Chemical Oxygen Demand Values Research Articles

Effect of Water Exposed to Electric Current on Gamete Quality of Rainbow Trout (Oncorhynchus mykiss) and Water Parameters

Electrofishing is a widely preferred method in freshwater. Freshwater conducts electric current at low levels. Therefore, a relatively high voltage electric current is applied in these waters. In this study, the effects of changes in the structure of the water after the electric current applied to the water on gamete quality and embryo-larvae survival rates were investigated. Water samples were collected from the central region of the tank (N), as well as from the positive (+) and negative (-) poles following the application of an electric current to the well water at 165 volts and 3 mA for durations of 15 and 30 minutes. Sperm kinematic velocity parameters, fertilization and hatching rates were determined to be at the highest level in the group where electric current was applied for 30 minutes and water samples were taken from the middle of the tank, 30 (N), were used (P<0.05). Furthermore, it was observed that the Chemical Oxygen Demand value was one of the values lowest in the groups where sperm motility results were found to be the highest (P<0.05). Regardless of the duration of electric current application, it was found that the dissolved oxygen value of the water samples collected from the positive poles was similar to the control group, but higher than the negative poles. In conclusion, the application of electric current resulted in variations in both the sperm kinematic parameter values and the water parameters among the samples collected from different poles. However, there was no statistically significant difference in fertilization and hatching rates between the groups (P>0.05).

Homojunction-Incorporated Oxygen Vacancy Functionalized Spherical TiO2 Nanocrystals for the Electrochemical Detection of Chemical Oxygen Demand.

Chemical oxygen demand (COD) is a critical criterion for the analytical assessment of the degree of organic contaminants in an aqueous system. Typically, toxic and expensive reagents are employed in standardized COD analysis methods, leading to secondary pollution. In this work, we developed a rapid electrochemical method for COD detection based on the oxidation of hydroxyl radicals for organics in water by using oxygen vacancy doped anatase/rutile-TiO2 nanoparticles as electrooxidation catalysts. Homojunction interface generated increasing oxygen vacancies for enhancing electron-transfer rate and accelerating H2O oxidation to substantially improve ·OH yield. Oxygen vacancy further increased the oxygen evolution potential of the material. Initially, glucose was chosen as a standard analyte to evaluate electrochemical responses, and water from urban wastewater treatment plants was assessed as real samples subsequently. Excellent analytical characteristics were achieved with the A/R-TiO2 sensor under the optimal conditions, exhibiting a linear range from 1 to 300 mg L-1 and detection limit of 0.1 mg L-1 COD. The estimated COD values obtained from the samples were highly consistent with those determined using the conventional standard dichromate method. We have presented a fast, cost-effective, and ecologically sustainable method that outperforms the standard COD analysis method and holds great potential for the accurate determination of COD and boasts high detection sensitivity and a broad linear range.

Optimization, Purification and Characterization of Lipase from Streptomyces sp. A3301, with Application of Crude Lipase for Cooking Oily Wastewater Treatment

Streptomyces sp. A3301, which produces lipase isolated by Panyachanakul et al. [1]. This optimization was done for the subsequent purification and characterization of the biological lipase produced by the isolate. The results showed that the strain produced lipase with a maximum activity of 321 U/mL using the optimal medium and conditions (1.5 % (w/v) xylose and 2 % (w/v) yeast extract, pH 7.0 at 30 °C, 150 rpm for 3 days). The specific activity of the purified lipase was 27,000 U/mg, which was 544 times the pre-purification level, based on hydrophobic chromatography. After ion-exchange chromatography, the specific activity was 5,600 U/mg, which was 113 times the pre-purification level, with a single-peak purification profile. The purified lipase had a single band based on SDS-PAGE analysis and the molecular mass was 45 kDa. The optimum temperature and thermo-stability of A3301 lipase were 60 and 30 - 55 °C, respectively. The optimum pH of the purified enzyme was pH 9.0, and the enzyme was stable in the pH range of 8.0 - 9.0. The purified lipase was stable in acetone, chloroform and toluene, with a high relative activity of 63 - 76 %. The immobilized strain was then applied to oily-wastewater treatment. The strain can remove oil and grease in synthetic wastewater containing oil at 1 - 3 % (v/v), with removal rates of 100, 99.82 and 99.68 %, respectively, after incubation for 6 days. It was then applied to oily-wastewater treatment from a restaurant, achieving the highest degradation rates of 98.53 % after treatment for 6 days. In addition, it also affected the Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) values decreasing. HIGHLIGHTS Optimization of lipase production by Streptomyces A3301. Purification and characterization of the lipase produced by the Streptomyces A3301. Application of the immobilized Streptomyces A3301 strain in the treatment of oily cooking wastewater. The immobilized Streptomyces A3301 strain has the capability to remove oil and grease in both synthetic mediums and restaurant wastewater. GRAPHICAL ABSTRACT

