane has an oil/water separation efficiency of more than 99%, an oil content in treated effluent that is lower than US environmental discharge standards (42 ppm), and a high water flux of 1520 LMH/bar, due to its excellent superhydrophilicity and inter-connected pore structure. The new membrane also exhibits outstanding durability in a variety of salinity environments, as well as good resistance to oil fouling. This new type of membrane has a high potential for industrial application in treating oily wastewater due to its excellent environmental durability, oil-fouling resistance, high separation efficiency, and easy scalability.

Design of Urban Sludge Emission Reduction Optimisation Strategy Based on Fuzzy Neural Network

Abstract Urban sewage sludge treatment is important for sustainable utilisation and virtuous cycle of freshwater resources. However, with the improvement of sewage discharge standards, ensuring stable operation of sewage sludge treatment plants is becoming an urgent problem to be solved in the sewage treatment industry. This paper proposes a FNN control framework based on different working conditions to optimise the whole process of municipal sewage sludge treatment and discharge. The framework first divides the working conditions according to the weather, forming a separate feature and an input vector together with the typical indicators of other sewage treatment plants. Then the FNN is used to complete the control and optimisation of various indicators, achieving the dual objectives of reducing energy consumption and optimising water quality. Finally, the model is tested for the tracking index of sewage flow. The results demonstrate that the FNN control method used has significantly lower MAE than the single method in the two indexes of energy consumption and water quality evaluation. This provides new ideas for the optimisation of urban sewage sludge treatment process in the future. Overall, the paper effectively highlights the importance of urban sewage sludge treatment and presents a well-designed FNN control framework for optimising the treatment process. Additionally, the paper could benefit from further elaboration on the significance of the results obtained, and suggestions for future research in this area.

Research on Rural Wastewater Treatment Technology in Northwest China Based on Anaerobic Biofilm Coupled with Anaerobic Baffle Plate Reactor (ABR) Technology

The northwest of China has a shortage of water resources, and classic sewage treatment techniques have a high cost and produce waste nitrogen and phosphorus. In order to achieve inexpensive discharge standards, an anaerobic biofilm coupled with ABR technology was adopted as a treatment for normal rural wastewater in the arid and semi-arid vicinity of Northwest China to investigate its operational impact on the treatment of northwest China’s rural domestic wastewater. The results illustrated that the best pollutant elimination effect was reached under the conditions of a set temperature of 35 °C, with a set hydraulic retention time of 3 d and the application of a suspended ball filler as a hanging biofilm carrier. Therefore, the aggregated process can boost the purification capacity and offer a reference to solving the difficulty of sewage discharge in non-agricultural irrigation areas.

Minimum conflict consensus models for group decision-making based on social network analysis considering non-cooperative behaviors

Decision makers (DMs) may exhibit non-cooperative behaviors such as deviating from recommendations or making only minor modifications in consensus-based group decision-making (GDM) problems. These non-cooperative behaviors will lead to high intra-group conflicts and low consensus efficiency. This paper designs a budget-constrained consensus framework with minimum group conflict based on social network analysis to address non-cooperative behaviors. First, the conflict degrees among DMs are quantified by opinion discrepancies and asymmetric 2-tuple linguistic trust values. Then, DMs’ weights are derived by considering degree centrality and node strength indices in the constructed conflict network. To obtain a feasible budget constraint for the consensus, the non-linear optimization models considering non-cooperative behaviors are proposed. Furthermore, two kinds of minimum conflict consensus models are established to deal with general and completely non-cooperative DMs, respectively. The existence of the optimal solutions of these consensus models and the convergence of the consensus reaching process are proved. Finally, the proposed consensus models are illustrated by an example of the negotiation of the sewage discharge standards. Compared with the consensus models based on minimum cost or adjustment, the proposed consensus models could achieve higher consensus and lower group conflict.

