餐厨垃圾厌氧消化处理工艺的改进和应用

近年来,随着人民生活水平的不断提高,餐厨垃圾的产量也日益增加,未经处理的餐厨垃圾不仅滋生蚊虫,而且污染水体和大气。厌氧消化工艺是目前餐厨垃圾处理中常用的一种工艺,但该工艺处理中存在着餐厨垃圾消化条件难控制的问题。本文结合具体餐厨垃圾处理工程,就厌氧消化工艺进行了改进。结果表明,系统稳定运行,处理效果令人满意。     

结晶法处理餐厨垃圾厌氧消化出水的试验研究

为满足资源化回收磷的要求,进行了结晶法处理餐厨垃圾厌氧消化出水试验研究.结果表明,对于磷酸盐、氨氮浓度较高的厌氧消化出水,不适宜采用诱导结晶法处理;采用曝气吹脱结晶法处理餐厨厌氧消化出水无需投加碱剂,可达到83.9％的磷回收率,并可部分去除氨氮,但沉降时间应大于30 min.     

CSTR反应器厌氧消化餐厨垃圾启动过程的监控

通过在线监测甲烷含量、沼气产率及离线监测pH值、溶解态COD、挥发性脂肪酸(VFA)和辅酶F420等指标,对CSTR反应器厌氧消化餐厨垃圾的启动过程进行研究。在餐厨垃圾厌氧消化启动过程中,总VFA浓度和甲烷含量首先稳定下来,它们被认为是监控厌氧反应器启动的关键参数。辅酶F420的浓度从启动初期的0.183 mmol/gVSS增加到启动后期的0.282 mmol/gVSS。因此,在厌氧反应器启动阶段,可将辅酶F420的浓度作为反映反应器运行状态的有效监控指标。     

餐厨垃圾单相厌氧消化系统酸化预警指标

针对餐厨垃圾单相厌氧消化系统极易酸化、缺乏有效预警监控指标的技术瓶颈,在中温条件下利用自行设计的单相厌氧消化反应器,进行了实验室规模的启动、连续式单相厌氧消化系统运行试验,通过深入分析表征系统酸碱抵抗能力指标的变化规律,选取挥发性脂肪酸(VFA)、碳酸氢盐碱度与总碱度的比值(BA/TA)和挥发性脂肪酸总浓度与碳酸氢盐碱...     

餐厨垃圾厌氧消化工程中沼气利用方式的选择——以四川某项目为例

目前国内餐厨垃圾主流处理技术路线是以厌氧消化产沼气用于能源再生利用为处理目标技术路线。餐厨垃圾处理工程厌氧消化产生的沼气具有火炬燃烧、提纯制CNG、内燃机发电和送至焚烧厂焚烧发电等多种利用途径,不同利用途径受到不同工程建设条件影响,同时也会影响工程建设运行的经济性。本文以四川某项目为例,从产品出路、投资成本、占地面积、运行稳定性和经济性收益等方面对不同沼气利用途径进行了比选分析,结合该项目特点确定了焚烧发电的利用途径。     

青岛市餐厨垃圾调查及特性研究

采用问卷调查方式对青岛市原市内四区（市南区,原市北区,原四方区以及李沧区）的餐厨垃圾产生及收运现状进行了调查.统计数据显示,青岛市原市内四区餐厨垃圾日产生量达600余t,餐厨垃圾分类收集率为42％,仅有50％的餐厨垃圾由环卫部门统一收运进行安全处置.青岛市餐厨垃圾管理系统存在分类收集率低,流失严重,清运设施简陋,无集中处理处置设施等问题.大量餐厨垃圾没有通过环卫部门进行统一处置,存在严重的环境卫生与食品安全隐患.青岛市餐厨垃圾理化性质分析结果表明,青岛餐厨垃圾含水率80％左右,可生化有机物占总固体含量的90％左右,C/N在10左右.根据餐厨垃圾理化性质分析,探讨了青岛市餐厨垃圾厌氧消化处理的可行性.     

