Effects of Using Municipal Solid Waste Incineration Tailings as Lightweight Aggregate on the Mechanical Properties of Specified Density Concrete

Municipal solid waste incineration tailings were used as lightweight aggregate(MSWIT-LA)in the preparation of specified density concrete to study the effects on compressive strength,axial compressive strength,flexural strength,microhardness,total number of pores,pore area,and pore spacing.The results showed that the internal curing and morphological effects induced by an appropriate quantity of MSWIT-LA improved the compressive response of specified density concrete specimens,whereas an excessive quantity of MSWIT-LA significantly reduced their mechanical properties.An analysis of pore structure indicated that the addition of MSWIT-LA increased the total quantity of pores and promoted cement hydration,resulting in a denser microstructure than that of ordinary concrete.The results of a principal component analysis showed that the mechanical response of specified density concrete prepared with 25%MSWIT-LA was superior to that of an equivalent ordinary concrete.It was therefore concluded that MSWIT-LA can be feasibly applied to achieve excellent specified density concrete properties while utilising municipal solid waste incineration tailings to protect the environment and alleviate shortages of sand and gravel resources.

Model Prediction and Optimal Control of Gas Oxygen Content for A Municipal Solid Waste Incineration Process

In the municipal solid waste incineration process,it is difficult to effectively control the gas oxygen content by setting the air flow according to artificial experience.To address this problem,this paper proposes an optimization control method of gas oxygen content based on model predictive control.First,a stochastic configuration network is utilized to establish a prediction model of gas oxygen content.Second,an improved differential evolution algorithm that is based on parameter adaptive and t-distribution strategy is employed to address the set value of air flow.Finally,model predictive control is combined with the event triggering strategy to reduce the amount of computation and the controller's frequent actions.The experimental results show that the optimization control method proposed in this paper obtains a smaller degree of fluctuation in the air flow set value,which can ensure the tracking control performance of the gas oxygen content while reducing the amount of calculation.

基于Aspen Plus的MSW气化熔融工艺全流程模拟研究

城市固体废物(MSW)气化熔融工艺能够减少二噁英的生成和熔融固化重金属,是一种清洁高效的固体废物处理方式。已有研究多针对MSW的热解特性以及污染物的生成与排放,而对气化熔融工艺系统模块之间的影响和各反应器间物质流、能量流的联动变化过程研究不足。利用Aspen Plus模拟平台,基于吉布斯自由能最小化原理,对MSW气化熔融工艺进行了全流程模拟研究,分析了垃圾干燥温度、垃圾含水率、气化温度、气化介质以及灰熔点对工艺流程节点参数、物质流和能量流的影响,并提出了优化的工艺流程和运行参数。结果表明:在垃圾热解模拟时,垃圾含水率为9%,通过烟气循环能达到能量自给;在相同条件下,以水蒸气作为气化介质的气化效率最高,且在气化温度为850℃,水蒸气当量比为50%时,达到最佳工艺效果;当气化后产生的焦炭在熔融炉内燃烧刚满足灰熔点温度时,灰熔点的升高使气化剂比例、气化气有效气体摩尔流量和碳转化率不断降低。不同工况下的物质流、能量流的变化对实际工程具有指导意义。

Prediction of NO_(x)concentration using modular long short-term memory neural network for municipal solid waste incineration

Air pollution control poses a major problem in the implementation of municipal solid waste incineration(MSWI).Accurate prediction of nitrogen oxides(NO_(x))concentration plays an important role in efficient NO_(x)emission controlling.In this study,a modular long short-term memory(M-LSTM)network is developed to design an efficient prediction model for NO_(x)concentration.First,the fuzzy C means(FCM)algorithm is utilized to divide the task into several sub-tasks,aiming to realize the divide-and-conquer ability for complex task.Second,long short-term memory(LSTM)neural networks are applied to tackle corresponding sub-tasks,which can improve the prediction accuracy of the sub-networks.Third,a cooperative decision strategy is designed to guarantee the generalization performance during the testing or application stage.Finally,after being evaluated by a benchmark simulation,the proposed method is applied to a real MSWI process.And the experimental results demonstrate the considerable prediction ability of the M-LSTM network.