Advanced treatment of low-pollution and poor biodegradability sewage by combined process

A system was developed for the treatment of low-pollution sewage with poor biodegradability and a low ratio of chemical oxygen demand (CODCr) to nitrate-nitrogen (COD/NO3−-N (C/N)) ratio to achieve high efficiency. This system combines the anaerobic-oxic (AO) process with the biological aerated filter (BAF) and introduces the Fenton advanced oxidation process. A pilot test system was established, and feasibility investigations were conducted using a continuous flow of 500 L/h. The results showed that the optimal conditions for removing nitrate from sewage were achieved with a C/N ratio of 5.5–6 and a hydraulic retention time (HRT) of 4 h. Under these conditions, the average nitrate removal efficiency was 83.36%, and the average concentration of total nitrogen (TN) in the effluent was reduced to 6.68 mg/L. Additionally, the Fenton oxidation treatment was effective in reducing the COD content of sewage, with an average removal efficiency of 82.47% and a decrease in CODCr from 55.24 mg/L to 9.68 mg/L. The combined process successfully met the stringent discharge standards after advanced treatment. Microbial community analysis revealed that the dominant genera in anoxic BAFs were Trichococcus, Comamonadaceae, Lentimicrobium, and Thauera, while the dominant genera in aerobic BAFs were mainly Acinetobacter, Thiothrix, Gemmobacter, and Caldilineaceae. The synergistic effect of various nitrifying and denitrifying bacteria in BAFs effectively removed nitrate from the sewage. Furthermore, GC-MS analysis indicated that the Fenton oxidation significantly reduced the concentration of refractory organic compounds in the sewage, including long-chain organic compounds and acrylic acid maleic acid copolymer (MA/AA). After upgrading and renovating the factory's sewage treatment facilities, the impact of the discharged effluent on the receiving drainage basin will be minimized.

Microbial metabolism regulation on the efficient degradation of aromatic compounds for biochemical treatment process of coal chemical wastewater in pilot scale

At present, the common problems of biochemical treatment systems of coal chemical wastewater were the poor system stability and the difficulty in reaching COD discharge standards. Aromatic compounds were the main contributors to COD value. The effective removal of aromatic compounds was an urgent problem in the biochemical treatment systems of coal chemical wastewater. In this study, the dominant microbial strains that could degrade phenol, quinoline, and phenanthrene were isolated respectively and inoculated into the pilot scale biochemical tank of coal chemical wastewater. The regulation effect and mechanism of microbial metabolism on the efficient degradation of aromatic compounds were studied. The results indicated that the various aromatic compounds were significantly removed under the regulation of microbial metabolism, the removal efficiencies of COD, TOC, phenols, benzenes, N-CHs, and PAHs were increased by about 25%, 20%, 33%, 25%, 42%, and 45%, respectively, and their biotoxicity was also drastically reduced. Moreover, the abundance and diversity of microbial community, and the microbial activity were obviously improved, as well as the various functional strains were selectively enriched, suggesting that the regulation system could resist environmental stresses with high substrate concentration and toxicity, which could lead to more enhanced performance for aromatic compounds removal. In addition, the microbial EPS content was significantly increased, implying the formation of microbial hydrophobic cell surfaces, which could improve the bioavailability of aromatic compounds. Furthermore, the enzymatic activity analysis revealed that the relative abundance and activity of key enzymes were all obviously improved. In conclusion, multiple lines of evidence were provided to clarify the regulation mechanism of microbial metabolism on the efficient degradation of aromatic compounds for biochemical treatment process of coal chemical wastewater in pilot scale. The results laid a good foundation for realizing the harmless treatment of coal chemical wastewater.

The assessment of compatibility of wastewater treated by natural lagoon with discharge and irrigation standards. Case study

In order to protect the environment and the groundwater against pollution, we dealt with one of the problems in the world, regarding the treatment of wastewater and the possibility of reuse with irrigation. We studied the case of the Kef Eddouken natural lagoon treatment plant in Ghardaia (southern Algeria). For this reason we studied the physico-chemical, bacteriological and parsitological parameter of waste and treated water. The results of the analysis show that all the previous parameters comply with the Algerian standard of rejection except electrical conductivity, suspended matter and BOD5. On the other hand, despite the electrical conductivity exceeds the limit, but it corresponds to the SAR value; according to the Algerian and the international standard of irrigation, this quality of water can be used sub-irrigation for vegetable which eaten only cooked.

