Polychlorinated dibenzo-p-dioxins and dibenzofurans in flue gas emissions from municipal solid waste incinerators in China

Polychlorinated dibenzo-p-dioxins and furalls(PCDD/Fs)emissions in flue gas from two types of municipal solid waste incinerators(MSWIs)most commonly used in China were investigated in this study.The selected incinerators include two grate-type MSWIs:MSWl-A(350 t/d)and MSWI-B(150 t/d),and two fluidized bed MSWIs:MSWI-C(400 t/d) and MSWI-D (400 t/d),which are all equipped with semi-dry lime scrubber and bag filter except MSWI-D equipped with cyclone and wet scrubber(WS)as air pollutant conffol device(APCD).Results indicated that the emission concentration and the international toxic equivalents(I-TEQs)of the PCDD/Fs from the stacks were in the range of 1.210～10.273 ng/Nm3 and 0.019～0.201 ngI-TEQ/Nm3,respectively.They were greatly lower than the emission regulation standard of PCDD/FS in China(1.0 ng I-TEQ/Nm3).However,only the PCDD/Fs emission Ievel from MSWI-C Was below 0.1 ng I-TEQ/Nm3.Although the homologue profiles were distinct,the contributions of the 2,3,7,8-subsituted congenem to the total I-TEQ were similar among all the investigated MSWIs.Two major 2,3,7,8-substituted congeners,2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDD,account for 47% and 9%(average values)of the total I-TEQ values,respectively.The correlation between PCDD/Fs levels and composition of flue gas Was also discussed.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in flue gas emissions from municipal solid waste incinerators in China

Polychlorinated dibenzo-p-dioxins and furans （PCDD/Fs） emissions in flue gas from two types of municipal solid waste incinerators （MSWIs） most commonly used in China were investigated in this study. The selected incinerators include two grate-type MSWIs： MSWI-A （350 t/d） and MSWI-B 050 t/d）, and two fluidized bed MSWIs： MSWI-C （400 t/d） and MSWI-D （400 t/d）, which are all equipped with semi-dry lime scrubber and bag filter except MSWI-D equipped with cyclone and wet scrubber （WS） as air pollutant control device （APCD）. Results indicated that the emission concentration and the international toxic equivalents （I-TEQs） of the PCDD/Fs from the stacks were in the range of 1.210-10.273 ng/Nm^3 and 0.019-0.201 ng I-TEQ/Nm^3, respectively. They were greatly lower than the emission regulation standard of PCDD/Fs in China （1.0 ng I-TEQ/Nm^3）. However, only the PCDD/Fs emission level from MSWI-C was below 0.1 ng I-TEQ/Nm^3. Although the homologue profiles were distinct, the contributions of the 2,3,7,8-subsituted congeners to the total I-TEQ were similar among all the investigated MSWIs. Two major 2,3,7,8-substituted congeners, 2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDD, account for 47% and 9% （average values） of the total I-TEQ values, respectively. The correlation between PCDD/Fs levels and composition of flue gas was also discussed.     

生活垃圾焚烧残灰中有毒成分的排放特性

目的：探索中国生活垃圾焚烧残灰中重金属、氯苯、多环芳烃等有毒成分的排放特性、排放水平及相互之间的关联特性,并认识其产生、排放与焚烧炉型、焚烧条件的关联,以探索控制其危害的有效方法。方法：1.对中国几个典型的生活垃圾焚烧炉现场采样,获得多个飞灰和底渣的样品;2.通过多种不同的检测手段和方法,分别检测残灰的基本物理化学特性、氯苯、多环芳烃和主要金属元素的浓度;3.结合焚烧炉型和焚烧特性等条件,分析各有毒成分的排放特性和相互之间的关联特性。结论：1.氯苯、多环芳烃和重金属受焚烧因素影响,在残灰中的排放特性各不相同,流化床焚烧炉能消除焚烧和原始垃圾的扰动,能控制氯苯在残灰中的排放,但多环芳烃排放控制不如炉排焚烧炉;2.残灰中主要的有机有毒成分为高氯代氯苯和2至4环等少环类多环芳烃;3.氯苯和多环芳烃在残灰中的含量可能因为不同的产生机理而表现出一定的负关联特点;4.残灰中的金属主要为铝和铁等轻金属,浓度远高于重金属元素,而无毒重金属（主要为Mn、Ni、As和Zn）浓度高于有毒重金属元素（Cu、Pb和Cr）,且不同金属表现出不同的对氯苯和多环芳烃的催化促进或抑制作用。     

