Current Articles

2021, Volume 39,  Issue 4

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ELECTROLYSIS TREATMENT OF AMMONIUM CHLORIDE WASTEWATER BY DOUBLE CHAMBER MEMBRANE PROCESS
XU Yuan-sheng, SHI Hui-min, NI Jin, DING De-cai, GAO Ming, WANG Li
2021, 39(4): 1-6. doi: 10.13205/j.hjgc.202104001
Abstract:
Aiming at the problem that ammonium chloride wastewater generated from the rare earth and fertilizer industries is difficult to treat, combining with the actual case of a factory in Guangdong province that produced a large amount of ammonium chloride waste solution in the treatment of alkaline copper chloride etching liquid, this paper put forward the method of electrolysis to treat ammonium chloride wastewater and probed into the optimal experimental conditions. It was found that the anion exchange membrane was used to separate the electrolytic cell into a bipolar chamber, which could prevent the contact between chlorine gas and ammonium ion from producing explosive nitrogen trichloride, ensure the safety of operation, and effectively separate chlorine gas from the anode and hydrogen from the cathode, so as to facilitate products collection. On this basis, through exploring the impact of anode chamber and electrolyte concentration, cathode chamber ammonium chloride solution concentration, electrolytic time on treatment effect, optimized experimental condition was as follows:20 mL 5 g/L sodium chloride solution in the anode chamber, 20 mL 100 g/L of ammonium chloride solution in the cathode chamber, constant current of 0.3 A, and electrolysis time of 3 hours, then 93% of chloride ions were transformed into chlorine and sodium hypochlorite. Under this condition, the factory could make an income of at least RMB 1950 by treating 15 t of ammonium chloride waste liquid per day. The membrane electrolysis method could effectively remove chloride ions from ammonium chloride wastewater and produce chlorine gas, sodium hypochlorite and ammonia water. Compared with the traditional electrochemical treatment technology, it had the advantages of simple device and high removal rate, with controllable reaction rate.
THE CAUSE OF FILAMENTOUS ALGAE OUTBREAK IN THE WATER BODIES SUPPLIED BY RECLAIMED WATER: A CASE STUDY ON A SOUTH CHINA RIVER
GAO Shuai-qiang, SHAO Hui-huang, BAI Chun-yin, HU Xing-bao, YU Guang-wei, CHONG Yun-xiao, LI Feng-min, HU Hong-ying
2021, 39(4): 7-12,91. doi: 10.13205/j.hjgc.202104002
Abstract:
Using reclaimed water as the supplementary water for rivers and lakes has become an important measure for urban water environment management. But the inflow of reclaimed water also brings the risk of algal bloom outbreak into the water bodies. In order to explain the phenomenon of filamentous algae's algal blooms easily appearing in the recharged water body of reclaimed water, the growth mode and outbreak causes of filamentous algae in a river recharged with reclaimed water in South China was investigated through field investigation and laboratory experiments. It was found that the growth of filamentous algae had four stages:dormancy, germination, expansion and eruption. In the first three stages, they attached to the bottom of the river and continuously spawned filaments into the water. When the filaments accumulated to a certain amount, they broke free from the bottom and then floated up, and then algal bloom happend. Hydrodictyon(spp) was the dominant species in algal bloom in the rivers. Its growth rate and maximum density were much higher than that of the associated specie, Tolypothrix(spp). So it could be called as algal bloom algae. The optimum growth temperature was about 25℃ for Hydrodictyon(spp), but it still could grow at a low temperature of 15℃ though the growth rate was lower. Therefore, filamentous algal bloom in the river might result from their growth at low temperature, the attachment on the bottom and sufficient light reaching the bottom. The following measures were recommended for the algal bloom control:laying gravel layer on the bottom, tending cold resistant submerged vegetation and aquatic animals fed on filamentous algae, as well as monitoring accumulation of filaments and warning at early stage.
PASSIVATION EFFECT OF CALCIUM PHOSPHATE ON URANIUM IN SEDIMENTS IN DOWNSTREAM WATERS OF A URANIUM MINE
PENG Yan, CHEN Di-yun, CHEN Nan, ZENG Lin-wei
2021, 39(4): 13-19,24. doi: 10.13205/j.hjgc.202104003
Abstract:
Calcium phosphate was used to solidify the simulated uranium contaminated soil, and its passivation effect on the available uranium in the soil was analyzed. Based on this, the sediment in the downstream of a uranium mine in northern Guangdong was collected, and the occurrence forms of uranium before and after the passivation was carried out by sequential chemical extract method. The results showed that the uranium in the sediments mainly occured in Fe-Mn oxides combining species, and the content of available uranium in the sediments could be reduced by adding calcium phosphate. The exchangeable uranium content in stream sediments, pond sediment and paddy soil decreased by 58.27%, 58.04% and 52.62% respectively, and the carbonate bound uranium content decreased by 33.58%, 47.98% and 32.58% respectively. The content of organic combining species increased by 32.95%, 46.86% and 30.50% respectively in stream sediment, pond sediment and paddy soil, and the content of residual uranium increased by 252.67%, 61.90% and 98.96% respectively. The pond sediment and paddy soil with medium risk to the environment before passivation were reduced to low risk, and the proportion of available uranium in the stream sediment with low risk decreased by 1/3. In this study, the effect of calcium phosphate could effectively reduce the harm of uranium in sediment, which provided some reference for radionuclide pollution control and environmental remediation.