Study on the Treatment of Refined Sugar Wastewater by Electrodialysis Coupled with Upflow Anaerobic Sludge Blanket and Membrane Bioreactor.

In this paper, refined sugar wastewater (RSW) is treated by electrodialysis (ED) coupled with an upflow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR). The salt in RSW was first removed by ED, and then the remaining organic components in RSW were degraded by a combined UASB and MBR system. In the batch operation of ED, the RSW was desalinated to a certain level (conductivity < 6 mS·cm-1) at different dilute to concentrated stream volume ratios (VD/VC). At the volume ratio of 5:1, the salt migration rate JR and COD migration rate JCOD were 283.9 g·h-1·m-2 and 13.84 g·h-1·m-2, respectively, and the separation factor α (defined as JCOD/JR) reached a minimum value of 0.0487. The ion exchange capacity (IEC) of ion exchange membranes (IEMs) after 5 months of usage showed a slight change from 2.3 mmol·g-1 to 1.8 mmol·g-1. After the ED treatment, the effluent from the tank of the dilute stream was introduced into the combined UASB-MBR system. In the stabilization stage, the average COD of UASB effluent was 2048 mg·L-1, and the effluent COD of MBR was maintained below 44-69 mg·L-1, which met the discharge standard of water contaminants for the sugar industry. The coupled method reported here provides a viable idea and an effective reference for treating RSW and other similar industrial wastewaters with high salinity and organic contents.

Old Landfill Leachate and Municipal Wastewater Co-Treatment by Sequencing Batch Reactor Combined with Coagulation–Flocculation Using Novel Flocculant

The use of novel flocculants in combination with a sequencing batch reactor (SBR) for the treatment of landfill leachate and municipal wastewater has been shown to be an effective method for reducing polluted effluents. Co-treatment of landfill leachate with a mixture of municipal wastewater was performed at 5%, 10%, 15% and 20% in SBR and effluent was treated by coagulation–flocculation. SBR with 6 d hydraulic retention time (HRT) and 30 d solids retention time (SRT) removed 58 to 70% COD, 86 to 93% ammonia, 76 to 83% nitrate and 69 to 95% phosphate. Coagulation–flocculation with different dosages of alum and ferric chloride with polyacrylamide grafted gum ghatti (GGI-g-PAM) as a novel flocculant was used for chemical oxygen demand (COD), turbidity, total suspended solids (TSS) and color removal. Maximum COD removal was at 20% leachate, which was 74% with alum at 2800 mg/L and 77% with ferric chloride at 470 mg/L. Alum and ferric chloride with GGI-g-PAM flocculant removed 96% and 82% of turbidity and 80% and 82% TSS, respectively. At 20% leachate, combined treatment with SBR and coagulation–flocculation resulted in the total removal of 89% COD, 83% ammonia, 82% nitrate 98% turbidity and 93% TSS with alum. The combined treatment with ferric chloride resulted in a removal of 90% COD, 86% ammonia, 83% nitrate, 98% turbidity and 94% TSS. Except for nitrate combined treatment with both the coagulants at 20% landfill leachate to municipal wastewater ratio removed COD, ammonia, phosphate and TSS to a level that met international standards for discharges to inland surface water. As such, the use of new flocculants with SBR can help reduce water pollution from landfill leachate and municipal wastewater. In addition to coagulation–flocculation, other physico–chemical processes can also be studied as post-treatment options for the co-treatment of wastewater mixture.