Biodegradability of leachates from Chinese and German municipal solid waste

The quantitative and qualitative composition of Chinese municipal solid waste （MSW） differs significantly from German waste. The focus of this paper is on whether these differences also lead to dissimilar qualities of leachates during storage or landfilling. Leachates ingredients determine the appropriate treatment technique. MSW compositions of the two cities Guilin （China） and Essen （Germany）, each with approx. 600000 inhabitants, are used to simulate Chinese and German MSW types. A sequencing batch reactor （SBR） is used, combining aerobic and anaerobic reaction principles, to test the biodegradability of leachates. Leachates are tested for temperature, pH-value, redox potentials, and oxygen concentration. Chemical oxygen demand （COD） values are determined. Within 8 h, the biodegradation rates for both kinds of leachates are more than 90%. Due to the high organic content of Chinese waste, the degradation rate for Guilin MSW leachate is even higher, up to 97%. The effluent from SBR technique is suitable for direct discharge into bodies of water.     

Method for determining effective flame emissivity in a rotary kiln incinerator burning solid waste

Temperature is the most important parameter for the improvement of combustion efficiency and the control of pollutants. In order to obtain accurate flame temperatures in a rotary kiln incinerator using non-intrusive thermographic method, the effective flame emissivity was studied. A combined narrow- and wide-band model and Mie scattering method were used to calculate the radiative properties for gases and fly-ash particles under different combustion conditions. The effects of the air/waste ratio and fly-ash particles on the effective flame emissivity were discussed. The results of numerical calculations showed that the effective emissivity decreased from 0.90 to 0.80 when the air/waste ratio increased from 1.0 to 1.8, and the effect of the fly-ash particles was ignorable under the conditions discussed in this paper. Experimental measurement results indicated that the accuracy of the thermographic temperature measurements improved significantly if the setting of the flame emissivity was adjusted according to the air/waste ratio.     

杭州市机动车污染物排放的减排情景研究

研究目的：预测机动车保有量;根据机动车污染特征,预测机动车污染物排放量;评估不同管理措施下机动车污染物的削减效果。创新要点：综合不同管理措施,整合评价多种管理措施并行条件下,机动车污染物排放量的削减情况。研究方法：通过长期能源替代计划（LEAP）模型对机动车保有量进行预测,相关排放因子采用校正的能源替代（AER）模型进行估算。最后设计四个情景模式,评估不同情景的减排效果,并与基础情景进行对比。重要结论：1.至2015年杭州市机动车将增长60.7%。2.淘汰超标机动车和提高机动车污染排放标准能有效控制CO和VOCs,而对NOx和PM的总量削减效果不明显。3.采用多种控制手段,如淘汰劣化超标机动车、提高机动车排放标准、提供低硫代燃油及引进能源替换型机动车将大大减少机动车污染物的排放量。     

城市生活垃圾的土工性质及实验方法研究

通过垃圾土的室内成分试验,对杭州地区垃圾土的组成成分进行了分析研究,认为杭州地区垃圾土的主要组成成分为蔬菜、煤炭等生活垃圾.同时对垃圾土的土工性质进行了总结分析,得到了不同地区以及不同生活垃圾的容重、比重、含水量、孔隙比、渗透系数等的含量及分布规律.     

Removal of PCDDs/Fs from municipal solid waste incineration by entrained-flow adsorption technology

INTRODUCTION Polychlorinated dibenzodioxins and poly- chlorinated dibenzofurans (PCDDs/Fs) are some major toxic substances unintentionally produced mainly from municipal solid waste incineration (MSWI). Attention has been focused on the best way for controlling and regulating such emissions. Among flue gas treatment technologies for post combustion zone emission control (Buekens and Huang, 1998; McKay, 2002), activated carbon adsorption (ACA) and techniques involving physical adsorp…     

Changes in bacterial community of anthracene bioremediation in municipal solid waste composting soil

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in a municipal solid waste (MSW) composting site. Knowledge of changes in microbial structure is useful to identify particular PAH degraders. However, the microbial community in the MSW composting soil and its change associated with prolonged exposure to PAHs and subsequent biodegradation remain largely unknown. In this study, anthracene was selected as a model compound. The bacterial community structure was investigated using terminal restriction fragment length polymorphism (TRFLP) and 16S rRNA gene clone library analysis. The two bimolecular tools revealed a large shift of bacterial community structure after anthracene amendment and subsequent biodegradation. Genera Methylophilus, Mesorhizobium, and Terrimonas had potential links to anthracene biodegradation, suggesting a consortium playing an active role.     