Evaluation of Integrated Anaerobic/Aerobic Conditions for Treating Dye-Rich Synthetic and Real Textile Wastewater Using a Soda Lake Derived Alkaliphilic Microbial Consortia

Textile industry wastewater (WW) has intense color, high chemical oxygen demand (COD), pH, and salinity, making it challenging for conventional treatment. Soda lakes, with high alkalinity and salinity, host diverse microbes capable of textile dye degradation. This study evaluated anaerobic/aerobic reactors using alkaliphilic microbial consortia from Lake Chitu, an Ethiopian soda lake, for treating synthetic and real textile WW. The experimental setup consisted of a first-stage anaerobic reactor followed by a second-stage aerobic reactor, operating continuously with a predetermined flow rate and hydraulic residence time. After evaluating synthetic WW, real textile WW was collected in two batches (rounds I and II). The treatment setup removed 99% of the dye color for synthetic WW, 98% for round I, and 96% for round II. COD removal was 87% for synthetic WW, 86% for round I, and 93.37% for round II. TKN removal reached 90% for synthetic WW, 91% for round I, and 96% for round II at a steady state. Residual COD and TKN values met the final effluent discharge standards. GC–MS and IR analyses revealed that dyes were broken down into intermediate organic compounds under anaerobic conditions and further degraded into smaller molecules under aerobic conditions. This integrated reactor approach effectively removes dyes and enhances COD and TKN removal. The study’s novelty lies in evaluating both synthetic and real textile WW using integrated reactors under alkaline conditions in a continuous process, inoculating alkaliphilic consortia, without pre-enrichment or external nutrient addition to real WW. The study provides insights into the effectiveness of alkaliphilic microbial consortia derived from soda lakes for treating textile WW using integrated reactor conditions. Reactor microbiome characterization is needed to further explore microbial diversity and community structure.

Start-up phase performance evaluation of a pilot-scale sequential anaerobic-aerobic hybrid algal-bacterial suspended growth reactor for the domestic wastewater treatment

This study evaluated the start-up phase performance of an 80-cubic-meter pilot-scale anaerobic-aerobic hybrid algal-bacterial reactor treating real domestic wastewater operated at 24 h hydraulic retention time. The aerobic chambers of the reactor were inoculated with heterotrophic bacterial biomass and mixed microalgal culture. Blue light-emitting-diode (LED) lights were provided in the aerobic chambers to facilitate algal photosynthesis. The influent chemical oxygen demand (COD), total nitrogen (TN), and phosphorus (P) values were 241 ± 45 mg/L, 26.8 ± 4.2 mg/L, and 6.7 ± 0.9 mg/L, respectively. After thirty days of operation, the effluent COD, TN, and P values were observed to be 26.7 ± 6.5 mg/L, 15.6 ± 0.73 mg/L, and 4.45 ± 0.16 mg/L, respectively. The sludge volume index of the mixed liquor was 43 mL/g, indicating high settleability. During the operation, an increase in the chlorophyll to biomass ratio was observed, which implies that the algal-bacterial symbiosis might have played a role in simultaneous carbon and nitrogen removal from the domestic wastewater.