APPLICATION OF AAO-MBR PROCESS FOR NON-STOP CAPACITY EXPANSION AND UPGRADING OF A WASTEWATER TREATMENT PLANT
BAI Yu-hua, MA Lin-wei, JIA Tao, ZHANG Fan, ZHOU Yun, TANG Huai-bin, LIU Bai-cang
2021, 39(4): 20-24. doi: 10.13205/j.hjgc.202104004
Abstract:
AAO-MBR process was adopted in a wastewater treatment plant of Chengdu for the capacity expansion and ungrading. The treatment capacity was upgraded from 100000 m3/d to 150000 m3/d by transforming the biochemical treatment unit and advanced treatment unit without adding new land occupation or production stop. Meanwhile, the main indexes of COD, BOD5, ammonia nitrogen and total phosphorus in the effluent quality was upgraded to meet the requirement of class IV standard in Environmental Quality Standards for Surface Water (GB 3838-2002), from the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants (GB 18918-2002) Class I.
NUMERICAL SIMULATION AND ANALYSIS OF FLOW FIELD AND PARTICLE MOTION IN GRID FLOCCULATION TANK
FU Yu, LONG Yun, XIAO Bo, CHENG Huai-yu, LONG Xin-ping
2021, 39(4): 25-29,85. doi: 10.13205/j.hjgc.202104005
Abstract:
Numerical simulation method was used to analyze the characteristics of the internal flow in the front section of the grid flocculation tank. With the vortex velocity gradient and turbulent kinetic energy as the evaluation index of flocculation, the paper verified the rationality of the structural design. In addition, 11 groups of particles with different sizes and effective densities were added to the flow field. Each group randomly released 98560 particles at the entrance of the flow field and their motion was tracked by the DPM model. It was noted that as the particle size increased, the effective density decreased accordingly. The research found that when the particle diameter changed from 1 μm to 1000 μm, the deposition rate was kept less than 10% and the deposition was uniform in each shaft, which could meet the flocculation requirements. When the particle diameter was 1000~5000 μm, the deposition rate increased sharply, but the deposition was uniformed in each shaft. However, when the particle diameter increased to 10000 μm, a large number of particles were deposited in the first shaft, which was not conducive to the uniformity of sludge discharge. So taking deposition rate and the uniformity of sludge discharge into consideration, such large size particles of more than 1000 μm should be avoided in actual engineering practice.
ANALYSIS OF ODOR SOURCES IN STORMWATER PUMP POOL AND STORMWATER PIPE OF A STORMWATER PUMP STATION IN THE SINO-SINGAPORE TIANJIN ECO-CITY
ZHOU Guo-hua, ZHANG Bei, WANG Gang, LI Meng-meng, CHEN Liang
2021, 39(4): 30-35,127. doi: 10.13205/j.hjgc.202104006
Abstract:
The malodorous of the external drainage water from stormwater pumping station has a significant impact on the quality of surface water. In this paper, the Qingtuozi stormwater pumping station in the Sino-Singapore Tianjin Eco-city was selected, and the water sample from stormwater pump pool, the water and sludge samples from stormwater pipe, and the water sample of groundwater were collected to analysis the sources of black and odor from its external drainage water. Results indicated that the main pollution indicators or pollutants in the pump pool, rainwater pipe and groundwater were conductivity, total dissolved solids, total hardness, total alkalinity, chemical oxygen demand, chloride, sulfate, bicarbonate sodium, potassium, calcium and magnesium. The water quality of the stormwater pipe was slightly better than that of the pump pool and groundwater. The main pollutants detected in the sediment of the stormwater pipe were ammonia nitrogen and sulfur. The generation of methane, ammonia, and hydrogen sulfide under the low-oxygen environment in pump pool and stormwater pipe during carbon, nitrogen, and sulfur reduction was the major sources of odor from the external drainage water. Sulfur compounds in water samples of the pump pool and stormwater pipe could change into iron sulfide and manganese sulfide under the disturbance conditions, which was the major sources for the blackening of external drainage water. Sino-Singapore Tianjin Eco-city Qingtuozi Rainwater Pumping Station and stormwater pipe network odor disposal was expected to adopt aeration as the key process, combined with anti-seepage, dredging and other technologies. In addition, initial stormwater and rainfall runoff pollution is the main source of pollutants in the stormwater pumping station and stormwater pipe in Tianjin.
