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Presently, the improvement of soil organic matter is the basis to ensure food security, but the accumulation and transformation characteristics of soil phosphorus (P) as affected by organic matter remain unclear. The accumulation, transformation, and migration characteristics of soil P in different soil layers of vegetable fields were researched under the application of organic materials. Six treatments were set up in the experiment:control (no fertilization), traditional fertilizer application by farmers, biochar, chicken manure, food waste, and straw application. Available phosphorus (Olsen-P), water-soluble phosphorus (CaCl 2 -P) content, soil phosphorus forms, soil organic matter (SOM), and pH were determined during the pepper harvest period. In the 0-5 cm and 5-10 cm soil layers, the available phosphorus content of traditional fertilization of farmers was higher, and the available phosphorus content of the four organic materials was in the order of straw > biochar > chicken manure > food waste. Compared to that with food waste, the straw and biochar treatments increased soil available phosphorus by 59.6%-67.3% and 29.1%-36.9%, respectively. The straw treatment could easily enhance the soil labile P pool, and soil labile P in the 0-5 cm soil layer increased by 47.3% and 35.1% compared with that under the chicken manure and food waste treatments, respectively. With the increase in soil depth, the proportion of available phosphorus in the chicken manure treatment decreased the least, and available phosphorus of the 20-30 cm soil layer accounted for 55.9% of the topsoil layer but only accounted for 16.0%-34.0% under treatment with the other three materials. Compared with that under the traditional fertilization of farmers, the pH significantly increased by 0.18-0.36 units after the application of organic fertilizer, and the pH of the chicken manure and food waste treatments was significantly higher than that of biochar and straw ( P < 0.05). SOM content under the biochar treatment significantly increased by 7.7%-17.6% compared to that under the other three organic materials. Among the four organic materials, the straw treatment boosted the labile P pool the most, which was conducive to the rapid increase in plant-available P. Phosphorus was most likely to migrate downward under the chicken manure treatment. In the field management based on soil fertility enhancement, the application of biochar could not only improve soil pH and SOM but also avoid excessive accumulation of phosphorus in the surface layer, which decreases environmental risks.

In recent years, China has made great efforts to carry out source-separation in municipal solid waste management; in particular, the utilization of food waste has received increasing attention. Food waste-utilizing technologies, including anaerobic digestion, aerobic biological treatment, and insect feed conversion, are currently applied in China. However, in the existing cases, there were several disadvantages, such as a low rate of utilization, significant environmental impacts, poor economic benefits, etc., as well as a lack of systematic analysis and comprehensive assessment of the performances of food waste utilization technologies. In this study, a four-dimensional performance assessment method (resource efficiency, environmental impact, economic feasibility, and social effect, with 21 indicators) was established for assessing the life cycle process of food waste utilization technologies. We collected detailed information of 14 typical food waste utilization cases in China, and the results showed that the average scores of anaerobic digestion and insect feed conversion were 58.39 and 59.65, higher than those of the aerobic biological treatment (49.16). The highest scores among all subdivision technologies were centralized black soldier fly conversion and mesophilic wet anaerobic digestion, which were 67.14 and 60.82, respectively. With respect to the technologies of different treatment capacities and distribution modes, i.e., centralized and decentralized technologies, the resource efficiency and economic benefit scores of the former were 13% and 62% higher than those of the latter, whereas the environmental impacts and social effect scores of the latter were 8% and 34% greater than those of the former, respectively. In practice, the utilization technology of food waste should be chosen according to local conditions, such as the physical and chemical properties of food waste, the classification of municipal solid waste, financial affordability, collection and transportation distance, etc.

Objective: To analyze the situation and influencing factors of school meals leftover among primary and secondary school students in the area of the Nutrition Improvement Program for Rural Compulsory Education Students, improve the quality of school meals, develop healthy dietary behavior, and reduce food waste. Methods: In 2019, among the 50 monitoring counties that implemented the Compulsory Education Student Nutrition Improvement Program, two primary schools and two junior schools were randomly selected according to different food supply patterns.This study randomly selected one or two classes from grade 3 to grade 9. Basic information and school meals of 26 778 students were collected by using a student questionnaire. Multivariate logistic regression was used to analyze the influencing factors of leftovers rate. Results: 54.93% (14 709) of students wasted school meals, in which the highest rate was the staple food, with the main reason as "not in favor". 11.87% (1 743) of the students wasted school meals 6-7 days a week, with 54.20% (7 957) of students wasted but in less amount. The leftover rate of staple food was the highest (29.78%), followed by vegetables and meat. The main reason of leftovers was that they didn't like this kind of food (33.52%). The rate of school meal waste was higher for girls ( OR =1.19,95% CI :1.13-1.25), junior high school students ( OR =1.17, 95% CI : 1.11-1.25), resident students ( OR =1.06, 95% CI : 1.00-1.12), lower economic level ( OR =1.06, 95% CI : 1.00-1.12), parents working outside their houses ( OR =1.22, 95% CI : 1.13-1.30), health education classes ( OR =1.70, 95% CI : 1.40-2.06), company-based meals ( OR =1.89, 95% CI : 1.71-2.07) and school meals were not as good as home food( OR =1.89, 95% CI : 1.78-2.00)( P <0.05). Conclusions: It is common for poor rural primary and middle school students in central and western China to waste school meals, and the reasons were affected by many factors. Reducing food waste requires the joint efforts of individuals, families, schools and society.

Food wastes are rich in nutrients and can be used for producing useful chemicals through biotransformation. Some oleaginous microorganisms can use food wastes to produce lipids and high value-added metabolites such as polyunsaturated fatty acids, squalene, and carotenoids. This not only reduces the production cost, but also improves the economic value of the products, thus has large potential for commercial production. This review summarized the advances in food waste treatment, with a focus on the lipid production by oleaginous microorganisms using food wastes. Moreover, challenges and future directions were prospected with the aim to provide a useful reference for related researchers.

Loess is widely distributed in northwestern China. Due to the arid climate and rainstorm erosion, lack of nutrients and microorganisms, as well as severe salinization limits the ecosystem carrying capacity of loess soil, which has become one of the major causes of regional land desertification. The fermentation broth derived from food waste usually contains substantial organic acids and nutrients such as nitrogen and phosphorus, and it has the advantages of being easily produced industrially and applied as fertilizer. Hence, this broth has the potential to become a soil amendment for loess soils. This work studied the Lanzhou loess, which is a typical soil of the Loess Plateau of China, fertilized with fermentation broth for the evaluation of physicochemical properties and microbial analyses. After the application of the broth amendment, the total nitrogen, available phosphorus and potassium, and organic matter content increased by 363%, 577%, 308%, and 204%, respectively. After planting grass, including Halogeton arachnoideus Moq . and Medicago sativa L., the comprehensive soil fertility level was further improved and the total salt content of the soil was decreased by 2.3 g·kg -1 and 1.2 g·kg -1 , respectively. Meanwhile, the fermentation broth promoted the growth of microorganisms, including bacteria and archaea, which increased by 22 times, and fungi by 8.3 times. Therefore, food waste fermentation broth is conducive to further forming plant-microorganisms symbiosis, improving the ecological environment quality of loess soils.

