Effect of inoculation dosing on the composting of source‐selected organic fraction of municipal solid wastes

The effects of a commercial inoculum (MicroGest 10X, Brookside Agra L.C.) on the field‐scale composting of the source‐selected organic fraction of municipal solid wastes (OFMSW) have been studied by following routine parameters of the composting process (temperature, oxygen content and moisture) and biologically‐related tests such as the respirometric index and the maturity grade. The inoculum was added to composting piles of OFMSW at different levels: control (no added inoculum), treatment A (10⁵ CFU g^?1 of OFMSW), treatment B (10⁶ CFU g^?1 of OFMSW) and treatment C (10⁷ CFU g^?1 of OFMSW). The inoculum selected produced a significant acceleration of the composting process with high levels of biological activity in the thermophilic phase. In terms of the acceleration of composting and economy the optimal treatment was B, which produced a reduction of approximately half of the total composting time. Treatment C did not improve significantly the results obtained with treatment B, whereas treatment A has little effect on the composting of OFMSW when compared with the control experiment. Respirometric index (determined at 55 °C) and maturity grade appeared to be the most reliable tests to follow the biological activity of the composting of OFMSW. On the other hand, routine parameters such as temperature, oxygen content and moisture showed no significant differences among the different inoculation levels tested in the composting process. Copyright © 2005 Society of Chemical Industry     

Effects of anaerobic composting on tetracycline degradation in swine manure

Oxytetracycline (OTC) and tetracycline (TC) are the most common TC antibiotics used in human and veterinary medicine.Residual amounts of these antibiotics in manure pose a potential threat to public and ecological health as a result of the potential for them to be released to the environment following land application of manure from animals treated with antibiotics.We investigated the degradation of OTC and TC during anaerobic composting.We tested the effects of temperature and antibiotic concentration on degradation rates in a control and in manure spiked with TCs.We examined changes in pH,biological degradation material (BDM),and moisture corresponding with antibiotic degradation of TCs in the swine manure.Results showed that the OTC and TC concentrations decreased by between 68.54％ and 95.50％ in all nine treatments following 14 days of anaerobic composting,and the highest removal efficiencies were observed at an incubation temperature of 55 ℃ and initial concentrations of 10.36 pg.g-1,and 5.96 μg.g 1 of OTC and TC respectively,which were degraded by 95.50％,and 90.06％.During composting at 55 ℃ and at added concentrations of 5 μg·g-1,OTC decreased rapidly,and the time required for 50％ and 90％ degradation was 4.1 and 9.8 days,respectively;for TC these values were 4A and 14.0 days,respectively.Removal efficiencies for all TCs correlated well with moisture content of the manure.These results show that composting may be a practical and useful means to reduce concentrations of OTC and TC in swine manure prior to its land application.     

Influence of uric acid amendment on the in‐vessel process of composting composite food waste

BACKGROUND: The food waste produced in small cities, rural areas and small communities often coexists with agroindustrial waste, such as livestock and poultry manure, which include high levels of uric acid (UA). This study investigated the influence of UA on the composting of food waste in an in‐vessel system. RESULTS: Results showed that the performance of food waste composting was significantly different in systems with UA amendment and without UA amendment. Treatment with UA addition was the first to reach the thermophilic phase. More intensive mass reduction took place in the UA‐amended treatments at an early stage. The variations of pH and O₂ uptake were also correlated with the added UA. A decreasing trend in C/N ratio and a general increasing trend for NH$_{4}^{+}$ ‐N concentration were observed when UA was added. CONCLUSIONS: The overall effect of UA can be assumed to be the sum of a large number of individual events with different mechanisms. Appropriate strategies could be applied to adjust the composting process, mediating both positive and negative effects of the coexistence of food waste and UA as well as manure. The results from this study may have important implications for composting technologies used to treat food waste. Copyright © 2012 Society of Chemical Industry     