Simulation of municipal solid waste gasification for syngas production in fixed bed reactors

This study proposes a model of syngas production from municipal solid waste （MSW） gasification with air in fixed bed reactors. The model （using Aspen plus simulator） is used to predict the results of MSW gasification and to provide some process fundamentals concerning syngas production from MSW gasification. The effects of gasification temperature, air equiva- lence ratio and moisture concentration on the composition of syngas, lower heating value （LHV） of syngas, heat conversion efficiency, and carbon conversion are discussed. The results indicate that higher temperature improves gasification, and higher air equivalence ratio increases the carbon conversion while decreasing syngas LHV. Heat conversion efficiency increases and reaches the maximum and then decreases with the increase of air equivalence ratio. Higher moisture concentration increases the carbon conversion and increases the heat conversion efficiency at lower ratios. Higher temperature and a lower equivalence ratio are favorable for obtaining a higher LHV of syngas at the same moisture concentration.     

浅析危险废物的管理与风险评价

危险废物具有毒害性、爆炸性、易燃性、腐蚀性、化学反应性、传染性、放射性等一种或几种以上的危害特性并以其特有的性质对环境产生污染,其危害的长期性和潜伏性对人类和环境构成很大威胁;应从减少废物的产生量、对有用资源回收利用、高温焚烧、稳定化和固化处理等方面着手加强对危险废的管理;危险废物管理的风险评价具体包括为运输过程风险评价、贮存过程风险评价、利用过程风险评价。     

Safety impact of piled municipal solid waste dumps in the Three Gorges Reservoir Region on water quality

The safety of water quality in the Three Gorges Reservoir(TGR)is very important.Protections and remediation of environment safety are very crucial for guaranteeing TGR environmental quality.When piled municipal solid waste(MSW) dumps are submerged without treatment,pollutants in the MSW will leach into the water and threaten the water safety of the reservoir.Based on the surveys of the amount,distribution and characteristics of piled MSW in the TGR area,this study focusing on the MSW dumps at the water leve...     

Field measurement of gas permeability of compacted loess used as an earthen final cover for a municipal solid waste landfill

The use of loess as an earthen final cover material is promising in northwest China which has an arid and semi-arid climate. A full-scale testing facility with an area 30 m long by 20 m wide was constructed at the Xi’an landfill of municipal solid wastes to investigate the performance of an inclined capillary barrier cover. The cover consisted of a compacted loess layer underlain by a gravel layer. The testing facility was well instrumented for a gas permeation test and recording of the soil conditions in terms of volumetric water content, pore gas pressure, and soil temperature. Tests were performed to measure the gas permeability of the compacted loess before and after the planting of vegetation on the cover. The field measurements demonstrate that the capillary break at the fine/coarse soil interface allows the upper compacted loess layer to retain more water, and conversely reduces its gas permeability, which is favorable for reducing landfill gas emissions. When the degree of saturation of the compacted loess was greater than 85%, the gas permeability decreased significantly with a further increment in volumetric water content. The growth of vegetation roots tended to fill the large pores in the upper loosely-compacted loess, resulting in a decrease in gas permeability of one order of magnitude. The influence of soil clods in the compacted loess on gas permeability can be one to two orders of magnitude due to an increase in pore size and a decrease in tortuosity.     

Technological feasibility of biodiesel production from bioaugmented hydrolysate of waste sludge in a municipal wastewater treatment plant

The hydrolysate of waste sludge was used as the feedstock of biodiesel production, and its technological feasibility was investigated. Waste sludge, collected from No.3 Municipal Wastewater Treatment Plant of Xi＇an, was hydrolyzed in two parallel reactors firstly. Yeast was added into one reactor for bioaugmentation, and the other reactor without yeast was used as a control. Then an acid-catalyzed in situ esterification process was carried out to convert the hydrolysate to biodiesel. The results of hydrolysis showed that the reactor bioaugmented with yeast could promote hydrolysis compared with the control one because of an obvious variance in total suspended solid （TSS）, volatile suspended solid （VSS） and soluble chemical oxygen demand （SCOD）. Furthermore, gas chromatography （GC） analysis exhibited that the total volatile fatty acid （VFA） was low in the hydrolysate of bioaugmentation reactor; however, its yield of the fatty acid methyl esters （FAMEs） by in situ esterification was obviously higher when compared with the control one. Therefore, it may be inferred that the hydrolysate of bioaugmentation was mainly inclined to longer-chain fatty acid rather than to VFA. Anyway, an FAMEs yield of 9.24% （wt%） from dried sludge was attained after the 12-d bioaugmentation hydrolysis and succedent esterification. This value was not only higher than that of the control one but also higher than that reported in previous literature. The above results illuminated that it was feasible to produce biodiesel from the bioaugmented hydrolysate of waste sludge.     