MOLECULAR MECHANISM OF Cr(Ⅵ) REDUCTION INHIBITION BY PANNONIBACTER PHRAGMITETUS BB WITH CO-EXISTING Zn(Ⅱ)
TANG Jia-qi, YANG Wei-chun, YANG Zhi-hui, LIAO Qi
2021, 39(4): 36-41. doi: 10.13205/j.hjgc.202104007
Abstract:
The mechanisms of microbial growth delay and Cr(Ⅵ) reduction inhibition by co-existing Zn(Ⅱ) were revealed through the electron transport system activity, enzyme activity, and real-time quantitative PCR technology. The Cr(Ⅵ) reduction by strain BB was intracellularly and extracellularly inhibited by co-existing Zn(Ⅱ). The decrease of microbial electron transport system activity and cytochrome c oxidase activity caused by co-existing Zn(Ⅱ) were responsible for the extracellular inhibition. While intracellular Cr(Ⅵ) reduction was inhibited by reducing the efficiency of chromium transport. The activities of SOD, CAT, POD, and GST indicated that the co-existing Zn(Ⅱ) was lower toxic to strain BB, which could explained the growth delay of strain BB caused by co-existing Zn(Ⅱ).
RESEARCH ON MANAGEMENT AND CONTROL SYSTEM OF COMBINED SEWER OVERFLOW POLLUTION IN CHINA AND OVERSEAS
HE Jun-chao, LI Ming-ming, LIU Rui, BAI Wei-lan, WANG Qi
2021, 39(4): 42-49. doi: 10.13205/j.hjgc.202104008
Abstract:
The article compared the foreign management and control system of combined sewer overflow (CSO) in the United States, Germany and Japan, and summarized the system of combined sewer overflow pollution control which was formed by the long-term practice of the typical developed countries. Also, it analyzed the CSO bottleneck problems in China by combining the historical context of domestic drainage management and comparative analysis in China and overseas, and then gave suggestion which can help Chinese CSO control be improved in further. Eventually, we preliminary constructed a set of management and control system framework which could provide practical guidance of CSO control of China.
FABRICATION OF CARBON NANOTUBE-DOPED PbO2 COMPOSITE ELECTRODE AND MECHANISM OF CATALYTIC OXIDATION OF BISPHENOL A
WU Meng-yi, LONG Xin, GAO Cong-hao, QIN Xiao, CHEN Yue, TANG Yu-lin
2021, 39(4): 50-56,106. doi: 10.13205/j.hjgc.202104009
Abstract:
CNT-PbO2 composite electrodes with high stability and catalytic activity were obtained by doping carbon nanotubes (CNTs) with different concentrations into PbO2 electrodes by electrochemical deposition. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) analysis proved that CNTs were successfully doped into the PbO2 electrode surface active layer, leading to a decline of PbO2 particle size and an increase of activity surface area. The amount of ·OH radicals generated in the degradation system of bisphenol A (BPA) by CNT-PbO2 electrodes decreased. However, the degradation effect was improved. Cyclic voltammetry (CV) curves and the accelerated life test indicated that the degradation mechanism of BPA was mainly ascribed to the stronger electrochemical direct oxidation ability and higher stability of CNT-PbO2 composite electrodes. Finally, the dominant by-products were obtained, and plausible degradation pathway of BPA was proposed by UPLC & Q-TOF MS test.
ANALYSIS ON THE LAW OF COMBINED DEMERCURATION OF FLUE GAS PURIFICATION UNIT BY ADDING CaCl2
HAN Lei, ZHONG Zhao-ping, JIANG Chao
2021, 39(4): 57-63. doi: 10.13205/j.hjgc.202104010
Abstract:
The combustion of coal releases a large amount of mercury into the atmosphere. In order to explore cost-effective mercury emission control methods, the hydrolysis experiment of CaCl2 crystal was carried out in a tubular furnace. Under certain temperature and atmosphere, CaCl2 could hydrolyze to produce HCl, which was conducive to the oxidation of Hg0 in flue gas. The results showed that the hydrolysis rate increased with the increase of reaction temperature. The experiment of CaCl2 solution evaporation combined with mercury removal was carried out in a fluidized bed furnace. Spraying CaCl2 solution in coal could significantly improve the oxidation rate of SCR denitrification device to Hg0; compared with spraying in raw coal, spraying CaCl2 solution in the evaporation drying tower before FF would significantly improve the effect of removing Hg by FF bag filter; spraying CaCl2 solution into coal would increase the concentration and proportion of Hg2+ in flue gas, and the removal effect of WFGD wet desulfurization unit on gaseous Hg was improved. On the whole, the higher the temperature was and the higher the chlorine addition ratio was, the higher the synergistic mercury removal efficiency of the flue gas purification device was.
MODEL ANALYSIS FOR EMISSIONS OF LIGHT-DUTY GASOLINE VEHICLES IN A TYPICAL CITY
YIN Zi-yuan, ZHANG Kai-shan
2021, 39(4): 64-71. doi: 10.13205/j.hjgc.202104011
Abstract:
The objective of this work was to develop driving modes for a typical city in China and quantify its corresponding emissions. Using Chengdu as an example, twenty-six light-duty gasoline vehicles in compliance with the Phase V national emission standards (GB 18352.5-2013) were selected in this study. A portable emission measurement system (PEMS) was used for driving cycle and real-world emission measurements. The classification and regression tree (CART) was used to develop driving modes for emission modeling. Five driving modes, including acceleration, deceleration, cruise, idle, and stop and go (SNG) were defined and demonstrated to be able to characterize the real-world emissions and fuel consumption. In general, emissions and fuel consumption differ by driving modes with acceleration being the highest, followed by cruise, SNG, deceleration and idling. Depending on pollutant, the ratio of emissions between two different driving modes could be as high as a factor of 12. Furthermore, vehicle emissions from a majority of selected vehicles in this study exceeded its compliance emission standards and were episodic. This indicated that the developed driving modes could be used to characterize vehicle emissions at a high temporal resolution, and develop emission inventory for traffic management and emission control.