A laboratory-scale anaerobic membrane bioreactor (AnMBR) was used for the co-digestion of sewage sludge and food waste to investigate its organic matter removal characteristics, biogas production performance, and microbial community composition. The results showed that the degradation rate of volatile solids (VS) increased from 17.5% for a single digestion to 40% for the total digestion, and that the COD removal was 95.3% when the organic loading rate (OLR) was stabilized at 0.59-0.64 kg·(m 3 ·d) -1 . The solids content of the digested sludge increased by a factor of 3.9. The final CH 4 content was 60% and the CH 4 yield was 78.7 mL·g -1 of COD added . The transmembrane pressure (TMP) and average flux were maintained at between -3.1 and -2.7 kPa and 0.106 L·(m 2 ·h) -1 , respectively, and membrane fouling was not serious. According to an analysis of the microbial diversity using 16S rRNA, the anaerobic bacterium in the AnMBR were mainly phylum Proteobacteria, Bacteroidetes, and Cloacimonetes, and the dominant methanogens included the Methanobacterium family, Methanosaeta genus, and Methanolinea genus. This study provides a strong theoretical basis for research into the stability and performance of AnMBRs for the co-treatment of sludge and other high-solid waste streams, and provided an effective solution for biomass resource utilization and the energy crisis.

Objective: To investigate occupational hazards in waste incineration power generation enterprises. Methods: From May 2016 to September 2018, four garbage incineration power generation enterprises in different regions and scales were selected as the survey objects. Investigated and analyzed the types of occupational hazards, workplace distribution and occupational disease prevention facilities and the concentration (intensity) of major types of work and workplace occupational hazards were also improved Line detection and analysis. Results: Silica dust could be seen in slag tank, slag sorting and crusher operation position. The concentration of silica dust in each workplace fluctuates within 0.3-1.1 mg/m(3). Both the concentration of silica dust in the workplace and the time weighted average allowable concentration (C-TWA) of dust exposure of dust exposed workers were detected, but none of them exceeds the requirements of the national occupational exposure limit. Carbon monoxide, ammonia, nitrogen dioxide, hydrogen sulfide, non methane total hydrocarbon, formaldehyde, hydrogen fluoride, hydrogen cyanide, hydrochloric acid, sodium hydroxide and ozone were detected, but all meet the requirements of national occupational exposure limit. The 8-hour equivalent a sound level (L(ex·8h)) over 85 dB (A) mainly includes boiler, steam turbine, electrical inspector and auxiliary value of water treatment. Conclusion: The occupational hazards of waste incineration power generation enterprises are serious. Occupational health management and occupational health monitoring to reduce their occupational hazards to workers.

The infection of blood-borne diseases in medical workers mainly caused by ampule bottles, injection needles, infusion needles, surgical blades and all kinds of medical sharp instruments. Standardize the usage of sharp collection box can effectively prevent sharp injury. However, it has been found some shortcomings in practice and the varieties are few and specifications are unitary. Therefore, the medical workers of general surgery department of Subei People's Hospital in Jiangsu Province designed a new type of sharp collection box, which is convenient to collect sharps and prevent stabs. It is safe and reliable. The product is a hard container, which composes of box body, funnel input port and collection box. The box body is used to hold sharps, and its upper part is a funnel-shaped sharps input port. In order to reduce the possibility of stab and recycle the dropped sharps, we designed a flanging around the funnel input port, which can prevent the sharps from falling. In addition, a transparent observation port is arranged at 3/4 of the sharps box volume, which can facilitate the timely disposure of sharps. Compared with the traditional sharps box, the new funnel sharps collection box can safely collect various medical sharps and reduce the stab probability and occupational exposure risk of medical personnel.

The composition of municipal solid waste (MSW) in landfills is complex; additionally, the waste stored in landfills continues to generate greenhouse gases, odors, and ground water pollutants even during the post-closure stage. Therefore, landfills are considered key fields of urban eco-environmental remediation. In this context, it is crucial to understand the storage, composition, physical, and chemical characteristics of waste, as well as its potential environmental impacts. However, very few studies have discussed these topics in detail. In this work, we focused on the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), which has the highest urbanization rate and population density of all China. The generation, stock, physical components, and key elements of MSW in eleven cities of the GBA were analyzed based on both the scientific literature and statistical data. The main results are as follows:① the total amount of MSW produced by the cities was of 26.4 Tg in 2017, with an average annual increment of 0.8 Tg; moreover, the most used disposal method was the sanitary landfill (58.9% of the total); ② the total amount of MSW disposed in the landfills was equal to 230.1 Tg[including mainly food waste (109.6 Tg), plastic (38.9 Tg), and paper (29.6 Tg)]; ③ between 2001-2017, a total of 50.0 Tg of carbon were input in the landfills in the form MSW, of which 7.1 Tg of carbon were emitted as gas and 1.5 Tg were discharged as leachate; moreover, the total landfill carbon stock was equal to 41.4 Tg. Overall, this study provides fundamental data that can be used to determine the environmental impacts of MSW landfills and implement the eco-environmental remediation of urban landfill sites in the GBA.

Two parallel digestion systems of food waste (FW) and waste-activated sludge (WAS) were successfully initiated using a continuous stirred-tank reactor (CSTR), and the effect of different reduction extents of sludge retention time (SRT) on the co-digestion of FW and WAS was investigated. SRT Reduction extents longer than 8.3 d were not conducive to the stable operation of the co-digestion system when the organic load rate (OLR) was increased. The reduction extent of SRT should be reduced gradually from 5 d to 0.9 d to achieve high load and stable operation of the co-digestion of FW and WAS. After a long-term operation (approximately 282 d), the co-digestion reached stable operation at SRT of 9.1 d and OLR (calculated by COD) of (12.9±1.5) g·(L·d) -1 . The corresponding methane production, methane yield (calculated by COD), pH, and volatile fatty acid (VFA, calculated by COD) were 3.94-4.25 L·(L·d) -1 , 288-302 mL·g -1 , 7.80-7.83, and 0.32-0.39 g·L -1 , respectively. Additionly, the sludge characteristics of the co-digestion of FW and WAS under a high loading rate were also investigated. The results showed that the primary pathway of methane conversion was through acetic acid during the co-digestion of FW and WAS. Meanwhile, higher methanogenic activity of acetic acid, propionic acid, butyric acid, valeric acid, and coenzyme F 420 concentration were also measured.

Using land use data in the year 1995, 2005 and 2014, this study estimated the ecosystem service value (ESV) in each county located in the middle reach of Yangtze River and analyzed its spatiotemporal variation features and terrain gradient effects based on "the equivalent value per unit area of ecosystem services in China". The results showed that ESV in the middle reach of Yangtze River was generally higher in mountainous area but lower in plain region, with an obvious terrain gradient effect. Specifically, the relationship of the relief degree of land surface (RDLS) and the ESV showed significant logarithm function at county scale with a high curve fitting degree of 0.53. The ESV increased from 400.35×10 4 yuan·km -2 to 554.57×10 4 yuan·km -2 with the increasing RDLS (grade 1-5) in 2014. During 1995-2004, the ecosystem service value variation changed from decreasing to stable with the increases of the RDLS. With a perspective of ecosystem service values, the value of food production and waste treatment service value decreased with the increase of the RDLS, while the others increased in general, such as the production of raw materials and gas regulation service value, because of the influences of dynamic land use structure in varied topography and distinct dominant ecosystem services from different land types.