Spatial Variation of Physico-chemical and Microbial Parameters in Groundwater of Selected LGAs of Akwa-Ibom State, Nigeria

Physico-chemical and microbial parameters of groundwater are useful indicators in monitoring the progress of Goal 6.3 of Sustainable Development Goals (SDGs). The study evaluated the spatial variation of physico-chemical and microbial parameters in groundwater of selected LGAs of Akwa-Ibom State, Nigeria in line with SDGs. A total of twenty (20) groundwater samples were collected from boreholes at different locations within Uyo, Itu, Ibiono Ibom and Ibesikpo Asutan Local Government Areas of Akwa-Ibom State. The boreholes were selected at random. Sterilized and pre-labelled water sampling bottles were used in collecting representative water samples to prevent contamination. Physico-chemical parameters sensitive to environmental changes such as temperature, pH and electrical conductivity were measured in-situ. Sampling and analysis followed guidelines specified by the American Public Health Association, (2012). Chemical analysis was carried out at the Geospectra Laboratory in Port Harcourt, Rivers State of Nigeria. Results showed that the groundwater condition ranged from acidic and slightly weakly acidic in Uyo and Ibiono Ibom but slightly alkaline in Itu. All the heavy metals analysed were within the permissible limits specified by WHO (2018) and NSDWQ (2015) in drinking water. The average values of total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), faecal coliform and total coliform in Uyo, Itu, Ibiono and Ibesikpo were 57.4 mg/L, 40.1 mg/L, 97.0 mg/L, 1032 and 1542.3 MPN/100ml, 54.3 mg/L, 51.6 mg/L, 110 and 47, 20.5 mg/L, 35.7 mg/L, 78.5 mg/L, 28.8 and 82.5 MPN/100ml, and 184 mg/L, 42.8 mg/L, 94.3 mg/L, 130 and 280 MPN/100ml respectively. The values of pH, BOD, COD, faecal and total coliforms were found to be above the permissible limits. Faecal and total coliforms, which indicate recent contamination, are high in Uyo and could be attributed to urbanisation with its consequent sewage management issues and increased animal droppings. There is a need for proper sewage management within the city.

Tratamiento químico de vinaza de caña de azúcar con peróxido de hidrógeno

[Introduction]: Vinasse is generated as a residue in the production of ethanol by fermentation-distillation of molasses/sugar cane juice, at a rate of 13 L/L of ethanol. It is an acid liquid, brown in color, characterized by high mineralization and Chemical Oxygen Demand (COD) values of up to 150 000 mg/L, being highly polluting. [Objective]: The objective of this research was to evaluate a vinasse treatment process with hydrogen peroxide as a source of hydroxyl radicals at laboratory scale. [Methodology]: The vinasse samples, from different distilleries in the province of Tucumán, were characterized following standardized techniques of Standard Methods. The oxidation tests were carried out with different peroxide/vinasses ratios, in a semi-batch reactor, under ambient conditions, measuring COD as an indicator parameter of the treatment. [Results]: After 5 days, an 85 % decrease in COD and an increase in the Biodegradability Index were achieved. The kinetics of the oxidative reaction was first order with respect to COD, with an apparent rate constant of 0.3694 1/day. [Conclusions]: Although the COD values allowed by local regulations (250 mg/L) were not reached, the proposed treatment is encouraging due to its simplicity, representing a potential option to the environmental challenge represented by vinaze in Latin America.