Mechanical and environmental properties of geopolymer-stabilized domestic waste incineration slag in an asphalt pavement base

Domestic waste incineration slag(WIS)includes fly ash and slag.Fly ash is classified as hazardous waste because it contains heavy metals.Most of slag are directly stacked or landfilled due to problems such as large output and low utilization rate.Harmless treatment is imminent.If WIS is used effectively in the road engineering,which can realize the high-quality and high-efficiency recycling of WIS,and it is of great significance to save resources and protect the environment.This study applies a geopolymer prepared from WIS fly ash as a stabilizing agent in WIS blending macadam for use as a pavement base mixture,and reports the mechanical properties(unconfined compressive strength,splitting strength,and resilience modulus)of the geopolymer-stabilized WIS blending macadam(GeoWIS).The leaching concentrations of harmful heavy metals of GeoWIS soaked in water were also investigated.Finally,the strength formation and heavy metal stability mechanisms were explored.The unconfined compressive strength,splitting strength,and compressive resilient modulus of GeoWIS all increased with increasing geopolymer content and decreasing WIS content.The strength of GeoWIS was derived from its geopolymerization and hydration products(C-S-H gel,N-A-S-H gel,and AFt).When the geopolymer content reached 12%–14%,the GeoWIS without natural macadam met the strength criterion of the asphalt pavement base.Through physical adsorption and chemical bonding,the geopolymer significantly reduced the leaching of harmful heavy metals.In GeoWIS with 50%WIS and stabilized with 10%geopolymer,the Cr,Ni,Cd,and Pb concentrations met the grade III groundwater standard.Concentrations of heavy metals leached from GeoWIS are low and exert little impact on environment.

Hydration Kinetics of Municipal Solid Wastes Incineration(MSWI) Fly Ash-Cement

Hydration heat behavior and kinetics of blended cement containing up to 20% MSWI fly ash were investigated based on its hydration heat evolution rate measured by isothermal calorimeter. Kinetics parameters, N and K, and hydration degree, Ca(OH)2 content, were also calculated and analyzed. According to the experimental results, the induction period was elongated, the second heat evolution peak was in advance, and the third hydration heat peak could be detected due to MSWI fly ash pozzolanic reaction. The hydration reaction rate was controlled by nucleation kinetics in the acceleration period and then by diffusion in the decay period, but in the deceleration period, the hydration experienced a dual controlling reaction of autocatalytic chemical reaction and diffusion. The hydration rate of blended cement was faster. Ca(OH)2 content increased before 14 days.

Analysis of the Relationship between Mechanical Properties and Pore Structure of MSW Incineration Bottom Ash Fine Aggregate Concrete after Freeze-Thaw Cycles Based on the Gray Theory

The destruction of concrete building materials in severely cold regions of the north is more severely affected by freeze-thaw cycles,and the relationship between the mechanical properties and pore structure of concrete with fine aggregate from municipal solid waste(MSW)incineration bottom ash after freeze-thaw cycles is analyzed under the degree of freeze-thaw hazard variation.In this paper,the gray correlation method is used to calculate the correlation between the relative dynamic elastic modulus,compressive strength,and microscopic porosity parameters to speculate on the most important factors affecting their changes.The GM(1,1)model was established based on the compressive strength of the waste incineration ash aggregate concrete,the relative error between the simulated and actual values in the model was less than 5%,and the accuracy of the model was level 1,indicating that the GM(1,1)model can well reflect the change in the compressive strength of the MSW incineration bottom ash aggregate concrete during freeze-thaw cycles.Using the gray correlation method,the correlation between the relative dynamic elastic modulus,compressive strength,air content,specific surface area,pore spacing coefficient,and pore average chord length was calculated,and the pore spacing coefficient and pore average chord length were determined to be highly correlated with each other.This determination can help analyze and infer the deterioration mechanism of concrete subject to freeze-thaw cycles.These results can provide a theoretical basis for guiding the engineering practice of concrete with fine aggregates of household bottom ash in the northern cold region.