基于生物炭强化有机固废好氧堆肥资源化的研究进展

好氧堆肥是实现有机固体废物无害化、稳定化以及资源化的有效手段。近年来,生物炭作为一种堆肥调理剂在优化堆肥环境参数、加速堆肥进程与提升堆肥品质等方面显示出广阔的前景。生物炭具有丰富的多孔结构和巨大的比表面积以及高效的持水能力、阳离子交换能力和吸附能力,这些性质对促进堆肥进程有巨大优势,比如强化微生物群落活性、促进有机物降解与腐殖质形成、减少臭气和温室气体排放、降低重金属和抗生素以及其他污染物的生物有效性等。本文综述了生物炭在不同类型有机废弃物好氧堆肥过程中的作用,总结了基于生物炭的强化手段在堆肥中的应用,并提出了生物炭未来研究的发展方向,旨在从功能材料方面优化好氧堆肥工艺,并为生物炭在好氧堆肥中的应用提供理论依据和数据支撑。     

ATP测定在活性污泥法中的应用研究

本文介绍ＡＴＰ测定原理及测定方法，通过试验研究阐明了ＡＴＰ测定在活性污泥法中的应用情况。     

城市垃圾焚烧发电污染物处理技术

城市垃圾焚烧发电以其具有明显的减量化、无菌化、资源化等优点,近年来得到了较广泛的应用。然而,垃圾焚烧后产生的酸性气体、二噁英、灰渣及废水等,如果处理处置不慎就会对环境产生二次污染。文章概述了酸性气体、二噁英、灰渣及废水等垃圾焚烧二次污染物的形成机理,并详细介绍了控制垃圾焚烧所产生二次污染物的方法与措施。     

Development of a mathematical model for the simulation of the biodegradation of organic substrates in a high-solids anaerobic digestion process

A kinetic model is developed to simulate the biodegradation of the organic fraction of municipal solid waste in a high-solids complete-mix continuous-flow anaerobic digestion process. A mass balance correction factor (f) is used to account for (i) the water that is incorporated into the production of biogas, and (ii) the water vapor present in the biogas. With the inclusion of the factor f, expressions are developed to determine the substrate removal efficiency based on first-order and Monod kinetic models. Simulations using first-order and Monod kinetic models are carried out to illustrate the importance of the f factor on the substrate mass removal and microorganism concentration in the high-solids anaerobic digestion process. The effect of the value of f on kinetic constants, and the error involved in considering the high-solids process as a low-solids process are discussed. Finally, experimental results from a pilot-scale high-solids complete-mix batch-fed anaerobic digestion process are used to estimate the first-order rate constant for the biodegradable fraction of municipal solid waste.     

The significance of ATP in the settlement of activated sludge

A laboratory-scale activated sludge plant treating simulated coke oven liquors was used to examine the settleability of the sludge in relation to its ATP concentration. On the basis of the data obtained a model was developed which described sludge settlement and was based on Monod kinetics and sludge activity (measured as ATP). The model was tested against data obtained previously from a sewage-fed plant.     

受控堆肥条件下可降解材料最终需氧生物分解能力测定的不确定度评定研究

基于可降解塑料的降解性能测试周期长、影响因素多导致其不确定度评定的过程较为复杂的原因,对受控堆肥条件下材料最终需氧生物分解百分率（D_t）开展了不确定度评定,并根据各不确定度分量的合成方法,对其进行归一化及可视化处理,得到D_t的主要不确定度分量为f_{试验组重复性}、f_{空白组重复性}、碳原子摩尔质量（M_C）位数修约、f_TC重复性和m_TC。通过对试验进行优化后的结果表明,使D_t的不确定度分量集中在f_{试验组重复性}、f_{空白组重复性}和f_TC重复性3项A类标准不确定度上,其他的不确定度分量由于占比较小,均可忽略;简化后D_t的标准不确定度,只需要通过3项A类标准不确定度评定就能快速计算得到,省去了需要根据试验周期计算每天试验所产生的不确定度分量;简化计算得到的结果包含了90 %以上的经完整计算得到u_c（D_t）,为可降解塑料降解性能测试的不确定度评定提供了思路及范例。     