Biomass microcrystalline cellulose based solar evaporator with aligned channels for clean water and electricity co-generation

Solar-driven interfacial evaporation co-generation (SDIE-CG) technology can effectively solve problems such as low latent heat utilization in the evaporation process, which provides a reliable solution to the problem of hydropower shortage in remote areas. Herein, we report a tea residue microcrystalline cellulose (TMCC) aerogel (abbreviated as TCA), in which TMCC is regenerated by dissolution through the co-solvent method, and microcrystalline cellulose is rearranged by the directional slow freezing technique to get a TCA with a directional aligned pore structure, resulting in a good mechanical and salt-resistant property. Due to the internal doping of carbon black particles, the TCA has an average ultra-high absorbance of 97.46 %. The evaporation rate of TCA is up to 3.066 kg m−2h−1 under 3 kW m−2 illuminations. The maximum output voltage of the TCA is 44.801 mV under 2 kW m−2 illuminations through the introduction of a suitable wind-assisted hydropower generation device. In addition, the TCA can effectively purify the wastewater containing traditional Chinese medicine, and the chemical oxygen demand (COD) value in wastewater shows a significant decrease after treatment. It is worth noting that TCA can maintain structural integrity and stable evaporation performance in saltwater under extreme pH conditions (2<pH<11), and has potential application value in water treatment and cogeneration.

Study on Non-Point Source Pollution Prevention and Control System in Nansi Lake Basin Based on System Dynamics Approach

Agriculture, as an important activity on which human beings depend for their livelihood, brings serious environmental problems while meeting the needs of human survival, among which agricultural non-point source (NPS) pollution is one of the most urgent environmental problems. This study quantitatively assessed the loading characteristics spatial and temporal evolution patterns of two agricultural NPS pollutants, chemical oxygen demand (COD) and ammonia nitrogen (NH3-N), from 2010 to 2020 in the Nansi Lake Basin as an example, and constructed a system dynamics (SD) simulation model to simulate and analyze agricultural NPS pollution under different development and treatment scenarios, based on an investigation of the regional prevention and control strategy of agricultural NPS pollution and the technological system. The results show that the current status of agricultural NPS pollution load in the Nansi Lake Basin is poor, and the level of pollution load is high, showing obvious geographical differences. In terms of temporal changes, the pollution loads of the two pollutants showed a decreasing trend from 2010 to 2020, among which the pollution load of NH3-N showed the largest change. Spatially, the spatial distribution of each type of pollutant has some similarities, with smaller pollution loads in Jining and Zaozhuang and relatively larger pollution loads in Heze and Ningyang. The main source of COD pollution in the Nansi Lake Basin is rural life, with an emission proportion of 52.85%, and the main sources of NH3-N pollution from agricultural NPS pollution in the area are rural life and livestock and poultry farming, with emission proportions of 47.55% and 35.36%, respectively. Under the status quo continuum scenario, the pollution load values for COD are consistently higher than those for NH3-N, so the relative impact of COD is greater. In this study, the principles and methods of SD in system science are adopted to deal with the agricultural NPS pollution of Nansi Lake Basin, and the evolution of its behavioral characteristics are simulated, forecasted, and predicted, and policy experiments are conducted, with a view to providing references for the prevention and control of agricultural NPS pollution in Nansi Lake Basin and further research.

ZnO nanostructures grown from spent batteries: Ambient catalytic aspects and novel mechanistic insights

The present work includes a facile and economic microwave assisted hydrothermal synthesis of Zinc Oxide (ZnO), Diethylene Triamine Pentaacetic Acid (DTPA) stabilized Zinc Oxide (ZD) and DTPA stabilized Silver doped Zinc Oxide (ZAD) nanostructures using Zn from spent alkaline batteries. The synthesised nanostructures were well characterised using electronic, vibrational and X-Ray spectroscopic techniques as well as thermal and microscopic techniques revealing the successful stabilisation of DTPA in ZD and doping of Ag in ZAD. The Fourier Transform Infrared Spectroscopy (FTIR) spectra showed peaks characteristic to the presence of ZnO in the fingerprint region and those to the presence of DTPA. The X-Ray Diffraction Spectroscopy (XRD) pattern of ZnO, ZD and ZAD indicated the hexagonal wurtzite structure of ZnO and face centred cubic metallic Ag in ZAD. The Transmission Electron Microscopy (TEM) images revealed rod shaped morphology for ZnO and spherical morphologies for ZD and ZAD. The nanostructures proved to be efficient catalysts to achieve 100 % degradation of Malachite Green, Crystal Violet and Reactive Blue-21 and their binary mixtures under ambient conditions in presence of Hydrogen peroxide (H2O2). ZAD exhibited relatively rapid degradation with rate constants 0.754 min−1, 0.187 min−1 and 0.0150 min−1 for MG, CV, and RB-21 respectively as well as 99 % reduction in Chemical Oxygen Demand (COD) value of the dye solutions. Scavenging studies and Electron Paramagnetic Resonance (EPR) studies using different spin trapping agents revealed the involvement of singlet oxygen species, hydroxyl radicals (OH.) and superoxide radicals (O2.-) in the degradation process. This work aligns with Sustainable Development Goals 6, 12 and 13.