Objective: To investigate the abnormalities of the blood system in landfill workers. Methods: A cohort study was conducted for 224 landfill workers who were followed up for 6 consecutive years with abnormal routine blood test results and a low platelet count as the outcome events. The life-table method was used to analyze the incidence rates of these two outcome events, and the incidence rates were compared between first-and second-line workers. Results: A total of 71 workers had abnormal routine blood test results, among whom 29 had abnormal leukocyte count, 14 had abnormal erythrocyte count, 40 had abnormal platelet count, 17 had abnormal hemoglobin, and 29 had a reduction in platelet count. For these landfill workers, the 6-year abnormal rate of routine blood test results was 43.2%, and the incidence rate of low platelet count within 6 years was 13.5%. The first-line workers had a significantly lower abnormal rate of routine blood test results than the second-line workers ( P =0.020) , and the relative risk of abnormal routine blood test results in the first-and second-line workers was 0.592. There was no significant difference in the incidence rate of low platelet count between the two groups of workers ( P ≥0.05) . Conclusion: The landfill has an adverse effect on the blood system of landfill workers, and the second-line workers have greater impairment than the first-line workers.

Landfills are the third largest iron reservoir and one of the largest sources of methane release. Iron, as a kind of transition metal, plays a particularly important role in environmental biogeochemistry and is closely linked to the biogeochemical cycle of C, S and N. The aged refuse could be utilized as bio-cover material to improve the removal of contaminants. Therefore, this work investigated the effect of iron reduction on anaerobic removal of methane, and the interactions of ferric iron with nitrate and sulfate in the aged refuse. The columns were operated as landfill bio-covers and recirculated leachate with addition of FeCl 3 solution. In the experiment, three columns were used, two of them were used as controls (named as B1 and B3), B1 was fed with leachate and CH 4 , whereas B3 was only recirculated with leachate adding FeCl 3 . The treatment B2 was fed with the above two substrates. During the operation of columns, the contents of CH 4 , CO 2 and N 2 in the gas, and the concentrations of NO 3 - , NO 2 - , NH 4 + , SO 4 2- , Fe(Ⅲ) and Fe(Ⅱ) in the leachate and refuse were respectively determined. The results showed that adding ferric iron obviously enhanced the removal of methane in anaerobic aged refuse, the decrease of methane content with time obeyed zero-order kinetic, and the rate of methane removal(denoted as CH 4 /aged refuse)reached 1.28 mmol·(kg·d) -1 . In the anaerobic condition, methane could improve the reduction of Fe(Ⅲ) to dissolved, active and bioavailable Fe(Ⅱ). The active Fe(Ⅱ) probably coupled to the transformation of NO 3 - and SO 4 2- , and thus accelerated the removal of NO 3 - and SO 4 2- .

To investigate the perennial effect of environment adjustment layers on the interior environment and nitrogen transformation in anaerobic bioreactor landfills, three sets of simulated anaerobic bioreactor landfills and two kinds of environment adjustment layers of mineralized refuse with heavy calcium carbonate (R2) and mineralized refuse with natural zeolites (R3) were designed and established. The degradation and transformation of nitrogen in waste and leachate had been monitored for 390 days. The results showed that, the value orders of pH, alkalinity, oxidation reduction potential and moisture content (MS) were pH(R2) > pH(R3) > pH(R1), alkalinity (R2) > alkalinity (R3) > alkalinity (R1), Eh(R2) < Eh(R3) < Eh(R1) and MS(R3) > MS(R2) > MS(R1). In R1, R2 and R3, the degradation rates of total nitrogen, ammonia nitrogen, nitrate nitrogen in waste were 79.2%, 82.3% and 88.5%, 48.3%, 60.1% and 67.7%, 38.5%, 44.2% and 53.4%, respectively. Concentration comparison results of total nitrogen, ammonia nitrogen and nitrate nitrogen in leachate were TN(R3) < TN(R2) < TN(R1)、NH 4 + -N(R3) < NH 4 + -N(R1) < NH 4 + -N(R2)NO 3 - -N(R3) < NO 3 - -N(R2) < NO 3 - -N(R1). Additionally, both of mineralized refuse with heavy calcium carbonate and mineralized refuse with natural zeolites could long-term adjust and optimize the interior environment of anaerobic bioreactor landfills for the degradation and conversion of nitrogen. Mineralized waste with natural zeolite could not only promote the degradation and transformation of nitrogen components in waste and leachate, but also control the accumulation of ammonia nitrogen through leachate recirculation.

Size fractionation and chemical composition of municipal solid waste incinerator (MSWI) fly ash were investigated. And the leaching efficiency of heavy metals was contrastively studied using toxicity characteristic leaching procedure (TCLP), European standard protocol (EN12457-2), sequential extraction procedure (SEP) and physiologically based extraction test (PBET) for different size-fractionated fly ash. The results indicated that the main compositing elements of fly ash were Ca, Si, Al, Mg, Fe, Na, K. 58.7% of fly ash particles were in the range of 38-106 μm and the amount in the<150 μm particle-size fraction accounted for more than 90% of in total, Cu, Pb and Cd mainly existed in the residual form with a minor amount of exchange fraction for any size-fractioned fly ash particles. TCLP result showed that leaching amounts of Zn, Cu and Pb, except for As and V, firstly increased and then decreased with the reduction of particle size. The leaching amount of Zn reached the highest value of 547 mg·kg -1 in the range of 38-106 μm, whereas the leaching amount of heavy metals exhibited a lower level for all size-fractioned fly ash particles. The extraction concentrations of Zn, Pb, Cu and As reached 3270, 339, 335 and 16.8 mg·kg -1 for the PBET tests, respectively, which were significantly higher than those of the TCLP. Therefore, heavy metals in MSWI fly ash had the potential bioavailability to human body.

Based on aerobic manure composting with or without the addition of a mixture of sulfadimethoxine SM2 and sulfamonomethoxine SMM (1:1, m/m), changes in the physic-chemical properties of manure compost, the microbial community physiological profiles, the antibiotics concentration and the abundances of five antibiotic resistance genes (ARGs) during the composting were tracked. The results indicated that the introduction of sulfonamide antibiotics led to inhibition on the basal respiration of manure compost during the early composting period, delayed the formation of thermophilic temperature and reduced the conversion of nutrients such as organic matter, ammonia nitrogen and nitrate nitrogen. Meanwhile, the introduction of sulfonamide antibiotics dramatically affected the physiological profile of microbial community in manure in the middle stage of composting. HPLC-MS/MS results showed that both SMM and SM2 in manure were completely degraded within 14 days, while the degradation rate of SMM was faster than that of SM2. For both composting treatments with or without addition of exogenous antibiotics, the relative abundance of sull and sul2 showed an initial decline in the first 14 or 21 days and a slight increase thereafter. The addition of exogenous antibiotics showed insignificant enhancement on increasing the relative abundance of sul1 and IntI1 in manure, but resulted in an apparent increase in sul2 relative abundance. Although the fates of tetQ and tetW during composting were different from that of sulfonamide ARGs, the introduction of sulfonamide antibiotics into manure increased the relative abundance of tetracycline ARGs. Redundancy analysis indicated that composting temperature correlated negatively with sul1, sul2 and IntI1 relative abundance in manure but had no obvious relationship with tetQ and tetW relative abundance. All the ARGs detected in this work correlated negatively with C/N ratio and the nitrate nitrogen concentration of manure compost but positively correlated with pH, moisture and ammonia nitrogen concentration of manure compost.