水泥窑协同处置MSW环境负荷与性能耦合评价

基于中国某水泥厂2022~2023年生产数据及近3年国家/行业统计数据进行生命周期评价,核算水泥窑协同处置城市生活垃圾(MSW)生产不同品种水泥的环境负荷;联合数据质量指标评估和蒙特卡洛模拟来综合评估最终结果的不确定度.与常规工艺相比,水泥窑协同处置工艺生产每吨熟料的综合环境负荷降幅为7.82%;4种水泥中,P·O 52.5水泥的综合环境负荷最大,但其单位强度的环境负荷相对较小.综合考虑,采用水泥窑协同处置工艺生产P·C 42.5水泥与采用常规工艺生产P·O 42.5水泥相比,其综合环境负荷降幅为16.87%.

基于混合数据增强的MSWI过程燃烧状态识别

国内城市固废焚烧(Municipal solid waste incineration, MSWI)过程通常依靠运行专家观察炉内火焰识别燃烧状态后再结合自身经验修正控制策略以维持稳定燃烧,存在智能化水平低、识别结果具有主观性与随意性等问题.由于MSWI过程的火焰图像具有强污染、多噪声等特性,并且存在异常工况数据较为稀缺等问题,导致传统目标识别方法难以适用.对此,提出一种基于混合数据增强的MSWI过程燃烧状态识别方法.首先,结合领域专家经验与焚烧炉排结构对燃烧状态进行标定;接着,设计由粗调和精调两级组成的深度卷积生成对抗网络(Deep convolutional generative adversarial network, DCGAN)以获取多工况火焰图像;然后,采用弗雷歇距离(Fréchet inception distance, FID)对生成式样本进行自适应选择;最后,通过非生成式数据增强对样本进行再次扩充,获得混合增强数据构建卷积神经网络以识别燃烧状态.基于某MSWI电厂实际运行数据实验,表明该方法有效地提高了识别网络的泛化性与鲁棒性,具有良好的识别精度.

Microstructural analysis of marl stabilized with municipal solid waste and nano-MgO

Municipal solid waste(MSW)is accumulating over elapsed time across the world,and it is observed in many projects associated with weak soils,such as marl.Therefore,effective solutions to the environmental problem are essential.Conventional techniques for stabilizing marl generally use substances such as lime and cement,which could exacerbate pollution.For this,some new stabilizers,e.g.nano-MgO,are used.There are large quantities of marls and MSW in Shiraz City,Iran.The present study aims to evaluate the feasibility of using nano-MgO as a green low-carbon binder to remove MSW from the environment and make construction projects more cost-effective.Consolidated drained shear tests were conducted to evaluate the mechanical behaviors of the nano-MgO treated marl specimens at high normal stresses.The marl specimens containing MSW percentages of 15%,25%,35%,and 45%and nano-MgO percentages of 0.25%,0.5%,0.75%,and 1%,were used.It is found that the marl containing 15%and 25%MSW and 0.5%nano-MgO at 28-d curing can perform cation exchange and form new cementitious products.The soils with merely MSW show good performance due to the removal of the kaolinite and the formation of brucite.However,the soil with 25%MSW and 0.5%nano-MgO shows the same strength enhancement as the specimen with the optimal nano-MgO(0.75%)through the formation of dolomite,with a 20.59%increase in strain energy(SE).