Assessment of water quality and source apportionment of pollution in a tropical river in eastern India: A study utilizing multivariate statistical tools and the APCS-MLR receptor model.

The Mundeswari River, an ecologically distressed river in eastern India, has been subjected to water quality deterioration largely due to anthropogenic activities in its vicinity. This study aimed to comprehensively evaluate the current state of pollution in the river and assess the appropriateness of river water for irrigation, given its extensive use for agricultural purposes. Monthly water quality monitoring was undertaken at four distinct sampling sites (SP1-SP4) over a two-year period (2020-2022), considering seventeen water quality parameters. This research employed principal component analysis/factor analysis (PCA/FA) and absolute principal component score-multiple linear regression (APCS-MLR) receptor modelling. These methodologies were used to discern and quantify potential sources of pollution influencing the water quality of the Mundeswari River. The study revealed that the water quality of the Mundeswari River was most degraded during the pre-monsoon season. Among the four sampling sites, SP3 exhibited the highest level of pollution with mean biochemical oxygen demand (BOD) and chemical oxygen demand (COD) values of 5.36mg/L and 44.72mg/L, respectively. According to the one-way analysis of variance (ANOVA), there was considerable spatial and seasonal disparities (P < 0.05) in most water quality parameters. The PCA/FA extracted four latent pollution sources, accounting for 81.5% of the total variance. The primary factors influencing the quality of river water are natural weathering processes, discharge of domestic effluent and waste, and agricultural runoff. The APCS-MLR receptor model further revealed that agricultural drainage factors and the discharge of domestic effluent and waste had a greater impact on the Mundeswari River. The investigation concluded that the mean values of all indicators for irrigation suitability were below the defined threshold limits, indicating that the water of the studied river appears suitable for irrigation. The outcomes of this study may significantly contribute to the formulation of sustainable strategies for the ecological rejuvenation of the Mundeswari River.

Reducing sludge formation by enhancing biological decay of biomass: a mathematical model

Abstract We investigate a model for an activated sludge process that contains a chemical reactor unit attached to a bioreactor. Inside the chemical reactor unit, a process takes place which increases the decay coefficient of heterotrophic biomass. This mimics a number of experimental techniques which are used to decrease the mass of sludge. Such techniques are of growing interest as the activated sludge process produces large volumes of sludge; the costs associated with its disposal are significant. Our primary interest is to investigate how the operation of the chemical reactor unit changes the steady-state concentrations of both the total suspended solids within the biological reactor and the chemical oxygen demand in the effluent stream. The operation of a chemical reactor unit always increases the value of chemical oxygen demand in the effluent stream. The behaviour of the total suspended solids is more complicated; in some cases, the operation of the CRU increases the total suspended solids. For a fixed value of the chemical oxygen demand in the influent stream, we show that both the percentage reduction in the total suspended solids and the chemical oxygen demand in the effluent stream are increasing functions of the soluble substrate in the feed. The same trends occur when the influent composition is fixed, and the disintegration rate inside the chemical reactor unit is increased. This leads to dichotomic behaviour, decreasing the total suspended solids increases the chemical oxygen demand in the effluent stream. There are two consequences of this behaviour. Firstly, there are some waste streams that can not be cleaned using the process configuration considered in this paper. Secondly, the imposition of a target value for the chemical oxygen demand in the effluent stream imposes a maximum achievable reduction in the total suspended solids in the biological reactor. Higher reductions can not be achieved without causing the chemical oxygen demand in the effluent stream to exceed the target value.