Mature landfill leachate, featured with high ammonium (NH4+) content and low biodegrade ability (low BOD5/COD ratio), is hard to be treated. This study mainly focused on the effects of influent TN (total nitrogen) loading and BOD5/TN ratios on the nitrogen removal efficiency of landfill leachate by landfill bioreactors. The results showed that when the influent total nitrogen loading was in the range of 15 g x (m3 x d)(-1) to 25 g x (m3 x d)(-1), the TN removal loading could remain stable between 10 g x (m3 x d)(-1) and 12 g x (m3 x d)(-1), while the TN removal efficiency decreased from 67.7% to 60.2% with the increasing loading. Therefore, TN loading shocks would lower the bioreactor's TN removal rate, but would not affect its TN removal loading. When the influent BOD5/TN ratio was increased from 0.3 to 0.4 and the TN loading was controlled at 9 g x (m3 x d)(-1), the TN removal rates were increased from 79.9% to 89.9% and 86.2% in anaerobic and aerobic, respectively. This implied that properly enhancing BOD5/TN ratio could significantly increase the TN removal efficiency of the bioreactor, and the effect was more significant under anaerobic condition. Analysis of nitrogen removal pathways showed that denitrification and anammox could take place synergistically in landfill bioreactor.

To study the effects of superphosphate (SP) on the NH, and greenhouse gas emissions, vegetable waste composting was performed for 27 days using 6 different treatments. In addition to the controls, five vegetable waste mixtures (0.77 m3 each) were treated with different amounts of the SP additive, namely, 5%, 10%, 15%, 20% and 25%. The ammonia volatilization loss and greenhouse gas emissions were measured during composting. Results indicated that the SP additive significantly decreased the ammonia volatilization and greenhouse gas emissions during vegetable waste composting. The additive reduced the total NH3 emission by 4.0% to 16.7%. The total greenhouse gas emissions (CO2-eq) of all treatments with SP additives were decreased by 10.2% to 20.8%, as compared with the controls. The NH3 emission during vegetable waste composting had the highest contribution to the greenhouse effect caused by the four different gases. The amount of NH3 (CO2-eq) from each treatment ranged from 59.90 kg . t-1 to 81.58 kg . t-1; NH3(CO2-eq) accounted for 69% to 77% of the total emissions from the four gases. Therefore, SP is a cost-effective phosphorus-based fertilizer that can be used as an additive during vegetable waste composting to reduce the NH3 and greenhouse gas emissions as well as to improve the value of compost as a fertilizer.

In order to study the effects of upper-layer aerobic pretreatment in bioreactors on refuse degradation, leachate condition and methane production, two simulated columns were constructed, including traditional anaerobic bioreactor A1 and hybrid bioreactor C1 with aeration pretreatment in the upper layer. Results indicated that A1 was seriously inhibited by the accumulation of volatile fatty acids (VFA) with nearly no methane production and slower settlements. At the end of operations, refuse in A1 only deposited 5.4 cm which was less than half of that in C1. And up to 70 000 mg x L(-1) COD and 30 000 mg x L(-1) VFA could be monitored in the leachate. On the contrary, aerobic pretreatment effectively improved the removal of high VFA concentrations and remarkably accelerated the degradation rate. In bioreactor C1, COD and VFA concentrations were reduced to less than 14000 mg x L(-1) and 8900 mg x L(-1) at the end of the experiment, respectively. And about 61 976 mL methane gases were produced since aeration ceased on day 60 with its methane recovery efficiency rising to over 95%. However, the performance of hybrid bioreactors was still closely related to its operation conditions, such as aeration supply and leachate recirculation. Therefore, in order to guarantee better performance, appropriate aeration and leachate operations need to be provided.

Nitrous oxide (N2O) is one of three major greenhouse gases and the dominant ozone-depleting substance. Landfilling is the major approach for the treatment and disposal of municipal solid waste (MSW), while MSW landfills can be an important anthropogenic source for N2O emissions. Measurements at lab-scale and full-scale landfills have demonstrated that N2O can be emitted in substantial amounts in MSW landfills; however, a large variation in reported emission values exists. Currently, the mechanisms of N2O production and emission in landfills and its contribution to global warming are still lack of sufficient studies. Meanwhile, obtaining reliable N2O fluxes data in landfills remains a question with existing in-situ measurement techniques. This paper summarized relevant literature data on this issue and analyzed the potential production and emission mechanisms of N2O in traditional anaerobic sanitary landfill by dividing it into the MSW buried and the cover soil. The corresponding mechanisms in nitrogen removal bioreactor landfills were analyzed. Finally, the applicability of existing in-situ approaches measuring N2O fluxes in landfills, such as chamber and micrometeorological methods, was discussed and areas in which further research concerning N2O emissions in landfills was urgently required were proposed as well.

The generation and variation of the secondary pollutants in containers during seasons of a year were investigated in a municipal refuse transfer station of Shanghai. The results showed that the primary odors, the concentration of H2S was in a range of 0.3-10.3 mg.m-3, CH4 was in a range of 0.02% -2.97% and NH3 was in a range of 0.7-4.5 mg m-3, and their concentrations all reached the peak in the summer. The pH of the leachate was in a range of 5.4-6. 3, COD was 41 633-84 060 mgL- 1, and BOD, was 18 116-34 130 mg.L , the concentration of pollutants were all higher in winter than that in summer. The ammonia concentration of leachate was in a range of 537-1222 mg.L'', while the TP fluctuated acutely in a range of 17.98-296 mg L-1, exhibiting the relationship with seasonal variation. Extreme temperatures especially the high temperature in summer significantly affected air pollution producing, which indicated that containers should be kept against high temperature exposure and long residence time in order to prevent flammable gases and other pollutants generated largely.

It is practically important that high concentrations of organic pollutants in landfill leachate were degraded by a rapid and efficient approach. The influence of operating conditions such as schwertmannite dosage, V(H2O2)/m (schwertmannite) ratio on the degradation efficiency of color, TOC and COD contents of landfill leachate, was investigated by using the schwertmannite/H2O2/UV process. It was demonstrated that the color, TOC and COD removal efficiencies increased significantly with the increase in schwertmannite dosage, and then were approximately stable. However, COD removal efficiency declined because of the presence of the residual H2O2 when V (H2O2)/m (schwertmannite) was greater than 2, and the best removal efficiency of COD was 44.9%. Furthermore, high-intensity ultraviolet was more conducive to eliminate pollutants through photochemical oxidation with schwertmannite/H2O2. The color, TOC and COD removal efficiencies were 90.0%, 78.8% and 52.6% respectively after 2.5 hours of photochemical degradation, with UV-500 W under optimal initial pH = 2.5; meanwhile, this study found that it was beneficial to the photochemical degradation of leachate at room temperature via the schwertmannite/H2O2/UV process, and COD removal efficiency declined gradually when the temperature was higher than 25 degrees C. Controlled trials showed that the schwertmannite/H2O2 method was conducive to the removal of color compared with the traditional homogeneous Fenton reaction.