Time- and stress-dependent model for predicting moisture retention capacity of high-food-waste-content municipal solid waste: based on experimental evidence

Moisture retention capacity (MRC) is a key parameter for the prediction of leachate production of a municipal solid waste (MSW) pile. In this paper, five sets of laboratory tests were conducted in compression cells to characterize the variation of MRC with degradation time and overburden stress. Set A was conducted on the fresh high-food-waste-content (HFWC)-MSW under different degradation conditions and a sustained stress; Set B was on the fresh HFWC-MSW by alternation of degradation time and incremental stresses; Sets C, D, and E were on fresh HFWC-MSW, zero-food-waste-content (NFWC)-MSW, and decomposed MSW, respectively, being subjected to incremental stresses. The following findings were obtained from the test results: (1) The MRC of fresh HFWC-MSW decreased exponentially with degradation time under a sustained stress. The higher waste temperature or oxygen introduction would result in a faster declining of MRC. (2) The MRCs decreased linearly with a logarithmic increase of stress for all the MSW samples with different food waste contents. The MRC of HFWC-MSW was higher than that of NFWC-MSW under a given stress, and the decomposed MSW took the second place. (3) The variation of MRC appeared to be independent of stress path in terms of stress and degradation time. Based on the test results, the dependencies of the MRC of HFWC-MSW on degradation and stress were interpreted. Then, a time- and stress-dependent model was proposed for predicting the MRC of HFWC-MSW. The model was relatively simple and convenient for design purposes, and was verified by the measured data of leachate production at the pretreatment container of Laogang Incineration Plant. Finally, the model was developed to evaluate the dewatering effect of the HFWC-MSW pile. The strategy of combining the degradationenhancing measures with stress-increasing measures is recommended in a rapid dewatering project.     

Evaluating risk for targeted violence in schools: Comparing risk assessment,threat assessment,and other approaches

In the wake of recent school shootings, fear over violence in schools has prompted increased requests for psychologists, educators, and law enforcement professionals to assist in preventing future school violence incidents. We attempt to lay a foundation for developing effective assessment and prevention approaches by first distinguishing planned school‐based attacks from other forms of school and youth violence. We then review the three assessment approaches that have been advocated and used in some jurisdictions (profiling, guided professional judgment, automated decision‐making) and demonstrate why they are inappropriate—and potentially harmful—in preventing planned school‐based attacks. We then describe the contours of the threat assessment approach, developed by the U.S. Secret Service to prevent assassinations, and examine its utility for responding to communications or behaviors of concern that students may present in school settings. © 2001 John Wiley & Sons, Inc.     

Epidemiological and clinical characteristics of 266 cases of intracerebral hemorrhage in Hangzhou, China

Ethnicity and socioeconomic factors can influence disease susceptibility, clinical presentation, and outcome. We investigated the clinical characteristics (age, sex, seasonal variation, lesion site, symptoms, complications, prognosis, and sequelae) and risk factors for intracerebral hemorrhage (ICH) in 266 cases treated at our hospital in Hangzhou City, China, from January 2011 to December 2011. Risk of ICH increased dramatically with age; only 4.3% of cases were <30 years old, while 44.4% were >60 years of age. Men outnumbered women by 2:1 (67.3% vs. 32.7%). Single hemorrhage was most often located in the cerebral lobes (37.2% of cases), basal ganglia (34.2%), thalamus (8.3%), cerebellum (6.8%), ventricle (1.5%), and brainstem (1.1%), while 10.9% of cases exhibited hemorrhages at multiple sites. Hypertension was also a major risk factor for ICH, as 47% of all patients were hypertensive and the percentage increased with age. In hypertensive patients, the most common hemorrhage site was the basal ganglia and ICH was often associated with thrombopenia. In patients with leukemia (all forms), most hemorrhages were lobar. Warfarin- and encephalic operation-associated ICHs were all lobar. Headache was the major symptom of occipital, temporal, and frontal lobe hemorrhage. Dizziness, nausea, and vomiting were the major symptoms of cerebellum hemorrhage. Limb dysfunction was the major symptom of thalamic and basal ganglia hemorrhage. Disturbed level of consciousness was the major symptom in multisite, ventricular, parietal lobe, and brainstem hemorrhage. Hyperspasmia occurred most often in lobar hemorrhage and blurred vision in occipital lobe hemorrhage. Hospital mortality was 24.4% (n=65) with a mean delay from presentation to death of (10.5±18.5) d. The majority of fatalities were cerebral hernia cases (58.5%) and these patients also had the shortest time to death [(2.9±3.5) d]. Mortality was 100% in brainstem ICH and hemorrhagic conversion of cerebral infarct. Thrombopenia-associated ICH also had a high mortality rate (81.0%), while patients with cerebrovascular malformations and cerebral aneurysms demonstrated a much better prognosis (46.2% recovery).     