Application of Multivariate Reinforcement Learning Engine in Optimizing the Power Generation Process of Domestic Waste Incineration

Garbage incineration is an ideal method for the harmless and resource-oriented treatment of urban domestic waste.However,current domestic waste incineration power plants often face challenges related to maintaining consistent steam production and high operational costs.This article capitalizes on the technical advantages of big data artificial intelligence,optimizing the power generation process of domestic waste incineration as the entry point,and adopts four main engine modules of Alibaba Cloud reinforcement learning algorithm engine,operating parameter prediction engine,anomaly recognition engine,and video visual recognition algorithm engine.The reinforcement learning algorithm extracts the operational parameters of each incinerator to obtain a control benchmark.Through the operating parameter prediction algorithm,prediction models for drum pressure,primary steam flow,NOx,SO2,and HCl are constructed to achieve short-term prediction of operational parameters,ultimately improving control performance.The anomaly recognition algorithm develops a thickness identification model for the material layer in the drying section,allowing for rapid and effective assessment of feed material thickness to ensure uniformity control.Meanwhile,the visual recognition algorithm identifies flame images and assesses the combustion status and location of the combustion fire line within the furnace.This real-time understanding of furnace flame combustion conditions guides adjustments to the grate and air volume.Integrating AI technology into the waste incineration sector empowers the environmental protection industry with the potential to leverage big data.This development holds practical significance in optimizing the harmless and resource-oriented treatment of urban domestic waste,reducing operational costs,and increasing efficiency.

Levels of Polycyclic Aromatic Hydrocarbons (PAHs) in Healthcare Waste Incinerators’ Bottom Ash from Five County Hospitals in Kenya

Health-care waste contains potentially harmful microorganisms and compounds which can infect and affect hospital patients, healthcare workers, the general public and environment. Therefore, management of health care waste requires safe handling, treatment and disposal procedures. While incineration reduces the volume and quantity of waste for final disposal, it leads to the production of fly and bottom ashes laden with toxic incomplete combustion products such as Polycyclic Aromatic Hydrocarbons (PAHs), dioxins, furans and heavy metals. This exposes workers who handle and dispose the bottom ashes, hospital patients, the general public and environment. The goal of this study was to determine the total and individual levels of 16 most prevalent and toxic PAHs. Bottom ash samples were collected from incinerators in five county hospitals in Kenya, namely;Moi-Voi, Narok, Kitale, Makindu and Isiolo. Bottom ash samples were collected over a period of six months from the five hospitals. The samples were then sieved, homogenised and stored at 4°C in amber coloured glass containers. The PAHs were extracted using 30 ml of a hexane-acetone solvent (1:1) mixture by ultrasonication at room temperature (23°C) for 45 minutes. The PAHs were then analyzed with a GC-MS spectrophotometer model (Shimadzu GCMS-QP2010 SE) connected to a computer work station was used for the PAHs analysis. The GC-MS was equipped with an SGE BPX5 GC capillary column (30 m × 0.25 mm × 0.25 μm) for the separation of compounds. Helium was used as the carrier gas at a flow rate of 15.5 ml/minute and 14.5 psi. 1 μl of the sample was injected at 280°C, split mode (10:1). The oven programming was set for a total runtime of 40 minutes, which included: 100°C (2-minute hold);10°C /min rise to 200°C;7°C /min rise to 249°C;3°C /min rise to 300°C (2-minute hold). The interface temperature was set at 290°C. Analysis was done in Selected Ion Monitoring (SIM) mode and the peak areas of each of the PAHs were collected from the chromatograph and used for quantification of the 16 PAHs listed by the U.S. Environmental Protection Agency (EPA) which included, BaA (benz[a]anthracene: 4 rings), BaP (benzo[a]pyrene: 5 rings), BbF (benzo [b]fluoranthene: 5 rings), BkF (benzo[k]fluoranthene: 5 rings), Chr (chrysene: 4 rings), DbA (dibenz[a,h]anthracene: 5 rings), InP (indeno[1,2,3 - cd] pyrene: 6 rings) and Acp (acenaphthene: 3 rings), Acpy (acenaphthylene: 3 rings), Ant (anthracene: 3 rings), BghiP (benzo[g,h,i]perylene: 6 rings), Flu (fluorene: 3 rings), FluA (fluoranthene: 4 rings), Nap (naphthalene: 2 rings), PhA (phenanthrene: 3 rings) and Pyr (pyrene: 4 rings). Ion source-interface temperature was set at 200°C - 250°C. Internal standards from Sigma Aldrich were used in the analysis and the acquired mass spectra data were then matched against the NIST 2014 library [1] [2]. The mean PAHs concentration in the bottom ashes of each hospital varied broadly from 0.001 mg/kg to 0.4845 mg/kg, and the mean total concentration levels of individual PAHs ranged from 0.0072 mg/kg to 1.171 mg/kg. Low molecular weight PAHs (Phenanthrene, Naphthalene and Fluorene) were predominant in all the hospital wastes whereas Kitale and Narok presented the lowest PAHs concentrations and the lowest number of individual PAHs. Moi/Voi recorded the highest total PAHs concentration at 1.3129 ± 0.0023 mg/kg from a total of 11 PAHs being detected from the bottom ash samples. Narok had only three PAHs being detected at very low concentrations of 0.0041 ± 0.00 mg/kg, 0.0076 ± 0.00 mg/kg and 0.012 ± 0.00 mg/kg for phenanthrene, anthracene and chrysene respectively. This study presents hospital incinerator bottom ash as containing detectable levels of both carcinogenic and non-carcinogenic PAHs. Continued unprotected exposure of hospital workers (waste handlers) to the bottom ash PAHs could be hazardous to their health because of their cumulative effect. Preventive measures e.g. the use of Personal protective equipment (PPE) should be prioritised to minimise direct contact with the bottom ash. The study recommends an upgrade on incinerator technology for efficient combustion processes thus for better pollution control.