In order to investigate the groundwater pollution by landfill leachates, the distribution characteristics of inorganic salt, organic compounds and heavy metals in leachastes from a simple landfill and groundwater and its reason were study using conventional analysis, fluorescence excitation-emission matrix spectra and multivariate statistical analysis. The results showed that the landfill was heterogeneous, and the extracts from the landfill wastes showed a high concentration of NH4(+) -N, but low contents of Cl-, SO4(2-), dissolved organic matter (DOM) and heavy metals. The nitrification process was blocked due to a strong reducing atmosphere in landfill, which caused a low concentration of NO3(-) -N and NO2(-) -N in leachates. Cu was mainly associated with DOM in leachates, while the distribution of the metals Ba, Cd, Cr, Fe, Mn, Ni, Zn and As was primarily related to hydrophobic organic compounds. The contaminate compositions in different groundwater were similar except for the groundwater under the landfill site. In contrast to landfill leachates, the groundwater showed a low concentration of NH4(+) -N, but high concentrations of Cl-, SO4(2-), DOM, NO3(-) -N and NO2(-) -N except for the groundwater under the landfill site. The organic compounds in the groundwater were mainly originated from microbial activity, and the distribution of the metals Ba, Cd, Cu, Fe, Mn and Ni was mainly related to fluorescecent organic matter in DOM. The results showed that the leak point of landfill leachates can be identified through the cluster analysis method on the basis of the contaminant composition in groundwater.

Emission rates of volatile organic compounds (VOCs), H2S and odor unit from the surface of a municipal solid waste (MSW) landfill working area were measured with a wind tunnel sampler. The results show that the emission rate of odor from the non-point source of landfill is the function of environmental temperature and surface sweeping velocity. The emission rate measured in the high temperature season can be 6 times higher of that in the low temperature season. Within the experimental range of 0.6-4 m x s(-1) wind sweeping velocity, the emission rate shows a linear relationship with wind sweeping velocity. In summer, the emission rates of VOCs (measured by PID as isobutylene), H2S and odor unit are 385-680 microg x (m(2) x s)(-1), 4-7 microg x (m(2) x s)(-1), and 46.5-136 OU x (m(2) x s)(-1) respectively. The continuous sweeping experiment shows that the emission rate measured with clean air sweeping is the maximum possible emission rate, which needs to be adjusted when it is used to estimate the odor concentration of more than 10 min sample time or an area emission load.

A pot experiment was conducted to evaluate the effects of herb residue vermicompost on maize growth and soil fertility. With the increasing application rate of vermicompost, the plant height, stem diameter, leaf area, and chlorophyll content of maize all increased significantly. After 60 days growth of maize, the soil bulk density in most vermicompost treatments decreased significantly. The soil pH in vermicompost treatments was significantly higher than that in CK and in chemical fertilization treatments. In addition, the soil total nitrogen and organic matter contents in vermicompost treatments were obviously higher than those in chemical fertilization treatments. It was suggested that herb residue vermicompost could be used as an efficient and high-quality organic fertilizer, and its appropriate application could improve soil physical structure, alleviate soil acidification, increase soil organic matter and nitrogen contents, and promote crop growth.

The production of biochar by pyrolysis and its application to soil can sequester the CO2 which was absorbed by plants from atmosphere into soil, in addition it can also bring multiple benefits for agriculture production. On the basis of the available potential survey of the biomass residues from agriculture and forestry section, life cycle assessment was employed to quantify the potential of biochar technology in mitigation of greenhouse gases in our country. The results showed: In China, the amount of available biomass resource was 6.04 x 10(8) t every year and its net greenhouse effect potential was 5.32 x 10(8) t CO(2e) (CO(2e): CO2 equivalent), which was equivalent to 0.88 t CO(2e) for every ton biomass. The greatest of contributor to the total potential was plant carbon sequestration in soil as the form of biochar which accounts for 73.94%, followed by production of renewable energy and its percentage was 23.85%. In summary, production of biochar from agriculture and forestry biomass residues had a significant potential for our country to struggle with the pressure of greenhouse gas emission.

In order to analyze the effects of electrical resistivity in heavy metal contaminated sites, we established the resistivity model of typical contaminated sites and simulate the DC resistivity method with Wenner arrays using the finite element method. The simulation results showed that the electrical method was influenced by the contamination concentration and the location of pollution. The more serious the degree of pollution was, the more obvious the low resistivity anomaly, thus the easier the identification of the contaminated area; otherwise, if there was light pollution, Wenner array could not get obvious low resistivity anomalies, so it would be hard to judge the contaminated area. Our simulation results also showed that the closer the contaminated areas were to the surface, the more easily the pollution was detected and the low resistivity anomalies shown in the apparent resistivity diagram were influenced by the Layered medium. The actual field survey results using resistivity method also show that the resistivity method can correctly detect the area with serious pollution.

Physico-chemical properties of broken bricks (BB) were determined, as well as its phosphorus adsorption ability. The results showed that BB was appropriate for enrichment of microorganisms and growth of plants as filter medium in CWs, in addition, BB had high phosphorus adsorption ability. A vertical subsurface flow constructed wetland (VSSF) filled with BB was constructed in order to investigate the phosphorus removal effect of domestic sewage, and the phosphorus removal mechanism of VSSF was also explored. The results showed that the phosphorus removal rate of VSSF was more than 90%, which remained stable when the hydraulic loading rate was 5 cm x d(-1) and the running time was 1 a; adsorption and precipitation within BB played the greatest role in phosphorus removal; distribution characteristics of total phosphorus in the filter media were attributed to the vertical flow state of wastewater in the system, besides, the contents and chemical forms of elements which could precipitate with phosphorus should be principal factors for the phosphorus removal processes of BB. Therefore, BB might be an ideal filter medium used in CWs.

The Anaerobic-semiaerobic Bioreactor Landfill (AN-SABL) has been devised combining an Anaerobic Bioreactor Landfill (ANBL) with a Semi-aerobic Aged Refuse Biofilter (SAARB) for reducing the investment and the running expense. It was a novel bioreactor landfill which could accelerate the stabilization of waste obviously. The evolution of leachate quantity and quality for the AN-SABL was studied in order to provide a theoretical basis for the management and treatment of leachate. The results indicated that the quantitative reduction of leachate in the AN-SABL was obvious and the highest reduction could reach by 771 g x kg(-1). Moreover, the quality of leachate varied in phases. The concentration of nitrate including nitrite and ammonium was influenced markedly by Eh and pH. At the end of the experiment, the removal rates of COD for the AN-SABL2 and the AN-SABL3 reached by 98.49% and 97.98% and the concentrations of COD were only 14.5% and 21.1% of that in leachate from the ANBL1 respectively. Therefore, the organic matter could be degraded completely with the AN-SABL. Besides, the AN-SABL could remove the nitrogen pollutant effectively as well. The concentrations of ammonium in leachate from the AN-SABL2 and the AN-SABL3 decreased obviously from the maximum of 1 452 mg x L(-1) and 1 409 mg x L(-1) to 525 mg x L(-1) and 459 mg x L(-1) respectively which only were 36.5% and 31.9% of that in leachate from the ANBL1. For the SAARB unit, the TOC and TC ratio played a vital influence on the removal efficiency of the organic matter and nitrogen pollutant. After the TOC and TC ratio declined to about 0.2, the removal rate of COD and TN for SAARB decreased from over 95% and over 93% to 35.25% -69.56% and 64.53% -77.45% respectively.