颗粒活性炭强化餐厨垃圾中食用油厌氧消化产甲烷

通过投加颗粒活性炭（GAC）强化直接种间电子传递（DIET）,进而提升餐厨垃圾中常见食用油的厌氧消化产甲烷效能,并分析投加GAC对微生物群落结构的影响。研究发现,与未投加GAC的对照组相比较,投加GAC的实验组可以高效稳定地进行厌氧消化产甲烷。在菜籽油厌氧消化过程中,对照组的乙酸浓度在第7天达到最大值（7 mmol/L）,之后基本保持不变。而在投加GAC的实验组中,乙酸浓度在第7天达到最大值（3.9 mmol/L）,之后逐渐降低,到第13天基本为0。与此同时,实验组的最大甲烷产量约为对照组的3.5倍。因而,投加GAC促进了乙酸的降解和甲烷的转化。对微生物群落结构进行分析发现,投加GAC的实验组中富集了大量可能具有胞外电子传递功能的细菌（Syntrophomonas和Geobacter）,以及可以参与DIET的产甲烷菌（Methanosarcina）,表明投加GAC可以有效富集以上三种微生物,并通过GAC作为电子载体促进菜籽油厌氧反应体系中DIET的形成,进而促进菜籽油的降解,提高甲烷产量。     

北京高安屯餐厨协同污泥厌氧消化生产性试验

餐厨与污泥同属城市有机废弃物,均采用厌氧消化作为重要手段来实现资源化、减量化和稳定化。将两者协同处置,理论上可避免餐厨单独厌氧消化易酸化、污泥单独消化产气率低等问题。利用北京高安屯污泥处理中心现况污泥处理设施,开展大型生产性试验,将预处理后的餐厨浆料与污泥实施联合中温厌氧消化以验证协同处置实际效果。试验期间,协同系统稳定,协同处置效应明显,实际产气量与理论产气量基本吻合。消化池中酸碱比低于0.12,氨氮含量低于4 000 mg/L。消化池有机负荷峰值为3.399 kgVS/(m³·d)、有机物分解率平均为63.59%、分解单位有机物产气率平均为1.41 m³/kgVS、单位干固体沼气产量平均为571 m³/tDS,较单独污泥厌氧消化时分别提升2.7%、15.2%、5.2%和31%。但需注意,随着餐厨浆料比例的增加,沼气中甲烷含量略有降低。此外,还针对协同处置消化系统的进排泥操作提出了优化措施。     

pH值对餐厨垃圾厌氧产酸的影响

通过间歇试验研究了中温条件下pH值对餐厨垃圾厌氧发酵产酸的影响。考察了pH值为5、6、7及不控制pH值下的有机酸浓度、SCOD溶出量、对VS的去除率及产气情况。结果表明,当控制pH值为6时,餐厨垃圾的水解酸化效果最好,发酵液中的VFA浓度最高,达到37.60g/L。对VS的去除率在pH值为6和7时最高,分别为64.8%和64.5%。氨氮浓度在pH值为6和7时均达到2 140 mg/L,而在更低pH值时则维持在600～700 mg/L之间。pH值为6时SCOD浓度达到85 g/L,其中VFA占SCOD的72.8%;气体产量为118.9 mL/gVS,主要成分为氢气和二氧化碳,其中氢气占40.1%,二氧化碳占50.0%。     

餐厨垃圾生化处理工艺工程应用分析

结合2个工程实例,从预处理系统、微生物消化系统、污水处理系统、除臭系统以及附属设施设计和环境经济效益方面对比了厌氧消化处理工艺和好氧微生物生化机处理工艺在餐厨垃圾处理中的应用情况.分析结果表明,厌氧消化处理工艺处理每吨餐厨垃圾约消耗70～90kWh电量、0.25t水量,处理成本约150元/t,日处理量为100t的项目占...     

A comparison of wet and dry anaerobic digestion processes for the treatment of municipal solid waste and food waste

A main distinction between anaerobic digestion (AD) technologies for treatment of municipal and industrial biodegradable wastes is the operating process solids content. Wet AD systems operate at low total solids (<10–20% TS) and dry systems have high operating solids (20–>40% TS). The performance of wet and dry AD systems was quantified in relation to: technical operation (footprint, capacity, feedstock characteristics, pretreatment and post‐treatment, retention time, water usage), energy balance (biogas productivity, parasitic energy, methane [CH₄] content, utilization of biogas and produced energy), digestate management and economic performance (capital and operational costs, revenues, specific capital costs [per t of waste and per m³ biogas]). Wet AD plants had improved energy balance and economic performance compared to dry AD plants. However, dry AD plants offered several benefits, including greater flexibility in the type of feedstock accepted, shorter retention times, reduced water usage and more flexible management of, and opportunities for marketing, the end‐product.     