Long-term trends in dissolved oxygen and environmental parameters in Jinhae Bay, Korea: A 25-year analysis (1997–2021)

In recent decades, global oceanic dissolved oxygen (DO) levels have been consistently declining, leading to a notable increase in hypoxic zones. However, comprehensive information on the current trends of DO in Jinhae Bay remains scarce. This study investigated the long-term variations in bottom dissolved oxygen (DO) in Jinhae Bay, specifically focusing on recurring occurrences of oxygen-deficient water (ODW) in August, coinciding with the lowest average DO levels with the most stratified water. ODW events predominantly manifested in the inner bay, while the outer bay exhibited fewer instances due to robust water exchange processes. Analysis of the Low DO group revealed higher surface temperature and salinity, indicating diminished oxygen solubility compared to the High DO group. Lower Chemical oxygen demand (COD) and chlorophyll-a (Chl-a) values in the Low DO group suggested enhanced bacterial decomposition and subdued photosynthesis, in contrast to the High DO group. Over the last 25 years, Jinhae Bay has experienced a discernible decline in bottom DO concentrations. Contrastingly, surface temperature has exhibited a consistent upward trend, notably accelerating in the last 12 years, indicating reduced oxygen solubility. Notably, a substantial reduction in bottom DO levels was observed in the outer bay, previously considered less susceptible to hypoxic conditions. Furthermore, a concurrent decrease in pH highlights the urgency for a comprehensive investigation encompassing both summer hypoxia and seawater acidification, crucial for protecting Jinhae Bay's ecosystem from further deterioration.

Potential of Eco-enzyme Averrhoa bilimbi L. Fruit as an Innovation in Tempeh Wastewater Treatment in Plaju District, South Sumatra

Tempeh home industries have been established in residential areas, one of which is in the assisted village of PT Pertamina Internasional RU III Plaju Factory, Palembang, South Sumatra. Eco-enzyme is one of the methods for processing and reducing pollutant organic matter in liquid waste. This study aims to determine the eco-enzyme characteristics of Averrhoa bilimbi L. fruit and exploit its potential to reduce chemical oxygen demand (COD), total suspended solid (TSS), and total dissolved solid (TDS) in tempeh wastewater. Eco-enzymes are characterized by measuring pH, COD, TSS, TDS, and most probable number (MPN). The reduction in COD, TSS and TDS of tempeh wastewater was observed using a simple bioreactor which was treated with the addition of 10% eco-enzyme (three replicates) and without the addition of eco-enzyme (control). The characterization results showed that the eco-enzyme of A. bilimbi L. fruit had a pH of 1.84, COD of 85.33 mg/L, TSS of 440 mg/L, TDS of 15,800 mg/L, protein concentration of 0.459 U/mg, and MPN value of 0.03 CFU/100 mL. The COD value of tempeh liquid waste can be reduced from the initial COD of 256 to 154.67 mg/L. The TSS value of tempeh wastewater decreased by 60% from the initial value of 4,000 mg/L. It takes 18 days to reduce the TSS content below the quality standard. The TDS value of tempeh liquid waste can be reduced by 70% from the initial TDS of 7,333.33 to 1,666.67 mg/L.

Analysis of Chemical Oxygen Demand in Barrel Finishing Based on Reusing Water Resource of Grinding Fluid.

To explore the sustainable development of grinding fluid in barrel finishing, the idea of water resource reuse in grinding fluid has been proposed. The influence of the graphene oxide (GO) and the sodium dodecyl benzene sulfonate (SDBS) as main components in the grinding fluid on the chemical oxygen demand (COD) was analyzed. Repreparing new grinding fluids by utilizing the water resources in grinding fluid after finishing will not cause a sharp increase in COD value. GO which absorbs SDBS can be taken away from grinding fluid by physical separation. It will decrease the COD value of grinding fluid. However, SDBS exists in the form of colloids in the grinding fluid and cannot be removed through physical separation, which also affects the COD value. Based on water quality indicators (the COD, pH, total hardness, metal aluminum, anionic surfactants, and total dissolved solids), the water quality index (WQI) of the reusing grinding fluid after finishing by the physical separation is significantly reduced. It indicates that reusing water resources in grinding fluid is a feasible way to reuse grinding fluid.

