A facile synthesis of Co-doped g-C

Co-g-C3N4 catalyst was prepared by a simple calcination method using melamine and Co(NO3)3·6H2O as precursors. X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR) were used to characterize the prepared samples. The results indicated the Co species are successfully coordinated with g-C3N4. Degradation experiments showed that Rhodamine B can be degraded effectively at a very low cobalt doping concentration (0.2 wt %). The enhanced catalytic activity may result from the synergistic effect of visible light photocatalysis and sulfate radical based Co-g-C3N4/PMS system

Quantitative Assessment of Soil Physical Quality in Northern China Based on S-theory

ABSTRACT Quantitative assessment of soil physical quality is of great importance for eco-environmental pollution and soil quality studies. In this paper, based on the S-theory, data from 16 collection sites in the Haihe River Basin in northern China were used, and the effects of soil particle size distribution and bulk density on three important indices of theS-theory were investigated on a regional scale. The relationships between unsaturated hydraulic conductivityKi at the inflection point and S values (S/hi) were also studied using two different types of fitting equations. The results showed that the polynomial equation was better than the linear equation for describing the relationships between -log Ki and -logS, and -log Kiand -log (S/hi)2; and clay content was the most important factor affecting the soil physical quality index (S). The variation in the S index according to soil clay content was able to be fitted using a double-linear-line approach, with decrease in the S index being much faster for clay content less than 20 %. In contrast, the bulk density index was found to be less important than clay content. The average S index was 0.077, indicating that soil physical quality in the Haihe River Basin was good

Pollution and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Urban Rivers in a Northeastern Chinese City: Implications for Continuous Rainfall Events

Most studies have concentrated on the distribution of polycyclic aromatic hydrocarbons (PAHs) in air, water, and soil; however, little is known about their behavior during urban wet deposition. During frequent urban rainstorms, surface runoff carries large amounts of organic pollutants into water, which has a significant impact on the quality of the water environment. “Poseidon” made landfall in Jilin Province on 27 August, 3 September, and 7 September 2020, respectively, causing some impact on the surface water. Gas chromatography–mass spectrometry (GC–MS) was used to measure the concentrations of 16 major PAHs in stormwater and water samples from the Yitong River. The PAH concentrations in rainwater runoff gradually decreased with increasing rainfall duration. The PAHs in the Yitong River water samples were mainly composed of two to three rings, with total concentrations ranging 279.19–756.37 ng/L. Ratio characterization and principal component analysis of the sources of PAHs in the water samples revealed that some water bodies had also been contaminated by oil spills in addition to combustion emissions from coal and motor vehicle oil. Health and environmental risks were assessed for PAHs in water bodies from the Yitong River, and health risk assessment showed that exposure to PAHs in the water is not a health risk for human beings; however, the risk for children is higher than that for adults and requires attention. Although the environmental risk is moderate, the risk from Benzo(a)anthracene(BaA) alone is high and requires ongoing attention. In terms of the sustainability of drinking water sources, consideration should be given to taking necessary regulatory and protective measures to prevent further contamination. These results serve as a guide for managing PAHs in urban water bodies and managing water pollution

The Correlation Analysis of TOC and CODCr in Urban Sewage Treatment

Total organic carbon (TOC) and chemical oxygen demand (CODCr) are indicators of the degree of organic pollution in water. At present, CODCr is mainly used as an evaluation index in China, and the detection method of CODCr is more complicated and time-consuming than TOC. In this paper, it uses the Micro-Pressure Inner-Loop Bioreactor (MPR) to treat urban sewage, studies the treatment effect of MPR on organic pollutants, and further analyzes the correlation between TOC and CODCr. TOC and CODCr of municipal wastewater and MPR treated effluent were measured by total organic carbon analyzer and dichromate method respectively, and the degree of organic pollution of water samples was analyzed. The results showed that the average removal rates of TOC and CODCr in municipal wastewater were 83.54% and 90.81%, respectively. The theoretical correlation coefficient between TOC and CODCr in experimental raw water was only 0.7322. After MPR treatment, the correlation coefficient increased to 0.9534. For water samples with fixed contaminants and stable contents, TOC can be used to calculate water CODCr by linear fitting relationship

The correlation analysis of TOC, COD

Water samples from different biochemical reaction time in one reactor period in Micro-Pressure Inner-Loop Bioreactor (MPR) were measured respectively with adopt Excitation-emission matrix (EEM) fluorescence spectroscopy, Total organic carbon (TOC) and chemical oxygen demand (CODCr),analyzed the correlation among the fluorescence integrates volume, TOC and CODCr.Results showed that with the increase of biochemical treatment time, sewage fluorescence integrates volume declined significantly, known fluorescence integrates volume, CODCr and TOC value better correlation, by fluorescence spectrometry analyzed fluorescence characteristics of sewage to determine the organic wastewater degradation effect, can be simpler and more rapid the judgment of the sewage treatment effect

Study on Aeration Optimization and Sewage Treatment Efficiency of a Novel Micro-Pressure Swirl Reactor (MPSR)