Vitrified and nonvitrified municipal solid wastes as ordinary Portland cement (OPC) and sand substitution in mortars

This work aims to evaluate the potential suitability of nonvitrified and vitrified bottom ashes to serve as substitute materials for both OPC and sand in mortars on an industrial scale. Three bottom ashes were selected as OPC substitutes: one was vitrified inside the incinerator plant (W1-C), one was carbonated under ambient conditions for 3 months (W2-C), and part of the carbonated bottom ash was further washed with Ca(OH)2 (W2-W-C). Composition and phases of the bottom ash sources were assessed by XRF and XRD, respectively. Thereafter, mortars were prepared by replacing 10, 20 or 30 wt% of OPC with these bottom ashes. It was shown that even though Ca(OH)₂ washing step (W2-W-C) led to an increment of the compressive strength in final mortars compared to the use of W2-C, it failed to reach the mechanical performance of OPC. On the contrary, the use of vitrified bottom ashes (W1-C) could lead to obtaining compressive strength comparable to that of standard mortar if added up to 10 wt%. Regarding the sand substitution, vitrified bottom ashes could reach suitable compressive strength when replacing 20 wt% of standard sand. The alkali aggregate reaction test confirmed the neutrality of substitution material added up to 50 wt%.     

基于图像深度学习的垃圾热值预测研究

垃圾焚烧发电厂入炉垃圾热值波动大,影响了锅炉运行的稳定性和发电效率,利用图像深度学习的方法实现入炉垃圾热值的实时预测,有助于电厂实现“超前调控”。本文探讨了国内外垃圾图像识别及热值预测的研究进展和不足,认为目前缺少符合我国垃圾组分结构的垃圾图像数据库和热值智能预测方法,提出了用Yolov5识别图像中垃圾种类来预测热值的方法,通过入炉垃圾图像的实时采集与分类标记建立图像数据库,并耦合mosaic数据增强等图像数据处理及神经网络训练,提出建立垃圾热值实时预测模型的设想。本文进一步展望了垃圾热值智能预测的发展前景,未来可以将深度学习与图像识别技术高效结合,实现入炉垃圾热值的实时与精准预测。     

城市生活垃圾热解气化技术研究进展

从城市生活垃圾热转化方式的比较入手,简要阐明了热解气化过程,讨论了各类热解气化反应器的优缺点,概述了城市生活垃圾热解、气化实验研究进展以及热解气化技术中试及应用情况。通过比较各类实验研究,明确了热解温度、加热速率对热解产物产量及产物分布的影响,气化温度、氧气当量比(RO)对含氧气化反应的影响,气化温度、水蒸气与城市生活垃圾质量比(S/M)对水蒸气气化反应的影响。指出了城市生活垃圾热解气化实验研究热点在于优化控制参数,提高反应速率,促进目标产物高值化,抑制其它产物及污染物的生成,以及城市生活垃圾热解气化技术的发展方向。     

Pyrolysis of brown coal under different process conditions

Pyrolysis tests were performed under laboratory conditions, simulating possible processes in the burning of brown coal mines. These tests focused on gaseous products of thermal decomposition of coal and how their concentrations changed depending on pyrolysis temperature. Results obtained can help to quantify the contributions of particular gases to overall explosiveness of a gaseous mixture and can explain the process of explosive gas release during conflagration.     