Research on Ammonium Removal from Wastewater by Adsorption and Ozonation Processes

With the ongoing amendment of the European Union legislation on the treatment of municipal wastewater, stricter requirements for the removal of pollutants are expected, which calls for the need for innovative wastewater treatment technologies. Our research was focused on the removal of ammonium nitrogen from municipal wastewater by nontraditional processes based on the use of adsorption processes on zeolite (ZEO) and ozone. Adsorption, adsorption-regeneration, and adsorptive ozonation processes were applied. All processes were carried out in a completely stirred reactor (CSR) and a jet-loop reactor (JLR) with external recirculation of the reaction mixture. Experimental measurements were carried out with real municipal wastewater after mechanical treatment. The best results were achieved in the adsorption-regeneration process, which was implemented in a current loop reactor. An average ammonium nitrogen removal efficiency of 53.1% was obtained by adjusting the pH value to 10.0. Average values of 46.2% and 49.2% for chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies are an added value of the process. The values of ammonium nitrogen, COD, and TOC removal efficiencies in individual cycles confirm the high stability of the process.

Nonlinear Effects of Agricultural Technology on Sustainable Grain Production in China

Grain production is an important element of the United Nations Sustainable Development Goals, regarding livelihoods and social stability. This article uses data on agricultural technology, social factor and grain production in China from 2011 to 2022, and uses the Generalized Additive Model (GAM) to deeply explore the nonlinear impact of agricultural technology and social factor on grain production. The results of the study show that (1) China’s grain output is generally on a growing trend, but the growth rate is declining and fluctuating significantly. There is a significant difference in grain production before and after the COVID-19 epidemic. Moreover, the output in the northern region is significantly higher than that in the south. (2) Except for Consumption expenditure per capita, all other agricultural technology and social factor variables are positively correlated with grain out. (3) The impact of agricultural technology and social factor on grain output shows significant non-linear characteristics, and its impact effect varies in different intervals. Specifically, When the value of the agricultural meteorological observation service station is 20-25, the effective irrigation area is greater than 1800, consumption expenditure per capita greater than 17000 and the total sowing area of crops is 7500, it can significantly increase grain yield. On the contrary, if the emission value of chemical oxygen demand exceeds 130, it has a significant inhibitory effect on grain yield. Furthermore, the effect on grain yield peaks when the total power of agricultural machinery, GDP, and the number of unemployed people in cities approach 3000, 10000, and 20, respectively. The results of the study provide an important basis for optimizing the allocation of agricultural resources and enhancing the efficiency of grain production. Finally, some practical policy recommendations are put forward.

Economic valuation and characterization of heavy metal contamination in Dal Lake Srinagar, Kashmir, India

Dal Lake, the world-famous tourist attraction has been polluted by allochthonous and autochthonous sources, as a result the heavy metal (HMs) concentrations within the water body has reached the toxic levels which is endangering the lives of the people. A study was carried out during the year 2021 (i) to determine the concentration of HMs (molybdenum: Mo, arsenic: Ar, cadmium: Cd, lead: Pb) at the four designated sites of Dal Lake, and (ii) a public survey (400 persons) involving economic valuation of water body in terms of recreational use and other benefits. The highest values of biological oxygen demand (BOD) and chemical oxygen demand (COD) within the Dal Lake were recorded at site A, which were 31 ± 1.10 mg/l and 76 ± 0.64, respectively. Similarly, maximum nitrate nitrogen was found at site A (865 ± 0.86 μg/l). The highest value of Pb was reported (6.828 ± 0.003 ppb) from site A whereas, the lowest from site B (2.492 ± 0.002 ppb). The mean values of Mo concentrations (in ppb) were found to be 2.538 ± 0.002, 1.703 ± 0.003, 3.627 ± 0.004 and 4.787 ± 0.002 at the four sites respectively. The observed values of HMs (in ppb) were much higher than the permissible values (WHO, 2006) and those reported earlier. A huge amount of money (Rs 16,18,66,000/) is being generated from the floating gardens of Dal Lake, calculated by TCM and CVM methods. During the survey, 68 % of people showed a willingness to pay (WTP) for the restoration of the Dal Lake and improved services (mean value: Rs 62,852.20/). Thus, the monitoring and assessment were done to find out how the Dal Lake contributes to the economy of the state by way of its different services and the major attraction for tourists besides the possible reasons for the deterioration of water quality, in order to find a long-lasting solution for the sustainable conservation of Dal Lake.