Identification of microbial communities and functional genes in an anaerobic-anoxic-oxic (A2O) process in responding to the iron-carbon micro-electrolysis (ICME) pre-treatment of electroplating wastewater based on high-throughput sequencing

Industrial wastewater contains high concentrations of refractory organic carbons, resulting in a low biodegradability difficult for the following biological treatments. The iron-carbon micro-electrolysis (ICME) was developed to break down the larger organic molecules and enhance the biodegradability. Previous ICME pretreatment coupling studies focused primarily on pharmaceutical, dye, and medical wastewater. In this study, the ICME was applied to treat the electroplating wastewater with surfactants, followed by an anaerobic-anoxic-oxic (A2O) biological process. When the ratio of the ICME-treated wastewater was low (10 %), the strike on nutrient removal efficiency (chemical oxidation demand, ammonia, total nitrogen, and total phosphate) was almost negligible. With the increase of ICME-treated wastewater up to 50 %, the removal efficiency gradually decreased, but the effluent water quality still met the discharge standard. Meanwhile, a shift of microbial communities in the three zones was also observed after the 50-day incubation. The abundance of Hydrogenophaga, Chitinophagaceae, and Lentimicrobiaceae all increased, which may be responsible for the degradation of refractory organics in the oxic and anaerobic zones. The functional gene analysis indicated that the adaptation of microbial communities was probably related to cell-to-cell communications and the transportation of molecules across the cell membrane. The microbial community and functional gene analysis revealed the adaptation of the microorganisms to the industrial wastewater. This study provides new insights into the ICME to enhance the biodegradability of electroplating wastewater for A2O treatment.

An integrated full-scale system for the treatment of real ship domestic wastewater: Shore-test experiments

With the increasing number of ocean-sailing ships, the pollution of the oceans' water caused by the discharge of ship wastewater has become one of the serious concerns for the whole world. Most of existing ship wastewater treatment studies were carried out in bench/pilot-scale and cannot meet the latest discharge standards of International Maritime Organization (IMO) and China. To overcome those barriers and prepare for the onboard test, we evaluated the hydraulic retention time (HRT) variations (10.5-12 h) for treating low COD/TN ship wastewater by a full-scale oxic-anoxic micro-sludge membrane biofilm reactor (O-AMSMBR) system. The full-scale O-AMSMBR achieved over 82 % removal of chemical oxygen demand (COD) and 76 % removal of total nitrogen (TN) from a ship wastewater with continuous operation at a HRT of 10.5 h. Although anoxic membrane biofilm partly compensated for the deterioration of TN removal in performance of the aerobic sludge, the effluent TN concentrations still cannot meet IMO discharge standards at HRT as low as 9 h due to the inhibition of simultaneous nitrification and denitrification (SND) by low HRT and C/N. Wavelet Neural Networks (WNN) was used to explore the removal mechanism under HRT variations. Simulation results show that HRT andinfluent pollutant’s concentration are the two most sensitive factors for COD and TN removal in daily operation so special attention should be paid to the dramatic change of influent flow rate in ship sewage treatment operation. In particular, techno-economic analysis was conducted in this study to provides a baseline for developing economic options for ship wastewater treatment in practice.

Improved Biological Phosphorus Removal under Low Solid Retention Time Regime in Full-Scale Sequencing Batch Reactor

Enhanced biological phosphorus removal (EBPR) is an obscure but economical and helpful technology for removing phosphorus biologically from wastewater. A 3-MLD capacity pre-anoxic selector-attached sequencing batch reactor (SBR) treated municipal wastewater from the residents of IIT Roorkee. The treatment in the plant satisfied the effluent discharge standards in all respects except phosphorus, observed during an intensive two-year study. An elaborated 80-day study was performed to enhance and improve the plant’s performance in terms of phosphorus removal specifically, with run 1: solid retention times (SRT) reduced from 56 to 20 days (t = 35 d), run 2: lowering the diffuser’s running time from 15 min to 10 min in anoxic cum anaerobic selector chambers (dissolved oxygen (DO) concentration reduced to &lt;0.15 mg/L) along with reducing SRT to 15 days (t = 25 d), and run 3:intensive reduction in SRT to ≤10 days (t = 20 d). During run 3, the increment in the enhanced biological phosphorus removal (EBPR) efficiency was three times that of the initial run (ηmax~65%) with a readily biodegradable chemical oxygen demand to total phosphorus ratio (rbCOD/TP) of 7.8. The 16SrRNA sequencing revealed the microbial community structure before and after the changes in SRT and EBPR efficiencies, to correlate the biochemical processes and functional organisms.