This study kinetically investigated landfill leachate rejected by reverse osmosis (RO) oxidation degradation by ozonation. Initial pH, ozone dosage, temperature and initial COD had significant impact on the oxidation rate. The results demonstrated that for the removal efficiencies of COD 67.6% under the conditions of 8.0 pH, 5.02 g/h ozone dosage, 303K temperature. The empirical kinetic equation of ozonation degradation for landfill leachate under the conditions of 2.0-8.0 pH, 2.53-6.90 g/h ozone dosage, 934-4 037 mg/L initial COD, 283-323 K temperature fitted well with the experimental data(R2 0.969-0.996), with low activation energy E(a) = 1.43 x1094) J x mol(-1).

Objective: To determine occupational hazards in work sites of a large solid waste landfill and analyze their adverse health effects., Method: The national standardized detection methods were used to determine dust concentration, harmful gas and physical factors in worksites. Routine physical examination, pulmonary function, hearing tests and nervous system test were performed in workers for 2 consecutive years. Urine lead, cadmium and mercury contents were detected. The comet assay was use to measure DNA damage in peripheral blood lymphocytes among workers., Result: The main occupational hazard factors in this solid landfill are dust, harmful gas, high temperature and noise. The oxides, carbon monoxide, and noise and high temperatures in summer at some work sites exceeded the national occupational exposure limits. The prevalence of respiratory inflammation and rate of pulmonary function decrease among front-line workers and on-site technical managers are 21.2% and 11.5%, which are significantly higher than those among administrative staff (7.1% and 0) (P < 0.05). Nervous system abnormalities rate of front-line workers and on-site technical managers was 50.0%, which is significantly higher than that (26.7%) of administrative staff (P < 0.05). Because of long-term exposure to high intensity noice, hearing loss rate of bulldozer drivers was 10.3%. In addition, about 75% of workers with DNA damage in peripheral blood lymphocyte are front-line workers., Conclusion: Adverse health effects from occupational hazards were observed among workers in this solid waste landfill.

The odor pollution of landfill is one of seriously pollutions in city ambient area. Main pollution points in the landfill area have been detected by preliminary research. For a particular purpose to recover the materials changing in odor dispersion process and to find out odor indication material, GC-MS method was used to detect materials in the different site at down wind direction. Then, similarity coefficient of VOCs (volatile organic compounds) composition between every two site were calculated and compared to look for changing regular of odor pollution in diffusion process. The odor pollution indictor material has be found in the materials that appeared in down wind direction of operation area and compared its' olfaction threshold. The results show that: there have 19 types of common materials in the landfill area, including monoaromatics, alkanes and halogenated compounds; Materials in the air of operation area site has marked influence on down windward direction air of landfill, and m-xlyene has been selected as odor pollution indictor of landfill air by this research.

Pyrolysis of cellulose with different catalysts has been conducted in a fixed-bed reactor. Micro-mesoporous composite molecular sieves of ZSM-5(38)/A1-MCM-41 with different Si/A1 ratios were prepared under hydrothermal conditions. With powder X-ray diffraction (XRD), the catalyst samples were characterized. GC-MS was used to analyze the bio-oil composition. The effects of catalysts on the pyrolysis product yields were investigated and the results were compared with the results of experiments performed without catalyst under the same pyrolitic conditions. The presence of the catalysts decreased the liquid yield, while increased the moisture content. The major improvement in the quality of bio-oil with the use of catalysts was the increase of DL-2,3-Butanediol. ZSM-5(38)/A1-MCM-41(20) favored the formation of phenol and 2-methoxy-phenol. In addition, these catalysts were all benefit for the generation of small molecular compounds. Also, it was found that ZSM-5(38) was better for the production of C4-C5 compounds. And micro-mesoporous composite molecular sieves mainly promoted the production of C6-C8 compounds.

In order to explore the ways for promoting litter decomposition in urban protective greenbelts of arid zone, litter falls were collected from the protective greenbelts in north suburb of Karamay, Xinjiang, and a composting experiment with the inoculation of three kinds of microbial agents, i.e., Qingzhu, Jiegan, and Sufu, was carried out for 198 days in late October 2007. At the early stage (0-30 d) of composing, inoculating microbial agents promoted the decomposition of the litter falls, and the effect of Sufu agent was significant, compared with CK. The N, P, and Ca concentrations in the composing litter falls increased persistently with time. By the end of the experiment, the nutrient concentrations in the composed litter falls were 14.2%-252.9% higher than their initial values. During the whole composing process, the decomposition rate of the litter falls organic C increased continuously, and the C/N ratio decreased gradually. It was suggested that inoculating microbial agents could accelerate the composting process, and increase the nutrient concentrations in composted litter falls. Among the three test microbial agents, Jiegan agent was the best one.

In recent years, great attention has being paid on the consequences of improper electric and electronic waste (e-waste) disposal. In this paper, soil and plant samples were collected from the e-waste recycling sites in Taizhou City of Zhejiang Province, China, with five kinds of phthalic acid esters (PAEs) analyzed. In the soil samples, the total PAEs concentration was 12.566-46.669 mg x kg(-1) soil, among which, di-(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), and diethyl phthalate (DEP) were the major phthalates, accounting for more than 94% of the total. In the plant samples, the PAEs concentration was obviously higher in Vicia faba L. than in other plants. No significant correlations were observed in the PAEs concentration between soils and various plants (P > 0.05). Comparing with the soil cleanup guidelines in USA, the soils at test sites were severely contaminated by PAEs.

Twenty-four indoor and fifteen outdoor dust samples were collected from an electronic waste (e-waste) area, South China in October 2006 and October 2007 and analyzed for seventeen PBDE congeners. PBDEs were detected in all dust samples. The total PBDE concentrations for indoor dusts ranged from 230-157500 ng/g, with a mean value of 9 400 ng/g, and 212-25 880 ng/g, with a mean value of 3 311 ng/g for outdoor samples, respectively. The PBDE concentrations in the present study were at the high end of the worldwide figures. BDE209 was the predominant congener. Comparison of the PBDE congener patterns in dusts and technical products suggests that the relatively high abundances of octa- to nona-PBDE congeners in the dusts might be originated from the degradation of BDE209. The average exposure estimates of PBDEs via dusts are 470, 329 and 188 ng/d for infants, toddlers and adults, respectively. The highest exposure estimates for infants and toddlers (31 500 and 19 700 ng/d) were 4 and 2.5 fold higher than those for adults. These results indicate that dust may be a very important route of exposure for PBDEs in local residents.

The environmental availability of heavy metals from the waste printed circuit boards (PCBs) were studied through BCR's three-stage extraction procedures from EU and Tessier's five sequential extraction procedures. The results show that the heavy metal extraction rates with BCR's procedures are higher than that with Tessier's from waste PCBs. There are significant differences in fraction distributions of heavy metals in PCBs. The speciation of Ni in the PCBs exists mainly in residual forms and has little effect on the environment. The percentage of acidic extractable forms with BCR's method and the total amount of exchangeable and carbonate which bound for Tessier's procedure of Pb and Zn are high, in the South China, the two metals are more easily released by acid rain. Acidic extractable forms of Cu is the main speciation in PCBs with BCR's extraction procedures, while the percentage of Fe-Mn oxides- bound of Cu is the highest with Tessier's procedures, though the result is not agree consistent, due to the high content of Cu in PCBs, the harm of Cu from PCBs could not be neglected.