Engineering and Physical Bases of Development and Creation of Plasmochemical Reactors for Mobile Facilities for Medical Waste Disposal

This paper presents the results of the development and creation of plasma-chemical reactors for mobile and stationary installations for the destruction and disposal of solid, liquid, gaseous and mixed medical waste based on the domestic plasma generator PUN-1, with air as the plasma-forming gas. The design and principle of operation of plasma-chemical reactors installed on mobile experimental and industrial plants “Plazmon-1,2,3”, as well as the main features of the plasma waste disposal process are described.

Leaching behavior of heavy metals with hydrochloric acid fromfly ash generated in municipal waste incineration plants

The extraction behavior of heavy metals from municipal waste incineration （MWI） fly ash was investigated systematically. The extraction process includes two steps, namely, fly ash was firstly washed with water, and then subjected to hydrochloric acid leaching. The main parameters for water washing process were tested, and under the optimal conditions, about 86% Na, 70% K and 12% Ca were removed from fly ash, respectively. Hydrochloric acid was used for the extraction of valuable elements from the water-washed fly ash, and the optimal extraction was achieved for each heavy metal as follows： 86% for Pb, 98% for Zn, 82% for Fe, 96% for Cd, 62% for Cu, 80% for Al, respectively. And the main compositions of the finally obtained solid residue are Ca2PbO4, CaSi2Os, PbsSiO7, Ca3A12Si3012 and SiO2.

Investigation of heavy metal partitioning influenced by flue gas moisture and chlorine content during waste incineration

The impact of moisture on the partitioning of the heavy metals including Pb,Zn,Cu and Cd in municipal solid waste （MSW） was studied in a laboratory tubular furnace.A thermodynamic investigation using CHEMKIN software was performed to compare the experimental results.Simulated waste,representative of typical MSW with and without chlorine compounds,was burned at the background temperature of 700 and 950°C,respectively.In the absence of chlorine,the moisture content has no evident effect on the volatility of Pb,Zn and Cu at either 700 or 950°C,however,as flue gas moisture increasing the Cd distribution in the bottom ash increased at 700°C and reduced at 950°C,respectively.In the presence of chlorine,the flue gas moisture reduced the volatility of Pb,Zn and Cu due to the transformation of the more volatile metal chlorides into less volatile metal oxides,and the reduction became significant as chlorine content increase.For Cd,the chlorine promotes its volatility through the formation of more volatile CdCl 2.As a result,the increased moisture content increases the Pb,Zn,Cu and Cd concentrations in the bottom ash,which limits the utilization of the bottom ash as a construction material.Therefore,in order to accumulate heavy metals into the fly ash,MSW should be dried before incineration.