Efficiency assessment of 3.2MLD MBR based sewage treatment plant of IFFCO township Aonla, Bareilly, Uttar Pradesh, India

Increasing urbanization and industrialization is continuously putting a pressure on the ground and fresh water resource in form of quality and quantity. Therefore water recycling through wastewater treatment is the need of the present hour. Therefore in the present study the efficiency of the 3.2MLD sewage treatment plant (STP) based on membrane bioreactor technology (MBR) located in Indian Farmers Fertilizer Cooperative Limited (IFFCO) township Aonla, Bareilly, Uttar Pradesh, India was studied. The plant was recently commissioned on 10th of June 2022. The plant shows highest efficiency for turbidity (98.6%) followed by total suspended solids (TSS) (95.7%), chemical oxygen demand (COD) (89.0%), iron (86.7%), and biochemical oxygen demand (BOD) (85.0%). The efficiency for the rest of the parameters is below 50%. The MBR based STP is working efficiently as the values of parameters in treated water is within the discharge standards of central pollution control board (CPCB) listed in The Environment (Protection) Rule, 1986. One of the major problems of MBR based STP reported in literature is membrane fouling which is also rectified in the current treatment plant by using sodium hypochlorite for membrane cleaning.

A qualitative of stable symptomatology for patients with schizophrenia: do they have adequate post-discharge rehabilitative resources?

Many patients diagnosed with schizophrenia face obstacles to rehabilitation and discharge into the community, particularly with regard to the way resources are structured. Clarifying the difficulties will help health care providers address rehabilitation shortcomings. Semistructured in-depth interviews and participatory observations were conducted in various locations (family home, hospital ward, outpatient clinic, and on the street) with families, social workers, doctors, nursing staff, and patients with schizophrenia. These patients met the medical facility’s hospital discharge standards and either had not been discharged or had been discharged within two weeks of meeting the discharge criteria. This study explores the complex and interdependent role of social differences in the rehabilitation of patients with schizophrenia after acute treatment. The study identified five topics related to structural difficulties in resources for the rehabilitation of patients diagnosed with schizophrenia: (1) the role of policy; (2) inadequate facilities and responsibilities; (3) rejecting communities; (4) difficult families; and (5) the threat of stigma. The rehabilitation of patients diagnosed with schizophrenia is a systemic problem. Systemic rehabilitation policies and integrated social support would be more conducive to the rehabilitation of patients. Perhaps cognitive remediation therapy or the Assertive Community Treatment (ACT) Model could benefit individuals with complex disorders.

How do firms respond to the tighter COD discharge standards? Evidence from the pulp and paper industry in China

ABSTRACT The chemical oxygen demand (COD) emissions from the pulp and paper industry in China have declined continuously since the tighter COD discharge standards were implemented in 2008. Using firm-level data from 2003 to 2013, we investigate how China’s pulp and paper firms would respond to the tighter COD discharge standards with a difference-in-differences design. We find that the tighter COD discharge standards have significant causal effects to induce the pulp and paper firms to reduce their COD emissions primarily through adopting cleaner production. However, the effectiveness of the tighter COD discharge standards depends on monitoring and enforcement activities as well as other regulations accompanying with the tighter COD discharge standards, all of which have become strengthened since China’s 11th Five-Year-Plan (FYP, 2006–2010). While strengthened environmental regulations since the 11th FYP are from the top leadership of the Chinese government in order to deal with the increasing environmental degradation, the underlying driving force of the strengthened environmental regulations is from the household demand for better environmental quality as income increases. This study enriches literature not only on firms’ responses to environmental regulations in developing countries but also on environmental regulations and technology adoption as well as environmental enforcement and compliance.

