Intending to remove toxic graphene oxide (GO) from wastewater, LDH (layered double hydroxide) was employed to recover GO by adsorption method. The adsorption performance and the mechanism of LDH for GO have been systematically studied by diverse characterization technologies and methods. The relevant effects of solution pH (2-9), absorbent dosage (5-25mg) and the concentration of GO (20-160mg/L) were investigated in detail. The main driving force of GO condensation on LDH may be electrostatic interaction and hydrogen bonding, SEM, TEM, AFM, FT-IR and XRD analysis further confirmed this. XPS test shows that the adsorption process is carried out through C−O and O−C=O. We have got a high removal rate of 92% and an adsorption capacity of 1472 mg/g under an optimized conditions (pH = 3.0, equilibrium time = 6.0 h, dosage = 10mg, C0 = 160 mg/L). The analyses implied that LDH will be a very promising candidate for recovery of GO from wastewater.

In this study, laccase produced by the white rot fungus strain Pycnoporus sp. Y1 was used for the leather dyeing wastewater decolorization. The mediators including veratryl alcohol (VA), 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), hydroxybenzoic acid (HA), hydroxybenzotrizole (HOBT), and temperature, pH values, laccase concentration, and leather dyeing wastewater dilution ratio were all investigated in the experiments, and then four factors (mediators, temperatures, pH values, dilution ratios) were optimized by orthogonal experimental design. The optimal conditions for wastewater decolorization were obtained as follows: temperature of 50°C, pH 3.0, laccase concentration 4 U/mL, and the dilution ratio of 1-fold, the decolorization ratio could reach 58.42% in 10 min under the optimized conditions at last.

Sustainable energy legislation in the modern world is the primary strategy that has raised the benchmark for energy and environmental security globally. The rapid growth in the human population has led to rising energy needs, which are predicted to increase by at least 50% by 2030. Waste management and environmental pollution present the biggest challenge to developing countries. The improvement of energy efficiency while ensuring higher nutritional evacuation wastewater treatment plants (WWTPs) is a significant problem for many wastewater treatment plants. Some treatment techniques require high energy input, which makes them expensive to remediate water use. Pollutants like chemical pesticides, hydrocarbons, colorants (dyes), surfactants, and aromatic compounds are present in wastewater and are contributing to other problems. Israel consumes 10% of the global energy supply, significantly more than other countries. The lagoon and trickling filters are the most widely used technologies in South African WWTPs, where the electricity intensity ranges from 0.079 to 0.41 kWh.m-3 (Wang et al. 2016). Korea and India use almost the same energy (0.24 kWh.m-3). An estimated one-fifth of the energy used in a municipality’s WWTPs is used for overall public utilities, and this percentage is anticipated to rise by 20% over the next 15 years owing to expanding consumption of water and higher standards. In this review paper, we examined the potential for creating energy-self-sufficient WWTPs and discussed how much energy is currently consumed by WWTPs. The desirable qualities of microalgae, their production on a global level, technologies for treating wastewater with biogas and solar power, its developments, and issues for sustainable development are highlighted. The scientific elaboration of the mechanisms used for pollutant degradation using solar energy, as well as their viability, are the key issues that have been addressed.

China has a typical labour-intensive chemical fibre industry characterized by high energy consumption, severe pollution tendencies, and low resource utilization rate. The chemical fibre industry seriously harms the environment due to its small production scale, single product variety, low resource utilization efficiency, and weak technology strength. Investigating wastewater generated by chemical fibre production and improving the measurement uncertainty of monitoring factors are significant to chemical fibre wastewater treatment and environmental protection. A review of related literature on wastewater pollution in the chemical industry is conducted to summarize the types of wastewater hazards in the chemical fibre production process. An environmental monitoring uncertainty model is used to measure the wastewater monitoring uncertainty of a chemical fibre enterprise in Jilin City, Jilin Province in China. Findings show that the hazardous types of chemical fibre wastewater include polluting the surrounding environment, endangering human health, and destroying existing biodiversity. The monitoring quality reliability of the extended uncertainty model for the pH value, chemical oxygen demand, ammonia-nitrogen, and total phosphorous used in this case is superior to the direct chemical numerical detection quality. The monitoring uncertainty of chemical fibre wastewater can be further improved by perfecting the chemical fibre production process and the wastewater treatment process. Its environmental hazards can also be relieved by improving the environmental monitoring industry of wastewater and strengthening the R&D of related virtual instruments. This study can serve as a reference for enhancing the environmental monitoring quality of chemical fibre wastewater, compensating for the environmental monitoring errors, realizing the energy conservation and emission reduction of the chemical fibre industry.

This paper is aimed to investigate the oxidation ability of the bacteria (Thiobacillus thioparus, Z-2) and the biological oxidation mechanism and oxidation kinetics on the reduced inorganic sulphuric compounds in sodium-process desulphurization wastewater. Results showed that the Z-2 bacteria have high oxidation activity in the high-salt environment after acclimation, and the oxidation percentage of reduced inorganic sulphuric compounds reached 95% and the chemical oxygen demand (COD) reduced from 18000mg/L to 2000 mg/L in the high-salt environment. This showed that the Z-2 bacteria have strong salt resistance and high oxidation activity. In addition, ion chromatography analysis confirmed that Z-2 bacteria were beneficial for the oxidation of reduced sulphur. A biological oxidation model was constructed by measuring the enzyme activity of the oxidation process. The results indicated that direct and indirect oxidation processes were both involved in biological oxidation. The kinetic parameters of Vmax (21.38 µM/min) and Km (79.04 µM) were obtained through biological oxidation kinetic experiments.

Pollution is a critical environmental issue. Currently an enormous amount of wastewater and fresh concrete waste aggregates are being produced by the ready mix concrete industry throughout the world. The concrete washout water and excess fresh concrete aggregates are hazardous for disposal due to their high pH value (pH >12). Improper disposal of such wastewater and fresh concrete aggregates results in high environmental pollution. This study envisages an overview of the current state of knowledge about the reuse of hazardous wastewater and concrete in an environmentally acceptable manner. This study was motivated by the necessity to recycle the wastewater and fresh concrete aggregates resulting from washing out the concrete mixing trucks. Laboratory investigation was conducted and from the test results, it is identified that the performance and properties of concrete is not affected by the reuse of this hazardous wastewater and recycled aggregates.