SEASONAL DIFFERENCE ANALYSIS OF THE RELATIONSHIP BETWEEN PM2.5 AND LAND USE: A CASE STUDY OF WEIFANG
ZHANG Kuo, ZHANG Yong-bin, LI Cheng-ming, DAI Zhao-xin
2021, 39(4): 72-78. doi: 10.13205/j.hjgc.202104012
Abstract:
With the acceleration of industrialization and urbanization, China's frequent occurrence of haze weather has seriously affected People's daily life and health. As an important part of haze, PM2.5 has become a hot issue. The type of land use can significantly affect the pollution concentration of PM2.5, and the study of the relationship between the type of land use and PM2.5 pollution is of great significance for air pollution control. At present, most of the existing researches are based on regression model to analyze the fixed influence of land use type on PM2.5 on an annual scale. However, the relationship between land use type and PM2.5 is complex, and the influence intensity is not the same in different seasons. Based on this, the contribution rate of land use type to PM2.5 concentration in different seasons was quantitatively discussed by using the method of boosted regression tree. The results showed that the land use type had significant difference in the influence of PM2.5 concentration in different seasons, and the dominant factors in spring, summer, autumn and winter were branch road (27.37%), secondary trunk road (19.17%), vegetation coverage (37.23%) and construction land (86.37%). In addition, according to the influence curve of different land use types on PM2.5 in different seasons, specific and quantitative planning indicators of optimizing the layout of greening construction and strengthening traffic control were provided for the control of PM2.5 pollution in Weifang.
AEROSOL DIFFUSION CHARACTERISTICS IN CLOSED AND VENTILATED SPACES
YIN Yue, LI Yong-xi, FU Hao, LUAN Yi-gang
2021, 39(4): 79-85. doi: 10.13205/j.hjgc.202104013
Abstract:
Since aerosols have the characteristics of spreading viruses, the aerosol diffusion characteristics of indoor closed and ventilated spaces have important research significance. The proportional modeling of closed spaces and human body models were established, and numerical simulation calculations were carried to obtain the transient propagation path and range of aerosol particles. In this paper, Realizable k-ε turbulence model and DPM (discrete phase model) were used to carry out two-phase transient calculations. The results showed that under exhalation conditions such as sneezing and coughing, large-diameter particles would sink, and small-diameter particles would spread to the human head area at 2 m away with the airflow. Due to the temperature of the human body was higher than the temperature of the surrounding environment, the thermal plume would appear near the body, and the aerosol particles would flow upward with it and move downward with the circulation at the top. Through the simulation study of steady ventilation schemes, it was found that in the three ventilation schemes on the front side, left side, and right side (relative to door), two vortices appeared under the body model for both left and right ventilation. The vortex occupying the central area would cause the particles to stay here. In the front ventilation scheme, 64.8% of the particles flowed out with the air flow, followed by the left scheme, 59.3%, and the right ventilation scheme had a poorer outflow effect, accounting for 46.9%. Therefore, among the three schemes, the front side ventilation scheme had a better effect. It could provide reference for the selection of indoor ventilation mode and the reduction of indoor breathing aerosol particles when people were indoors.
THE SOURCE, MIGRATION, TRANSFORMATION AND EFFECT OF CHLORINE IN BLAST FURNACE PRODUCTION
CHENG Zheng-lin, ZHU Xiao-hua, LI Peng-fei
2021, 39(4): 86-91. doi: 10.13205/j.hjgc.202104014
Abstract:
The elemental chlorine in the incoming raw materials undergoes a series of migration and transformation in the blast furnace, mainly enters into the blast furnace gas in the form of hydrogen chloride (HCl), which will lead to system corrosion, subsequent blast furnace gas desulfurization catalyst poisoning and cause environmental impacts. This paper provided an overview of the sources and behaviors of chlorine in blast furnace and its occurrence state in each furnace charge, analyzed the contributions of chlorine's main income items and expenditure items based on the study of the blast furnace chlorine balance, and introduced the migration and transformation behavior of organic and inorganic chlorine in the blast furnace. Although chlorine in the blast furnace production process has positive effect of improving the low temperature reduction degradation of sinter and improving the permeability of the melting zone, it also has a lot of adverse effects on the operation of the blast furnace and the environment. The above contents provided theoretical basis for controlling the negative effects of chlorine on blast furnace production, and the specific dechlorination measures of blast furnace were further summarized, while controlling the chlorine content of raw material from the source was the most direct, effective and economical measure.