Effect of quarry dust addition on the performance of controlled low-strength material made from industrial waste incineration bottom ash

The performance of industrial waste incineration bottom ash in controlled low-strength material （CLSM） was investigated in this paper, as the quarry dust was added. CLSM mixtures were made from the industrial waste incineration bottom ash, quarry dust, and cement. Tests for fresh density, bleeding, compressive strength, shear strength, hydraulic conductivity, and excavatability were carried out. The com- pressive strength ranges from 60 kPa to 6790 kPa, the friction angle varies from 5°to 19°, and the cohesion is from 4 to 604 kPa. Most of the mixtures are found to be non-excavatable. It is indicated that the quarry dust addition increases the compressive strength and shear parame- ters, decreases bleeding, and increases the removability modulus.

Volatilization of heavy metals during incineration of municipal solid wastes

Incineration experiments with MSW, which had been impregnated with heavy metals, were presented to obtain information on the volatilization behavior of the elements cadmium(Cd), lead(Pb), and zinc(Zn) under different conditions. Experiments were carried out in a bubbling fluid bed system connected to a customized inductively coupled plasma optical emission spectroscopy(ICP-OES) for analyzing metals in the flue gas. The results indicated that the combustion temperature, the gas atmosphere, and the chlorine content in the flue gas could affect the volatilization behavior of heavy metals. In the fluidized bed combustion, a large surface area was provided by the bed sand particles, and they may act as absorbents for the gaseous ash-forming compound. Comparer with the metals Cd and Pb, the vaporization of Zn was low. The formation of stable compounds such as ZnO·Al 2O 3 could greatly decrease the metals volatilization. The presence of chlorine would enhance the volatilization of heavy metals by increasing the formation of metal chlorides. However, when the oxygen content was high, the chlorinating reaction was kinetically hindered, which heavy metals release would be delayed.

Effect of Moisture on Partitioning of Heavy Metals in Incineration of Municipal Solid Waste

The effect of moisture in municipal solid waste (MSW) on partitioning of lead (Pb), zinc (Zn), copper (Cu) and cadmium (Cd) was studied in a laboratory tubular furnace by using simulated MSW. The moisture in MSW influences heavy metals in following ways, to increase the moisture in flue gas and decrease the combustion temperature, to prolong the combustion time, and to prolong the releasing time of volatiles with the furnace temperature decreased by increasing the moisture. The volatilization of Pb, Zn and Cd was enhanced by increasing the moisture in MSW because of the prolonged combustion time. For Pb and Zn, the combustion time was important at higher temperature, while for Cd, it was important at low temperature. The moisture content showed slight effect on Cu partitioning. When extra chlorine was added to MSW, such as 1%PVC + 0.5%NaCl, the volatilization of Pb, Zn and Cu was enhanced by increasing the moisture because water evaporation reduced the temperature and increased devolatilization time. At higher temperature, NaCl tends to decompose and generates more free chlorine, producing more metal chlorides. Since Cd is a strong volatile heavy metal in MSW, the effect of moisture content on its volatilization is less than that of Pb, Zn or Cu during the MSW incineration.

Glass-ceramics made from arc-melting slag of waste incineration fly ash

Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis （DTA）, X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Results show that main crystalline phase of the glass-ceramics fi＇om grate fly ash is wollastonite （CaSiO3） with small amount of diopside （Ca（Mg,Al）（Si,Al）206）, and that from fluidized bed fly ash is diopside （Ca（Mg,Al）（Si,Al）206）. It is found that the glass-ceramics sintered at 850 ℃and 1 000℃ from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles.

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of Such crystals as SiO2, CaSO4 and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.