Objective: To investigate the smoking or age impact on occupational workers in electrical and electronic equipment waste (e-waste) dismantling procedure, using 8-Hydroxy-2'-deoxyguanosine (8-OHdG) in the urine as a biomarker for oxidative damage to DNA., Methods: The pre-workshift and post-workshift urinary samples of 64 male workers in e-waste dismantling procedure were detected by solid-phase extraction-high performance liquid chromatography-electrochemical detector (SPE-HPLC-ECD). The data were statistically analyzed by two factors, age or smoking status., Results: The 8-OHdG levels in non-smokers' urines (n = 42) were higher than those in smokers' urines (n = 22). The levels in pre-workshift urines were detected at (8.25 +/- 4.23) micromol/mol creatinine in non-smokers, while the values were (5.44 +/- 1.18) micromol/mol in smokers. And, the levels in post-workshift were detected at (43.12 +/- 16.19) micromol/mol creatinine in non-smokers, while the values were (14.82 +/- 2.51) micromol/mol in smokers. The 8-OHdG levels in pre-workshift urines were not different between non-smokers and smokers (t = -0.81, P = 0.42), however after 1 day exposure, urinary 8-OHdG levels were significantly increased in non-smokers than those in smokers (t = - 2.33, P < 0.05). On the other hand, the subjects were divided into five groups according to their age. The 8-OHdG levels in pre-workshift urines were (1.86 +/- 0.66), (3.57 +/- 0.54), (8.12 +/- 4.10), (11.39 +/- 3.70) micromol/mol creatinine in < 20 years group (n = 6), 20 -years group (n = 22), 30 - years group ( n = 23), 40 - 49 years group (n = 11) respectively. No effect of age was found on the pre-workshift urinary 8-OHdG levels (F = 0.98, t = 0.41). However, it was found that the post-workshift urinary 8-OHdG levels increased along with the e-waste workers' age (F = 4.81, P = 0.03), and they were (4.19 +/- 2.85), (19.89 +/- 5.26), (28.89 +/- 14.61), (34.94 +/- 12.50) micromol/mol creatinine in < 20 years group, 20 - years group, 30 - years group, 40 - 49 years group respectively., Conclusion: The urinary 8-OHdG levels in the e-waste dismantling workers might be inhibited by smoking status. The post-workshift urinary 8-OHdG levels increased along with the e-waste workers' age.

The purpose of this paper is to evaluate the hazardous of heavy metals of waste printed circuit boards (PCBs) by using four kinds of methods (GB 5086.1-1997, GB 5086.2-1997 from China and 1311 (TCLP), 1312 (SPLP) from USA), and the four kinds of methods are compared to choose a better way to identify toxicity characteristics of waste PCBs. The results show that the leaching concentrations of heavy metals (Cu, Pb, Ni, Mn, Zn and Fe) in the leachate after TCLP are much higher than that after the other three kinds of methods, the concentration of Pb is over the standards, so the waste PCBs may be the hazardous solid waste, the TCLP could be the appropriate way to assess the heavy metals hazardous characteristics of waste PCBs. The leaching concentrations by the leaching methods used in China are relatively lower, which could be disadvantageous to control the hazardous wastes. The initial pH and particle size of waste PCBs have great effect on the leachability of heavy metals from waste PCBs.

The effect of soil properties on N2O emissions and ammonia volatilization after leachate addition was investigated by soil S1 and S2 through incubation experiment. The conversions of soil NH4(+)-N and NO3(-)-N contents after leachate addition were evaluated as well. Soil pH dominantly determines the ammonia volatilization after leachate addition and ammonia volatilization only happens by soil S1 of alkaline nature within the first 5-day during the 10-day incubation. Approximately 3.0% leachate ammonia-N is lost via ammonia volatilization from soil S1. After being added the same amount of leachate ammonia-N, there is an approximately 20-fold gap of N2O emissions between two different soils: soil S1 and S2 (p <0.01). Soil moisture content affects the net generation rate of NO3(-)-N contents substantially and N2O fluxes are thus regulated accordingly. Compared with soils moisture content at water-filled pore space (WFPS) of 46%, N2O fluxes are elevated by 6.5, 1.8, and 2.2 times from the leachate added soil S1 without leachate irrigation (p > 0.05), the leachate added soil S1 (p > 0.05), and the leachate added soil S2 (p <0.05), respectively. During the 10-day incubation, N2O emissions cause 41.1% and 2.3% leachate NH4(+)-N loss from the leachate added soil S1 and S2, respectively. Therefore, avoiding excessively wet conditions (< 70% WFPS) and selecting acidic soil could minimize the potential N2O emissions and ammonia volatilization under leachate irrigation.

A system consisting of a two-stage UASB and anoxic-oxic reactor was used to study the influence of FA on short-cut nitrification of the actual municipal landfill leachate with high ammonia concentration. In the UASB1, denitrification and methanogenesis took place simultaneously. The effluent COD of UASB1 was further removed in the UASB2. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD and nitrification was finished in the A/O reactor. The experiment experienced three stages during 79 d. The stable short-cut nitrification was achieved in the first stage (40 d). The short-cut nitrification was damaged in the second stage (19 d), and the short-cut nitrification was recovered in the last stage (20 d). The results of 79 d showed that when the FA concentration was about 40-70 mg x L(-1), the stable short-cut nitrification could be achieved. For example, the nitrite accumulation was 97% in the system during the first stage, and the ammonia removal efficiency was 99%. But when the FA concentration was about 160 mg x L(-1), the nitrification would be inhibited. In the third stage, raw leachate was diluted by tap water in order to decrease the FA concentration. And then the short-cut nitrification was recovered soon. In a word, the FA concentration is an important factor to achieve the short-cut nitrification of the municipal landfill leachate.

The experiments focused on comparing the removal efficiencies of organic matters in fresh and mature landfill leachate by Fenton treatment. The changes in dissolved organic matter before and after Fenton treatment were assessed using gross organic parameters such as organic compound relative molecular mass (Mr) distribution, chemical oxygen demand (COD), total organic carbon (TOC) and the ratio of COD to TOC. The results from this study demonstrate that high Mr fractions of mature landffill leachate are more easily converted into dissolved small Mr fractions (Mr < 10(3)) by Fenton reaction than those of fresh landfill leachate, since the average Mr of mature landfill leachate is higher than that of fresh landfill leachate and the Mr > 10(5) fraction of the mature leachate account for 64% of the total mass. Operating parameters such as pH, [Fe2+] and [H2O2]/[Fe2+] demonstrate that the COD removal efficiency of the fresh landfill leachate (from 61% to 84%) is higher than that of the mature landfill leachate (from 31% to 60%), while it is converse for TOC (from 85% and 52% to 91% and 80% for the mature and fresh landfill leachate, respectively). Oxidation seems to play a more active role in COD reduction than coagulation whatever for the mature or fresh landfill leachate. Oxidation efficiency apparently controls coagulation efficiency, so that high oxidation efficiency may cause relatively low coagulation. The mass balances indicate that TOC removal by oxidation (TOCoxid) is more than COD removal by oxidation (CODoxid) for the mature landfill leachate while TOCoxid is less significantly than CODoxid for the fresh landfill leachate. The COD/TOC ratios are 1.17 and 1.58 for the initial mature landfill leachate and fresh landfill leachate, respectively, but they are 1.96 and 0.68 after Fenton treatment by oxidation, respectively. This phenomenon suggests that complete oxidations occur in the mature landfill leachate while both partial and complete oxidations occur in the fresh landfill leachate. The changes of CODcoag and TOCcoag illustrate that the oxidation state of the organic matters removed by coagulation in the mature landfill leachate is significantly lower than in the fresh landfill leachate.