原位固氮剂在污泥堆肥过程中保氮机制

高温好氧堆肥技术虽然可有效处理有机固体废物,但常常会释放大量的氨气和造成氮素损失。本文以硫酸镁、磷酸二氢钾、硫酸镁+磷酸二氢钾（分别记为MgSO₄、KP和KPM处理组）为原位固氮剂,污泥和木屑为原料,进行高温好氧堆肥试验,研究以上原位固氮剂对污泥堆肥过程中的氨气挥发和氮素损失的影响。结果表明,硫酸镁（MgSO₄）对物料pH有显著的降低效应,添加硫酸镁使堆体高温期pH降低至8.17,低于硫酸镁+磷酸二氢钾（KPM）组（8.55）和对照（CK）组（8.90）。与CK相比,MgSO₄和KPM的NH₃累积释放量分别降低了34%和28%,反而KP组增加了35%。对比不同条件下XRD图谱可知,MgSO₄的固氮效应并不是由于MgNH₄PO₄·6H₂O的生成,而是由于其对pH的降低效应造成的。堆肥结束后,除了KP组,各处理条件下的种子发芽率值（germination index,GI）均不会对后续使用带来不利影响。     

Simultaneous removal of organic substances and nitrogen using amembrane bioreactor seeded with anaerobic granular sludge under oxygen-limited conditions

An innovative process, the oxygen-limited membrane bioreactor seeded with anaerobic granular sludge, wasproposed and its performance investigated for concurrent removal of organic substances and nitrogen from synthetic domestic wastewaters. An air diffuser was installed just above the granular sludge bed to supply air to the reactor at an intermittent mode. The internal recycle from the upper part of the reactor to the bottom was introduced to provide the granular sludge bed under the oxygen-limited conditions. The oxygen addition rates were controlled at 3-4 g O₂ 1⁻¹d⁻¹. The total COD removal efficiency of more than 94% was achieved throughout the whole operation period. N was removed through the simultaneous nitrification and denitrification process that took place in the granular sludge bed. TN levels decreased with the decrease of ammonium levels, indicating that nitrification was the rate-limiting step. The TN removal efficiency reached 80-91% at an hydraulic retention time of 15 h. Nitrate was scarcely detected and nitrite was the main NO_x-N species in the effluent, indicating that nitrite oxidizers were inhibited in the system.     

城市固体生活垃圾微波裂解固体残留物制备活性炭

利用城市固体垃圾微波裂解固体残留物制备活性炭。固体残留物通过物理筛选,浮选的预分离,再用酸碱化学法将其中的杂质除去,然后用水蒸气物理活化法活化,最后制备出活性炭。对制备出的活性炭进行性能检测,结果显示：经过物理和化学分离提纯,原炭料碳含量由28．79％提高到81．50％;制备出的活性炭的吸碘值在587mg／g,比表面积591m2／g,亚甲值67mg／g。     

Dry anaerobic batch digestion of the organic fraction of municipal solid waste

Anaerobic digestion at high solid concentrations (dry anaerobic digestion) is an attractive method for the stabilization of solid organic wastes. A new concept for dry anaerobic batch digestion (BIOCEL) of the organic fraction of municipal solid waste is presented. The start up of a BIOCEL reactor was studied with several methods of process set up and operation. Dry anaerobic digestion of the pure undiluted organic fraction obtained from a shredding/separation process was not accelerated by partial spatial separation of substrate and methanogenic inoculum (granular sludge) or leachate recycle, or both. With these three methods after 30 days the high organic acids concentration and low pH in the reactor indicated a sour reactor, unable to establish significant methane production. When the organic fraction was digested in combination with compost addition (40% (w/w) of the initial solids) and leachate recycle, the stabilization rate increased significantly. Leachate recycling in combination with partial spatial separation of the substrate/compost mixture and the inoculum showed the shortest lag phase in the methane production and the shortest digestion time. When the digested residue of a completed digestion was applied as the methanogenic inoculum (40% (w/w) of the initial total solids) the digestion time was slightly shorter. It is concluded that dilution with compost had a positive effect on the start up of the dry anaerobic digestion and compensated for a suboptimal amount of initial methanogenic biomass. During the start up of dry anaerobic batch digestion of municipal solid waste the rapid recovery of methane formation from an initial overloading was observed and was found to be the result of a population shift in the methanogenic biomass and the existence of zones in the reactor with more optimal conditions (higher p H, lower organic acids concentration). The observed digestion time was 36 days. Recommendations are given to shorten the period needed, for complete digestion.