This study developed a new type of micro-pressure swirl reactor (MPSR) for treating rural domestic sewage with variable water volume in northern China. The transformation of a traditional aeration tank to MPSR was mainly divided into three steps. Firstly, the aeration device was installed on one side of the aeration tank. Secondly, most of the top cover plate was sealed. Finally, the liquid level-lifting zone was set to achieve micro-pressure. The study measured the flow velocity and dissolved oxygen (DO) distribution in the main reaction zone of MPSR, studied the effects of MPSR sewage treatment in continuous operation mode and sequential batch operation mode, and analyzed the main microbial species. The experimental results showed that a stable circular circle flow and a spatial DO gradient in MPSR were formed when the aeration rate of MPSR was 0.2 m3/h. Through the MPSR sewage treatment experiment in two operation modes, it could meet the current requirements of rural environmental pollution controlled in China. Analysis of the types of microorganisms showed that microorganisms with different functions gathered in different zones of the MPSR due to the different dissolved oxygen environment and water flow environment, which further improved the ability of MPSR to simultaneously remove nitrogen and phosphorus

Study on the Influence of Different Carbon Sources on Nitrogen and Phosphorus Removal with Micro-pressure swirl Reactor

To explore the suitable external carbon sources for Micro-pressure swirl Reactor (MPR), the experiment was run in parallel through two MPRs, using starch and glucose as carbon sources respectively. Research indicated that under the experimental operating conditions, using starch as the carbon source could more effectively promote the biological denitrification of the MPR system. Due to the structural characteristics of MPR and the slow degradation of starch, the demand for carbon source for denitrification was ensured during the operation cycle, so that the system obtained a better denitrification effect. The test results provided reference for the selection of the external carbon source of the MPR process

Analysis of the Electricity Consumption in Municipal Wastewater Treatment Plants in Northeast China in Terms of Wastewater Characteristics

A municipal wastewater treatment plant plays an important role in treating urban sewage and reducing the quantity of pollutants discharged into rivers. However, the energy consumption of the municipal wastewater treatment industry is large. High energy consumption indirectly produces ecological damage, accelerates the energy crisis, and increases carbon emissions. For energy conservation and emission reduction in wastewater treatment plants, it is first necessary to identify the main factors influencing energy consumption. Electricity consumption accounts for more than 80% of the energy consumption of wastewater treatment plants. Wastewater quantity and wastewater quality have become the key influencing factors of energy conservation and consumption reduction in wastewater treatment plants. In this study, a municipal wastewater treatment plant in Northeast China was selected as the research object, and the measured data, such as air temperature, wastewater quantity, wastewater quality, and electricity consumption of the plant from 2017 to 2020 were statistically analyzed to explore the influences of temperature and wastewater quantity and wastewater quality indicators of influent and effluent on energy consumption. Firstly, the range of influent quantity in the wastewater treatment plant was large. The influent quantity in summer was high because some rainwater entered the sewage treatment plant. In winter, average daily electricity consumption (ADEC) was higher than that in summer. The relationship between ADEC and the wastewater quantity showed a positive correlation, and ADEC slowly increased with the increase in wastewater quantity. Electricity consumption per unit of wastewater (UEC) was negatively correlated with the wastewater quantity, but the correction coefficient in winter was larger than that in summer. Secondly, the ranges of chemical oxygen demand (CODCr) and ammonia nitrogen in influent were large, and the ranges of CODCr and ammonia nitrogen in effluent were small. Influent CODCr concentration was negatively correlated with influent ammonia nitrogen concentration. ADEC increased slightly with the increase in influent CODCr concentration. In winter, the increasing trend of ADEC with the influent CODCr concentration was higher than that in the summer. The increasing trend of UEC with the increase in influent COD concentration in summer was more significant than that in winter. Thirdly, influent CODCr in 11.6% of the samples exceeded the corresponding designed value, and influent ammonia nitrogen concentration in 41.4% of the samples exceeded the corresponding designed value. Effluent CODCr in 10.6% of the samples exceeded the First Level Class B standard in “Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants (GB18918-2002)”, and unqualified CODCr in 94% of the effluent samples was ascribed to the unqualified ammonia nitrogen concentration in the influent samples. The electricity consumption level under abnormal conditions was higher than that under normal conditions. Fourthly, ADEC was positively correlated with the average daily CODCr reduction. The correction coefficient of ADEC with average daily CODCr reduction was greater in winter than that in summer. Fifthly, the average electricity consumption per unit of wastewater was close to the national average energy consumption, displaying the characteristics of high energy consumption in winter and low energy consumption in summer. The correlation analysis results of unit electricity consumption and temperature showed that when it was below 0 °C, the lower the temperature, the higher the electricity consumption. In Northeast China, the influences of seasons and temperatures on the electricity consumption of sewage plants were obvious. Accordingly, it is necessary to implement the diversion of rainwater and sewage, reduce the discharge of unqualified wastewater from enterprises, and take thermal insulation measures in winter. In addition, activated sludge microorganisms suitable for a low temperature area and the optimal scheduling of sewage pipe networks can also improve the operation and management of sewage treatment plants

Effect of controlling filamentous bulking sludge by Sequencing Batch Reactor Activated Sludge Process

Three groups of SBR reactors A, B and C with different aeration time were set up to culture the activated sludge which has already bulked. The results showed that the settling performance of activated sludge in reactor A changed a little, but reactors B and C had been significantly improved. High-throughput sequencing results showed that the aeration time had a significant inhibitory effect on the growth of Thothrix, and the longer the aeration time was, the more obvious the inhibition was. When the aeration time is more than 6h, the SBR mode can effectively inhibit filamentous sludge bulking, and the longer the aeration time, the better the effect