Efficient and Superstable Mineralization of Toxic Cd2+ Ions through Defect Engineering in Layered Double Hydroxide Nanosheets

Water and soil pollution caused by toxic cadmium ions (Cd2+) is a serious threat to animals, plants, and human health. Discovering low-cost mineralizers which can efficiently and stably immobilize Cd2+ ions is therefore imperative for wastewater treatment and soil remediation. In this work, we report the successful development of a novel mineralizer for Cd2+ ion capture. A magnesium–aluminum layered double hydroxide (MgAl-LDH) with a monolayer structure (MgAl-mono) was first prepared and then calcined at 350 °C for 4 h to produce a defective MgAl-mono-350. MgAl-mono-350 offered a very high Cd2+ removal capacity (1385.5 mg/g at 25 °C) and the ability to reduce the concentration of Cd2+ in aqueous solution from 100 ppm to less than 50 ppb in 15 min (meeting the discharge standard of industrial wastewater). Detailed characterization and computational studies revealed that MgAl-mono-350 possessed abundant oxygen defects, thereby enabling superstable mineralization of Cd2+ via isomorphous substitution process,and the Cd2+ ions are immobilized in the generated CdAl-LDH structure. MgAl-mono-350 also offered outstanding selectivity for Cd2+ ions over other common ions. This work demonstrates the potential of defect-engineered LDH materials for the selective removal of heavy metals from polluted water.

Assessment of the impacts of selected physicochemical and bacteriological parameters of wastewater (hospital effluents) from the University teaching hospital of Butare on the surrounding environment

Physicochemical and bacteriological properties are used to assess the quality of wastewater before discharge into the surrounding environment. This presented study was carried out to determine the contamination of effluents from the University Teaching Hospital of Butare. The results showed that the mean values such as 185 ± 7.07 mg/L, 1816 ± 2.83 mg/L, 335 ± 4.24 mg/L, 150.66 ± 2 mg/L, 269 ± 13 mg/L, and 4.19 ± 0.41 mg/L for EC, TDS, TSS, BOD, COD, and phosphates in the treated effluents, exceeded the permissible limits of WHO standards for wastewater discharge in the surrounding environment. In the case of heavy metals, a higher concentration of cadmium (0.29 ± 0.04 mg/L) was observed out of the allowed limit of WHO standard, whereas those for manganese (0.02 ± 0.01 mg/L) and zinc (0.16 ± 0.04 mg/L) were within the stipulated limit. Lead, iron, and chromium were not detected in CHUB treated effluents. Although CHUB treatment plant showed higher treatment efficiency, including 99.2%, 99.9%, and 92.9%, the recorded mean values showed higher abundance (7 × 106 Cfu/100 mL of TC, 6 × 105 Cfu/100 mL, and 5 × 107 Cfu/100 mL) of TC, FC, and E.coli in treated CHUB effluents. The proper treatment of CHUB effluent should be ensured before it is discharged into the environment.

Recovery of fluoride from spent cathode carbon block by combustion combined with water leaching process

Spent cathode carbon blocks (SCCBs) is a kind of hazardous waste that can be harmful to the environment. In this study, a process of high-temperature combustion combined with water leaching was explored to dissociate toxic substances from SCCB and recover valuable components. Combustible components in SCCB can be converted into useable heat energy. The combustion parameters and water leaching process were optimized, and the transformation trend of important components was explained. According to the experimental findings, under optimal conditions, the combustion weight loss rate of SCCB reaches 81.5%, and the defluorination rate reached 88.2%. The toxic leaching concentration of fluoride from the treated residue was reduced to 49 mg L−1, in line with the safe discharge standard. The characterization results showed that the final recovered product was highly similar to its analytical reagent counterpart. This treatment process has the environmental benefits of secondary resource recycling and can effectively reduce the negative impact of SCCB on the environment.