Application of high rate, high temperature anaerobic digestion to fungal thermozyme hydrolysates from carbohydrate wastes

The objective of this study was to examine the feasibility of using a two-step, fully biological and sustainable strategy for the treatment of carbohydrate rich wastes. The primary step in this strategy involves the application of thermostable enzymes produced by the thermophilic, aerobic fungus, Talaromyces emersonii, to carbohydrate wastes producing a liquid hydrolysate discharged at elevated temperatures. To assess the potential of thermophilic treatment of this hydrolysate, a comparative study of thermophilic and mesophilic digestion of four sugar rich thermozyme hydrolysate waste streams was conducted by operating two high rate upflow anaerobic hybrid reactors (UAHR) at 37 °C (R1) and 55 °C (R2). The operational performance of both reactors was monitored from start-up by assessing COD removal efficiencies, volatile fatty acid (VFA) discharge and % methane of the biogas produced. Rapid start-up of both R1 and R2 was achieved on an influent composed of the typical sugar components of the organic fraction of municipal solid waste (OFMSW). Both reactors were subsequently challenged in terms of volumetric loading rate (VLR) and it was found that a VLR of 9 gCOD l⁻¹ d⁻¹ at a hydraulic retention time (HRT) of 1 day severely affected the thermophilic reactor with instability characterised by a build up of volatile fatty acid (VFA) intermediates in the effluent. The influent to both reactors was changed to a simple glucose and sucrose-based influent supplied at a VLR of 4.5 gCOD l⁻¹ d⁻¹ and HRT of 2 days prior to the introduction of thermozyme hydrolysates. Four unique thermozyme hydrolysates were subsequently supplied to the reactors, each for a period of 10 HRTs. The applied hydrolysates were derived from apple pulp, bread, carob powder and cardboard, all of which were successfully and comparably converted by both reactors. The % total carbohydrate removal by both reactors was monitored during the application of the sugar rich thermozyme hydrolysates. This approach offers a sustainable technology for the treatment of carbohydrate rich wastes and highlights the potential of these wastes as substrates for the generation of second-generation biofuels.     

Nickel stimulation of anaerobic digestion

An acetate-enriched methanogenic culture was assayed for nutritional stimulation by nickel in combination with other inorganic and organic nutrients, i.e. iron, cobalt, yeast extract, riboflavin and vitamin B₁₂. Acetate was automatically maintained at 2–3 g l⁻¹ by a pH Stat system so that substrate was not limiting. In the absence of nickel, the specific acetate utilization rates were in the range of 2–4.6 g acetate g⁻¹ VSS day⁻¹. In the presence of nickel, this rate was as high as 10 and when both nickel and yeast extract were supplemented this rate temporarily increased to 12–15 g acetate g⁻¹ VSS day⁻¹ . The maximum acetate utilization rate was observed to be 51 g l⁻¹ day⁻¹ as compared to 3.3 g l⁻¹ day⁻¹ for conventional high-rate digestion. Daily phosphate additions were required to sustain these high acetate utilization rates. An acetate utilization rate of 20–30 g l⁻¹ day⁻¹ was maintained for over 25 days. Microscopic examination of the culture revealed a predominance of a sarcina whenever stimulation was noted.     

Silage effluent digestion by an upflow anaerobic filter

Silage effluent is generally regarded as one of the major agricultural pollutants of water courses. Efficient anaerobic digestion of silage effluent was achieved by a 3-day hydraulic retention in an upflow anaerobic filter. The filter was a laboratory scale unit containing a limestone chip support matrix. At loading rates ranging from 7.8 to 14.2 kg COD m⁻³ active volume day⁻¹, the average COD removal obtained ranged from 86 to 89% with a TOA removal of 82–88%. The methane content of the biogas produced ranged from 81 to 88%. The rate of COD conversion to CH₄ was independent of the loading rate under the conditions tested and the observed efficiency averaged 0.357 m¹ CH₄(STP) kg⁻¹ COD introduced to the reactor.The reactor tolerated considerable variation in influent pH without any apparent decrease in digestion efficiency. It is apparent from the results obtained that a reactor which is in routine use for slurry digestion may also be utilised for silage effluent digestion on a seasonal basis.     

Effect of waste activated sludge pretreatment methods to mitigate Gordonia foaming potential in anaerobic digestion

In this study, waste activated sludge obtained from two full‐scale treatment plants with foaming issues was pretreated with acid/alkali treatment, acid‐phase fermentation, thermal treatment, ultrasonic treatment and metal salt treatment to investigate their effect on foam mitigation. Waste activated sludge was characterized for foaming index prior and after each pretreatment method. Among all pretreatment methods investigated, acid/alkali treatment and acid phase fermentation showed highest reduction of 53% in foaming and in inactivation of Gordonia amarae filaments. Pretreatment methods that resulted in sharp decrease in the foaming index concurred with higher amounts of dead foam formers as confirmed using live/dead staining and the PMA‐qPCR technique. Pretreating with iron(III)chloride gave good foaming reductions with 54% decrease in foaming potential at a concentration of 260 mg/L but did not result in a decline of foam formers as confirmed by live/dead staining. Ultrasonic treatment did not prove effective in lowering the foaming index or killing the G. amarae filaments.     