THE AEROBIC DEGRADATION OF NUTRITIONAL COMPLEXED KITCHEN WASTE BY MIXED MICROBIAL FLORA
ZHAO Zi-xuan, QIU Wei-hua, WANG Pan
2021, 39(4): 92-99. doi: 10.13205/j.hjgc.202104015
Abstract:
The diversity analysis and identification of a newly isolated kitchen-waste (KW) degrading microbial flora CCJ-Bac-1 were carried out. CCJ-Bac-1 was dominated by Bacillus spp., including B. velezensis, B. badius, B. thermopylovorans, Paenibacillus pueri, Lactobacillus gasseri, Komagataeibacter saccharivorans. Among CCJ-Bac-1, B. velezensis, B. badius and B. thermopylovorans were firstly reported in the degradation of kitchen-waste. Then, the physical and chemical properties of the kitchen waste were regulated with peanut shells (PS) and banana peels (BP). The determined optimal ration of kitchen-waste to peanut shells and banana peels was 0.7:0.2:0.1. Finally, the complex kitchen waste was degraded by mixed microbial flora that containing equal ration (by volume) of CCJ-Bac-1, Thermophilic hyphomycete and Streptococcus thermophilus, resulting in the highest weight loss rate of 63.9%. This study was conducive for converting kitchen-waste to the raw materials for consequently biological transformation.
EFFECTS OF PRETREATMENTS AND SUBSTRATE COMPOSITIONS ON ANAEROBIC DIGESTION OF ORGANIC WASTE
XU Yi-wen, YANG Guo-dong, WANG Feng-xia, CHEN Hui-ting, HUANG Ai-lian, LIU Li-ting, JIANG Yan-hang, SONG Ying-chun, JIANG Jian-guo
2021, 39(4): 100-106. doi: 10.13205/j.hjgc.202104016
Abstract:
With the implementation of waste sorting policy in China, efficient utilization of organic waste becomes a great challenge in China. In this paper, continuous experiments on anaerobic digestions of kitchen waste, fruit and vegetable waste and garden waste were conducted, while ultrasound and alkali-thermal pretreatment were applied to enhance methane production, with the mono-digestion of food waste served as the control. According to different OLRs, the reaction period was divided into low OLR phase[OLR=1, 2 g/(L·d)] and high OLR phase[OLR=4, 6 g/(L·d)]. The results showed that under low OLR, all reaction systems showed strong stability, among which, kitchen waste had the highest VS removal rate of 90.3% and methane yield of 460 mL/g. Besides, after ultrasonic pretreatment and alkali-thermal pretreatment, the methane yields of co-substrates were increased by 7%~8% and 3%~7%, respectively. Under high organic load, the stability of mono-digestion system was significantly reduced, specifically, the pH value was decreased to 6.70 and the concentration of VFA and TAN was accumulated to 1230, 1519 mg/L, while the VS removal rate and methane yield were reduced by 2.8% and 11% as well. However, the co-digestion systems showed stronger resistance to high OLRs. Compared with kitchen waste, the methane yield of co-substrate was increased to 420 mL/g. After ultrasonic pretreatment, the methane yield was further increased by 3%, while the methane yield after alkali-thermal pretreatment was decreased by 4%.
PROGRESS IN PREPARATION OF CARBON NANOTUBES BY THERMAL CATALYSIS OF WASTE PLASTICS
FENG Shi-yu, LI Yang, LI Kai, HU Bin, LIU Ji, LU Qiang
2021, 39(4): 107-114. doi: 10.13205/j.hjgc.202104017
Abstract:
Carbon nanotubes (CNTs) have excellent physical and chemical properties, and wide application prospects in many fields. However, the high cost of raw materials limits its large-scale production and application. Waste plastics has huge annual yield, rich in carbon and hydrogen. They can produce a large number of gaseous carbon sources for the growth of CNTs during catalytic pyrolysis, so waste plastics has a great potential in the preparation of CNTs. Using waste plastics as raw material to synthesize CNTs can not only reduce the production cost of CNTs, but also realize the efficient disposal and high value utilization of waste plastics. Based on the relevant literatures in the field of synthesis of CNTs from waste plastics in recent years, the review introduced the growth mechanism of CNTs, and summarized the effects of plastic-type, catalyst and reaction conditions on the yield and quality of CNTs. Finally, the prospect of preparation of CNTs from waste plastics by thermal catalysis was indicated, which provided a theoretical basis for resource utilization of waste plastics.
RESEARCH PROGRESS ON RECOVERY OF CATHODE MATERIAL FROM SPENT LITHIUM-ION BATTERIES BY PYROMETALLURGY
LI Zhi-qin, ZHUANG Xu-ning, SONG Xiao-long, LI Fei, LI Ying-shun, GU Wei-hua, BAI Jian-feng
2021, 39(4): 115-122,146. doi: 10.13205/j.hjgc.202104018
Abstract:
Due to the existence of valuable and hazardous materials, it is of great practical significance to carry out the recovery and regeneration of spent lithium-ion batteries with environment-friendly ways. With the characteristics of short treatment process, high efficiency and easy industrial application, pyrometallurgy has become the hotspot of spent lithium-ion batteries recycling. It can realize the recycling of valuable metals such as Li, Co and Ni based on the chemical transformation at high temperatures. This paper summarized the application of pyrometallurgy in the cathode material from spent lithium-ion batteries and its research status, including electrode materials dissociation, valuable metals recycling, the positive active material regeneration, etc,. Meanwhile, the advantages and disadvantages of different thermal treatment technology were analyzed and the research direction of the cathode material by pyrometallurgy in the future was also prospected.