Oxidation and mineralization rates of harmful organic chemicals in hydroxyl radical induced reactions

In most of advanced oxidation processes (AOPs) used to destroy harmful organic chemicals in water/wastewater hydroxyl radical (•OH) reactions oxidize (increasing the oxygen/carbon ratio in the molecules) and mineralize (transforming them to inorganic molecules, H2O, CO2, etc.) these contaminants. In this paper, we used the radiolysis of water to produce •OH and characterised the rate of oxidation and mineralization by the dose dependences of the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) content values. Analysis of the dose dependences for 34 harmful organic compounds showed large differences in the oxidation and mineralization rates and these parameters are characteristic to the given group of chemicals. E.g., the rate of oxidation is relatively low for fluoroquinolone antibiotics; it is high for β-blocker medicines. Mineralization rates are low for both fluoroquinolones and β-blockers. The one-electron-oxidant •OH in most cases induces two − four-electron-oxidations. Most of the degradation takes place gradually, through several stable molecule intermediates. However, based on the results it is likely, that some part of the oxidation and mineralization takes place parallel. The organic radicals formed in •OH reactions react with several O2 molecules and release several inorganic fragments during the radical life cycle.

Hydrogeochemical characteristics, driving factors, and health risk assessment of karst groundwater in Southwest Hubei Province, China.

In South China, karst groundwater is an important water resource for industrial, agricultural, and drinking purposes. However, karst aquifers are highly vulnerable to pollution, leading to deteriorating karst groundwater quality and posing potential health risks to local residents. In this study, 22 groundwater samples were collected from a karst aquifer in the southwestern part of Hubei Province. The hydrogeochemical characteristics and their controlling factors were examined, and the potential health risks associated with groundwater pollutant concentrations in karst groundwater were assessed. The results showed that the groundwater is slightly alkaline with low chemical oxygen demand values, indicating good water quality. The groundwater facies type was identified as HCO3-Ca at most sample spots, showing low total dissolved solids concentrations. Substantial spatial variations in Na+, CO3 2-, and NO2 - concentrations were found, whereas spatial variations in the K+, Ca2+, Cl-, HCO3 -, and F- concentrations were small. In addition, the dissolution of gypsum deposits and magnesium carbonate sedimentary rocks at sampling sites resulted in groundwater facies types of HCO3•SO4-Ca and HCO3-Ca•Mg, with low total dissolved solids concentrations. The karst groundwater chemistry in the study area was mainly controlled by water-rock interactions, as well as by the dissolution of gypsum deposits and magnesium carbonate sedimentary rocks at specific groundwater sampling sites. The groundwater Cl- concentrations were mainly affected by atmospheric precipitation. NO3 - was mainly derived from atmospheric precipitation, domestic sewage, septic tanks, and industrial activities, whereas SO4 2- was derived from atmospheric precipitation, sulfate rock dissolution, and sulfide mineral oxidation. These results highlight the absence of potential human health risks of NO3 - and F- to infants, children, and adults, as their concentrations are below the corresponding regional background values. In contrast, the potential health risks of Cl- cannot be ignored, particularly for infants. This study offers scientific guidelines for protecting and allocating local groundwater resources.