Methane production from industrial wastes by two-phase anaerobic digestion

Although much attention has been paid to energy recovery from municipal sewage, industrial liquid waste is a larger potential source of renewable energy. In certain industrial sectors it is possible, in theory to displace almost all of the purchased fuels by recovering the energy content of the waste in suitable forms and utilizing them within the plant. Anaerobic digestion is probably the only available process that can achieve the dual goal of energy recovery from aqueous wastes and stabilization of the pollution load. This paper presents data illustrating the limitations and vulnerability of the conventional digestion process to this end, and discusses the application and advantages of an innovative and advanced fermentation system, two-phase digestion. Results of operation of bench-, pilot- and full-scale two-phase digestion plants with several types of industrial liquid wastes are presented. Industrial sectors that could benefit from commercial-scale application of this new process are indicated.     

Temperature phased anaerobic digestion increases apparent hydrolysis rate for waste activated sludge

It is well established that waste activated sludge with an extended sludge age is inherently slow to degrade with a low extent of degradation. Pre-treatment methods can be used prior to anaerobic digestion to improve the efficiency of activated sludge digestion. Among these pre-treatment methods, temperature phased anaerobic digestion (TPAD) is one promising method with a relatively low energy input and capital cost. In this study, an experimental thermophilic (50-70 °C)-mesophilic system was compared against a control mesophilic-mesophilic system. The thermophilic-mesophilic system achieved 41% and 48% volatile solids (VS) destruction during pre-treatment of 60 °C and 65 °C (or 70 °C) respectively, compared to 37% in the mesophilic-mesophilic TPAD system. Solubilisation in the first stage was enhanced during thermophilic pre-treatment (15% at 50 °C and 27% at 60 °C, 65 °C and 70 °C) over mesophilic pre-treatment (7%) according to a COD balance. This was supported by ammonia-nitrogen measurements. Model based analysis indicated that the mechanism for increased performance was due to an increase in hydrolysis coefficient under thermophilic pre-treatment of 60 °C (0.5 ± 0.1 d⁻¹), 65 °C (0.7 ± 0.2 d⁻¹) and 70 °C (0.8 ± 0.2 d⁻¹) over mesophilic pre-treatment (0.2 ± 0.1 d⁻¹), and thermophilic pre-treatment at 50 °C (0.12 ± 0.06 d⁻¹).     

谈污泥厌氧消化预处理方法

结合传统的污泥厌氧消化周期长、消化速率低的特点,综述了热、化学、生物和机械预处理方法及其在研究中对污泥厌氧消化的影响,并提出厌氧消化预处理方法的展望,以期改善污泥理化性质,提高厌氧消化效率。     

Enhancement of anaerobic batch digestion of sisal pulp waste by mesophilic aerobic pre-treatment

Pre-treatment of sisal pulp prior to its anaerobic digestion was investigated using an activated sludge mixed culture under aerobic conditions in batch bioreactors at 37 degrees C. The progression of aerobic pre-treatment of the residue in relation to the activities of some extracellular hydrolytic enzymes in the slurry was monitored. The highest activity of hydrolytic enzymes was obtained at 9 h of pre-treatment. Filter paper cellulase had a maximum activity of 0.90 IU/ml, while carboxymethyl cellulase, amylase and xylanase were produced to a maximum of about 0.40 IU/ml. The methane yield obtained after anaerobic digestion of the pre-treated pulp ranged between 0.12 and 0.24 m3 CH4/kg VS added. The highest and lowest values were obtained for 9 and 72 h of pre-treatment, respectively. Nine hours of pre-treatment of sisal pulp prior to anaerobic digestion demonstrated a 26% higher methane yield when compared to the sisal pulp without pre-treatment. The consortia of microorganisms in activated sludge demonstrated a useful potential in the production of hydrolases acting on major macromolecules of sisal pulp. The fact that a correlation was observed between high enzyme activity and high methane yield at 9 h of aerobic pre-treatment suggests that such a short pre-treatment period could be an alternative option for increasing solubilization of sisal pulp and promoting methane productivity.