PILOT STUDY ON TREATMENT OF ACARBOSE RESIDUE BY A MULTI-STAGE ANAEROBIC SYSTEM
YANG Tao, LIU Peng-yu, XU Ya-qiang, CHEN Dai-jie, JING Mei-ying, CHU Xiao-he
2021, 39(4): 123-127. doi: 10.13205/j.hjgc.202104019
Abstract:
Acarbose produced a large amount of fermentation waste in the production process. At present, the incineration method is generally expensive, therefore an environmentally friendly and inexpensive treatment method is urgently needed for this treatment. In this paper, the acarbose slag was treated by a multi-stage anaerobic system. When the feed load reached 4.173 kg (by dry residue)/(m3·d), the average total gas production of multistage anaerobic system was 390.4 m3/d. The average soluble COD of the effluent was 8946 mg/L, the system could completely degrade the residual mycelium in the waste residue, the solid mass removal rate of the waste residue was 52.9%, the residual acarbose in the waste residue decreased from 0.361 mg/g (dry residue) to 0.027 mg/g (dry residue), and the drug residue removal rate was 92.5%. The humification degree of anaerobic effluent was greatly improved, and the reduction and harmless treatment of acarbose residue were realized.
REVIEW ON PREDICTIVE MODELS FOR MUNICIPAL SOLID WASTE PRODUCTION
WU Fan, NIU Dong-jie
2021, 39(4): 128-133. doi: 10.13205/j.hjgc.202104020
Abstract:
Prediction of generation rate of MSW is of great significance to its planning and subsequent disposal. Models in previous research were summarized into two categories:regression analysis models for large-scale prediction and time series models for small-scale but precise prediction. And each sub-category was compared in detail. The influencing factors of MSW were divided into three categories:regional overall factors, residents' living factors and other factors, and their selection was discussed separately. Finally, suggestions on three major steps, determination of land scale, lag of time and input parameters were given, and the existing problems in predictive models for municipal solid waste were also summarized.
STRATEGY OF INFORMATION STORAGE AND TRANSPORTATION OF MEDICAL WASTE IN EPIDEMIC SITUATION
WANG Yan, ZHANG Jun-lin, ZHOU Li
2021, 39(4): 134-139. doi: 10.13205/j.hjgc.202104021
Abstract:
When the epidemic COVID-19 broke out, the effective treatment of medical waste became an important support and guarantee segment of epidemic prevention. The article first analyzed the nature and characteristics of the medical waste, collected relevant statistical data of the epidemic area, and obtained the characteristics of medical waste storage and transportation during the epidemic. Then combined with the Internet of things and big data related information technology, an intelligent management and control platform for medical waste was constructed, and the emergency command system of medical waste storage and transportation in the epidemic situation was designed in detail. At the same time, a mathematical model for the construction of medical waste storage and transportation under the epidemic situation was proposed, and the idea of optimizing it with the optimization algorithm was proposed, so as to obtain a medical waste storage and transportation strategy that adapted to the emergency situation of the epidemic, which could provide theoretical support for public health safety protection decisions.
INFLUENCE MECHANISM AND KINETIC STUDY OF CaO PRETREATMENT ON HIGH-SOLID SLUDGE ANAEROBIC DIGESTION PERFORMANCE
ZHANG Bo, ZHAO Yi-hua, TAO Jun, JI Min, MA Tong-yu, SHANG Chen
2021, 39(4): 140-146. doi: 10.13205/j.hjgc.202104022
Abstract:
To resolve the problem of low hydrolysis rate of high-solid waste activated sludge during anaerobic digestion process, CaO was used to disintegrate high-solid sludge. Physical and chemical characters of sludge before and after alkaline pretreatment were evaluated in terms of particle size, and soluble COD, protein, carbohydrate. Effect of alkaline pretreatment on cumulative methane yield and organism decomposition during high-solid anaerobic digestion process were also studied. The influence mechanism of EPS, cell wall and cell membrane cracking degree on anaerobic digestion performance under different alkali levels were studied. The results indicated that after the CaO pretreatment, the particle size of sludge was hardly changed, and the concentrations of SCOD, soluble protein and carbohydrate showed an obvious increase trend. The disintegration degree increased with the dosage of CaO. After alkaline pretreatment, the cumulative methane yield increased by 22.9%~34.8%. The mechanism discussion results showed that only organic matters in EPS could be released during low-alkali pretreatment, which promoted the cumulative methane yield, while organic matters in EPS and intracellular polymers were both released during high-alkali pretreatment, which led to the increase of cumulative methane yield. Kinetics study results showed that alkaline pretreatment could not only enhance methane yield, but also accelerate the anaerobic digestion and shorten the inhibitory stage.