Child sexual abuse and its relationship with health risk behaviors among rural children and adolescents in Hunan, China

Objective

The current study was designed to explore the prevalence of child sexual abuse (CSA) and its association with health risk behaviors (i.e., smoking, alcohol use, binge drinking, suicidal ideation, and suicide attempt) among rural children and adolescents in China.

Methods

A sample of 683 rural children and adolescents (8 to 18 years of age) completed an anonymous questionnaire which assessed experiences of CSA and 5 health risk behaviors. Data on several potential confounding factors were also collected.

Results

A total of 123 (18%) respondents reported experiencing at least 1 kind of CSA before 16 years of age, with more boys reporting CSA than girls (21.5% vs. 14.2%). In addition, attending non-boarding schools, lower levels of self-esteem, and higher levels of perceived peer pressure for engagement in health risk behaviors were associated with higher rates of CSA. Multivariate logistic regression analyses revealed that CSA experience was significantly associated with cigarette smoking (aOR = 2.14), binge drinking (aOR = 2.68), suicidal ideation (aOR = 1.69), and suicide attempt (aOR = 2.69) after controlling for several demographic and psychological factors.

Conclusion

More attention should be paid to the issues of CSA among rural children and adolescents in China. Effective CSA prevention intervention needs to address the vulnerabilities of the population, increase children's and parents’ awareness of CSA and ability of self-protection.     

Effect of relative humidity on non-refractory submicron aerosol evolution during summertime in Hangzhou,China

Relative humidity (RH) has a significant and complex effect on aerosols because of the aqueous phase process and gas-particle partition. The mass concentration and size distribution of organic aerosols, sulfate, nitrate, ammonium, and chloride were measured using high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS). These measurements were recorded from Aug. 5 to Sept. 23, 2016 in Binjiang District, Hangzhou, China, during which period more than 78% of the readings showed an RH over 60%, while the average temperature was 26 °C. Correlation analysis was applied to inorganic aerosol measurements while positive matrix factorization (PMF) was applied for source apportionment of organic aerosols (OA). The pattern of fixation of ammonium in aerosols changed as the RH increased, suggesting that RH enhances nitrate participation in particles, while sulfate is scavenged by droplets. All species of non-refractory submicron particles (NR-PM₁) showed an increase in their peak size as the RH increased. Primary OA (POA) continuously accumulated as the RH increased. When RH<60%, oxygenated OA (OOA) increased with increasing RH because of oxidation; semi-volatile OOA (SV-OOA) had a higher mass concentration during the daytime than at nighttime, indicating that the aqueous phase process and photochemistry synergistically affect the formation of oxygenated SV-OOA. When RH>60%, there was a relatively slow decrease in OOA, dominated by the wet removal effect rather than oxidation. The degree of oxidation of OA decreased as RH increased; this can be explained by most of the OOA with higher hygroscopicity being removed as droplets.     

A nationwide epidemiologic modeling study of LD: risk, protection, and unintended impact

Through multiple logistic regression modeling, this article explores the relative importance of risk and protective factors associated with learning disabilities (LD). A representative national sample of 6- to 17-year-old students (N = 1,268) was drawn by random stratification and classified by the presence versus absence of LD in reading, spelling, and mathematics according to ability-achievement discrepancies or low achievement levels. The dichotomous classifications were regressed on sets of explanatory variables indicating potential biological, social-environmental, and cognitive factors, problem behavior, and classroom learning behavior. Modeling revealed patterns of high risk for male students and students evincing verbal and nonverbal ability problems and processing speed problems. It was shown that, absent controls for cognitive abilities (such as provided by the ability-achievement discrepancy definition), definitions keyed to low achievement will substantially overidentify ethnic minority and disadvantaged students and will be confounded by significantly higher proportions of students who display oppositional and aggressive behavior problems. Alternatively, good learning behaviors uniformly provide substantial reduction in the risk for LD.