By using prefabricated probe and static chamber, the N2O concentration at different depths along the soil columns irrigated by landfill leachate as well as the N2O and CO2 fluxes were determined. The results showed that leachate irrigation could promote the N2O emission. Within the first 24 hours after irrigation, the N2O fluxes from the soil columns were significantly correlated with the N2O concentrations in the columns at the depths of 10 cm (r = 0.944, P < 0.01), 20 cm (r = 0.799, P < 0.01), 30 cm (r = 0.666, P < 0.01), and 40 cm (r = 0.482, P < 0.05), and the correlation decreased along the depths. Landfill leachate irrigation also promoted the CO2 emission from the soil columns. There was no significant correlation between the emissions of N2O and CO2 (P > 0.05). The irrigation loading of landfill leachate had a predominant effect on the total greenhouse gas emissions (including N2O and CO2 fluxes, based on CO2-equivalent emissions). When the irrigation loading was 6 mm x d(-1), the total greenhouse gas emissions from the soil columns were 2 times higher than those when the irrigation loading was 2 mm x d(-1). 47% of the total greenhouse gas emissions were reduced from the soil columns when the leachate irrigation depth was at 20 cm, compared with the depth being at 10 cm. Within the 14 days under leachate irrigation, 57.0%-91.0% of the total greenhouse gas emissions were originated from N2O emission.

By the method of static chamber, the seasonal and diurnal variations of N2O fluxes in two full-scale municipal solid waste (MSW) landfills covered with sandy and clay soils were measured to study the effects of leachate irrigation and cover soil type on the landfill N2O emission. The results showed that the N2O flux in the MSW landfill covered with sandy soil was (242 +/- 576) microg N2O-N x m(-2) x h(-1) in summer, being 3.2 times (P > 0.05) as high as that in spring [(74.4 +/- 314) microg N2O-N x m(-2) x h(-1), while the N2O flux in the MSW landfill covered with clay soil was (591 +/- 767) microg N2O-N x m(-2) x h(-1) in summer, being 2.2 times (P < 0.05) as high as that in spring [(269 +/- 335) microg N2O-N x m(-2) x h(-1)]. Leachate irrigation promoted the N2O emission from the soil cover of the landfill covered with sandy soil, and the N2O flux in the landfill was 1 time higher than that of the control (P > 0.05). Under leachate irrigation, the average N2O flux in spring and summer in the landfill covered with sand soil was (211 +/- 460) microg N2O-N x m(-2) x h(-1), being only 1/2 of that [(430 +/- 605) microg N2O-N x m(-2) x h(-1)] in the landfill covered with clay soil without leachate irrigation (P > 0.05 ). Therefore, no matter leachate irrigation was conducted or not, the N2O emission from MSW landfill could be minimized by covering with infertile sandy soil.

A box filled with sandy soil was constructed to investigate dynamitic development and evolution of redox zones in landfill leachate-polluted plume. The results indicated that with time elapsing and pollution aggravating, redox zones moved ahead slowly; Methanogenic zone/ sulfate reduction zone extended gradually, and then inert zone appeared with further pollution. During the whole course of the dynamitic development and evolvement of redox zones, concentrations of TOC, sulfide, NH4(+) -N, HCO3-, CO2 and Fe2+ increased with time and decreased with distance; concentrations of NO3- and DO decreased with time and increased with distance; SO4(2-) concentration decreased first and then increased over time; but decreased with distance. Moreover, with time elapsing and pollution aggravating, the Fe3+ content of sediments was decrease and TOC was increase. Within oxygen reduction zone, nitrate reduction zone, iron reduction zone and methanogenic zone/sulfate reduction zone, Fe3+ content of sediments accounted for 70.5% of OXC decreased to 56.3%, 41%, 28.3% and 15%, and the TOC accounted for 98.7% of RDC increased to 102.0%, 107.0%, 142.9% and 162.1%, respectively; Fe2+ mainly precipitated as FeS and FeCO3, and accounted for 80.6%, 175.6%, 377.7% and 555.1% of total Fe2+, respectively.

The one-dimensional breakthrough soil column experiment and static experiment were constructed to investigate the spacial and temporal pH buffering capacity of the four natural geological media. Experimental results indicate that the background pH buffering capacity of fine sand, silt sand and clay is 79.9 x pH(-1) mmol/kg, 207.5 x pH(-1) mmol/kg, 456.4 x pH(-1) mmol/kg respectively. With the time going on and the distance closer to the leaching source, for each medium which is contaminated by the landfill leachate, the total pH buffering capacity decreases, the buffering capacity of calcium carbonate buffering system decreases, the buffering capacity of the silicate and cation exchange buffering system have no obvious changes, and the buffering capacity of the aluminium and ferric oxide buffering system also decrease, but the soil's buffering capacity of aluminium buffering system increases at first and then decreases. The temporal and spacial buffering capacity for each buffering system of the fine sand all increase appreciably. The order of the pH buffering capacity of the geological media on landfill leachate is fine sand < silt sand < clay < soil. The soil and clay have a good pH buffering capacity on landfill leachate as well as the controlling effect of the pollutants' transferring and diffusion.

In order to study whether disposing electronic wastes and secondary metal smelting could cause an arsenic pollution in the environment or not, Luqiao town, Taizhou City, Zhejiang Province was selected as a study area. The main purpose of this paper was to characterize arsenic contents in the local environment, including waters, sediments, soils and rice, and to assess the potential risk to humans. Additionally, the arsenic spatial distribution property and arsenic uptake-translocation rule in soil-rice system were also studied. The results showed that the average arsenic levels in the surface water and the groundwater were 8.26 microg/L and 18.52 microg/L, respectively, which did not exceed the limiting value of Chinese Environment Standards class III . Whereas,some groundwater exceeded the recommended standard by the WHO for drinking water (10 microg/L). The arsenic (on average 7.11 mg/kg) in paddy soils and arsenic (on average 6.17 mg/kg) in the vegetable garden soils were lower than the value recommended by the National Standard (level I). The average arsenic contents in brown rice and husks were 165.1 microg/kg and 144.2 microg/kg, which was also lower than the Chinese Foods Quality Standard. The arsenic contents between the corresponding soils-rice and husks-brown rice showed significantly positive correlations. By comparison, the arsenic contents of soils and husks collected around electroplating were relatively higher than most of other pollutant sources, indicating the electroplating may lead accumulation of arsenic in the paddy soil-rice system.