EFFECT OF FREEZING/THAWING PRETREATMENT ON EXCESS SLUDGE DISINTEGRATION AND TREATMENT EFFICIENCY OF MICROBIAL ELECTROLYSIS CELL
SUN Xing, HU Kai, LEI Chen-yu, CHEN Wei
2021, 39(4): 147-155. doi: 10.13205/j.hjgc.202104023
Abstract:
In this study, freezing/thawing pretreatment was adopted to disrupt sludge matrix in order to improve hydrolysis rate and degradation of organic matter in microbial electrolysis cell (MEC) feeding with excess sludge. The influence of freezing/thawing on sludge characteristics and performance of subsequent MEC was discussed. The results showed that freezing/thawing pretreatment could effectively promote the floc disintegration, cell rupture and organics dissolution of the sludge. When being freezed at -18℃ for 72 h and then thawed at 26℃ for 3 h, the SCOD content in the sludge increased by 2.58 times. At applied voltage of 0.7 V, with freezing/thawing-pretreated sludge as the substrate, the removal rates of SS and TCOD in MEC exceeded 40% and 60%, respectively. Compared with raw sludge, the pretreatment increased coulomb efficiency and cathode hydrogen recovery in MEC by 5.8% and 6.7%, respectively. Microbial community analysis showed that freezing/thawing pretreatment facilitated the enrichment of exoelectrogens (including Proteobacteria and Firmicutes) in MEC, therefore improved the overall utilization and energy recovery from excess sludge via MEC.
ENVIRONMENTAL IMPACT OF LANDFILL ON GROUNDWATER QUALITY BASED ON INDEX ANALYSIS AND GIS METHOD
JIA Chao, YANG Xiao, LIU Sen, WANG Song-tao, WANG Hui-hui, LIU Jian-zhang
2021, 39(4): 156-163,155. doi: 10.13205/j.hjgc.202104024
Abstract:
To reasonably evaluate the pollution potential of the landfill site and its impact on the surrounding groundwater environment, a landfill site in Shandong Province was selected as the research object. LPI index method and WQI index method were used to evaluate the pollution situation of landfill leachate and the water quality of surrounding groundwater. At the same time, GIS spatial analysis and other functions were used to evaluate the pollution impact distribution. Using numerical simulation and ammonia nitrogen as the characteristic pollutant, the laws of pollutant migration and diffusion in leachate were calculated and analyzed. The results showed that the leachate in the study area had a large pollution potential and risk of polluting the surrounding groundwater. At present, the quality of surrounding groundwater met the requirements of WHO and China national standards, and was generally in good condition. However, with the leakage of leachate, the polluted area of ammonia nitrogen and other pollutants gradually spread into the feather shape, and the groundwater quality would continue to deteriorate. It was expected that the leachate would begin to contaminate the groundwater in the surrounding residential area and gradually expand by 2025. So it is necessary to take corresponding anti-seepage measures to protect the surrounding groundwater.
RESEARCH PROGRESS OF TECHNICAL OPTIMIZATION OF SEWAGE SLUDGE COMPOSTING
CHE Yue-chi, YAN Bei-bei, WANG Xu-tong, CHEN Guan-yi, DAN Zeng, MENG De-an
2021, 39(4): 164-173. doi: 10.13205/j.hjgc.202104025
Abstract:
As sewage sludge production in China is increasing year by year, sewage sludge disposal is facing with severe challenges. Sewage sludge composting technology is a potential SS disposal method that in line with the concept of sustainable development. High efficiency, high value and intelligence are the developing direction for SS disposal. In this paper, the development status and the main challenge of sewage sludge composting was summarized from the aspects of the optimization of composting conditioner, aeration strategy, deodorization process and the composting equipments. The result showed that the composting conditioner ought to be developed, taking waste utilization, recyclable equipment and biological utilization into consideration. The composting equipment needed to be improved with the combination of sensor feedback and software numerical simulation. Moreover, the introduction of new aeration and deodorization process were needed to develop efficient composting equipment. This study provided valuable suggestions for the further promotion and development of sludge composting technology in China.
PASSIVATION AND REMEDIATION OF MERCURY CONTAMINATED SOIL BY POLYMER AND PASSIVATOR
YU Gao, CHEN Fen, ZHAO Cheng-gang, HOU Jian-wei, DENG Xiao-mei
2021, 39(4): 174-179,186. doi: 10.13205/j.hjgc.202104026
Abstract:
A pot experiment was carried out to study the effects of adding high polymer with strong acid resistance and traditional organic or inorganic passivator to passivate the heavy metal mercury in soil, and to explore its effect on the physical and chemical properties of soil, the growth of plants, the form of mercury in soil and the activity of enzyme. The results showed that:compared with CK, adding different passivators could effectively improve the physical and chemical conditions of mercury contaminated soil and soil microenvironment, and promote plant growth. Compared with CK, the proportion of available mercury in soil was significantly reduced by different passivators, and the ratio of water-soluble and exchangeable mercury in soil decreased by 106%~315% and 12.61%~34.60%, respectively. Compared with single passivator, the bonding passivator with polymer could effectively adsorb and fix mercury, and reduce the bioavailability of heavy metal mercury in soil. The biochar polyacrylamide (BI-PAM)treatment had the best effect on soil organic matter content and pH, and the best passivation effect on heavy metal mercury in soil(water soluble mercury, exchangeable mercury and Fe-Mn oxide bound mercury accounted for the smallest proportion of total mercury, which were 1.05%, 12.14% and 12.72% respectively, while strong organic bound mercury and residual mercury accounted for the highest proportion, which were 15.86% and 58.23% respectively), which could promote the yield and reduce the absorption and enrichment of mercury in cabbage leaves. According to the experimental results, the bonding passivator of biochar and polyacrylamide was recommended in application in acid soil polluted by mercury.
APPLICATION OF MONITORING TECHNOLOGY FOR CONTAMINATED GROUNDWATER IN AN INFORMAL LANDFILL SITE
LU Guang-hua, LIU Chang-bo, XIA Chun, YUE Chang-sheng, LIU Shi-cheng, WU Jie
2021, 39(4): 180-186. doi: 10.13205/j.hjgc.202104027
Abstract:
In this paper, a new method was proposed to guide the design and application of groundwater monitoring scheme based on the distribution characteristics of waste. Combined with the new technology of single well and multi-layer monitoring wells, the groundwater samples of different depths were collected and tested efficiently. Through the combination of aerial remote sensing detection technology and numerical simulation calculation of site geological prospecting data, the total amount and distribution characteristics of garbage were effectively analyzed, and the composition and distribution characteristics of main groundwater pollution source (humus garbage) were determined. Further, combined with the hydrogeological conditions of the site, the groundwater monitoring scheme was designed, and a new type of single well with three layers was constructed, the 18 groundwater samples of different depths (6 m, 12 m and 18 m) at each groundwater monitoring well were collected and analyzed efficiently. This paper provided design and application experience of groundwater monitoring technology in landfill site, and useful references for the development of groundwater monitoring technology.
ANALYSIS OF DISTRIBUTION CHARACTERISTICS OF BTEX IN A DYESTUFF CHEMICAL SITE
PENG Jin-jin, LI Lin, ZHENG Chuan, HU Ling, WU Xiao-xu
2021, 39(4): 187-194. doi: 10.13205/j.hjgc.202104028
Abstract:
In order to understand the distribution characteristics of benzene series(BTEX) in the soil of a dye chemical pollution site in the middle reaches of the Yangtze River, 17 groundwater samples and 343 soil samples were determined. The results showed that:the distribution of BTEX in groundwater and soil was consistent, and the pollution had homology; due to the flat terrain and poor horizontal permeability of soil, the diffusion range of pollutants was limited. Influenced by soil anti-pollution performance, benzene, m,p-xylene and o-xylene were mainly detected in soil layer above 7.2 m, the three substances mainly existed as light non-aqueous phase liquid (LNAPL) in the soil, and they accumulated near the groundwater level, and continued to migrate in the saturated zone in dissolved state. Chlorobenzene mainly existed in soil as heavy nonaqueous liquid (DNAPL), the concentration of chlorobenzene in soil was higher, and the depth of migration was deeper, related to the form, migration time and geological conditions. It was suggested that the combination of ex-situ normal temperature desorption and chemical oxidation technology should be used for shallow contaminated soil, and in-situ chemical oxidation technology should be used for deep contaminated soil and polluted groundwater, in the remediation project.
RESEARCH PROGRESS ON IRON ACTIVATED PERSULFATE IN SITU REMEDIATION OF ORGANIC CONTAMINATED SOIL
HOU Si-ying, DENG Yi-rong, LU Hai-jian, LV Ming-chao, SU Jia-yun, LI Qu-sheng
2021, 39(4): 195-200,194. doi: 10.13205/j.hjgc.202104029
Abstract:
In-situ chemical oxidation remediation technology is a commonly used method to treat site contaminants. Persulfate(S2O82-), as a new remediation agent in situ chemical oxidation technology, is more stable, easier to be transfered and has a wide range of pH applications. S2O82- can be activated and decomposed to SO4-· under light, heat, transition metal and other conditions. In this paper, the effects of different activation modes on the oxidative degradation of organic pollutants by persulfate were introduced in the analysis of persulfate oxidation mechanism, and the research status of persulfate activation by different iron activation modes in organic-contaminated soil was emphatically introduced. At the same time, the existing problems and the development trend were prospected.
EXPERIMENTAL STUDY ON RESTORATION EFFECT OF IN SITU THERMAL DESORPTION IN COKING CONTAMINATED SITES
ZHAO Tao, ZHOU Yu, MA Gang-ping, LI Shi-qing, CAO Xue-long
2021, 39(4): 201-205. doi: 10.13205/j.hjgc.202104030
Abstract:
In-situ gas thermal desorption experiments were conducted on coking sites contaminated by benzene and PAHs. In this paper, the disposal effect and energy consumption of the secondary combustion of organic pollutants reached an optimal state by innovatively combining combustion and extraction and means of the design form with small extraction tube. In the modular design of tail gas and tail water, the combined process of secondary combustion and adsorption of activated carbon, as well as oil-water separation and activated carbon was adopted, thereby enhancing the removal effect of organic pollutants, and reducing the production of waste gas and activated carbon. Through the remediation experiments conducted on a coking contaminated site of 100 square meters, the four heating periods in the thermal desorption process were well-defined, and the remediation duration was about 55 days. After remediation, the concentrations of benzo (a) pyrene and benzene were less than the standard values for screening the second type land according to Soil Environment Quality Risk Control Standard for Soil Contamination of Development Land (GB 36600-2018), and the exhaust emissions conformed to the Comprehensive Emission Standard of Air Pollutants of Beijing (DB 11/501-2017).