餐厨垃圾高温厌氧消化连续运行性能：有机物转化效率、发酵稳定性与代谢活性

在高温 (50±1)℃条件下处理实际工程的餐厨垃圾,采用全混式厌氧反应器（CSTR）进行了80 d的连续试验。试验以水力停留时间（HRT）20 d启动,HRT 15 d连续运行,研究了反应器启动和运行期间的发酵特性,解析了餐厨垃圾厌氧消化运行稳定性和代谢活性。试验结果表明,在HRT 15 d、有机负荷（OLR）为7.3 kg_COD/(m³∙d)的条件下,容积产甲烷率为2.2 L/(L∙d),挥发性固体（VS）的甲烷产率达到480 L/kg_VS左右,有机物转化率约为95%。批次试验表明,高温产甲烷菌代谢乙酸能力较强,在适宜pH下可承受10 000 mg/L的乙酸浓度。餐厨垃圾的高温降解速率快,10 d达到90%的产气,有承受更高负荷的可能。系统pH稳定在7.6 ~ 7.7,总氨氮和自由氨浓度低于抑制水平。研究结果表明,餐厨垃圾的高温厌氧消化可实现较高的产气潜力和有机物去除率,系统稳定性好且有机物转化效率高,具有应用于工程高温餐厨垃圾厌氧处理的潜力。     

牛粪和餐厨垃圾混合两相发酵产氢产甲烷的协同作用研究

通过两相厌氧发酵批式实验,研究牛粪和餐厨垃圾在不同混合比例下（4∶0,3∶1,2∶2,1∶3和0∶4）的产氢、产甲烷和产能特性,探究混合基质发酵在两相厌氧发酵产能过程中的协同作用。研究结果表明：氢气产率、甲烷产率和能量产率均随着餐厨垃圾占比的提高而增大,混合发酵在缩短产气延迟时间和提高最大产氢产甲烷速率方面具有积极作用;氢气产率和丁酸产量呈显著正相关关系,说明混合发酵和餐厨垃圾产氢均遵循丁酸型代谢途径;牛粪单独发酵时的主要挥发性脂肪酸产物为乙酸,氢气产率很低;混合发酵产氢在牛粪和餐厨垃圾之比为1∶3时表现出协同作用,而在牛粪和餐厨垃圾之比为3∶1和2∶2时表现出拮抗作用;在产甲烷和产能方面混合发酵呈现协同作用,且协同率随牛粪占比的增加而提高;当牛粪和餐厨垃圾之比为3∶1时,产甲烷协同率和产能协同率分别为23.6%和20.4%,协同效果最显著。     

餐厨垃圾中温厌氧发酵接种污泥的驯化研究

研究不同投料方式对餐厨垃圾中温厌氧发酵接种物产气活性的影响,探求餐厨垃圾中温厌氧发酵接种物的最佳驯化方法。在37℃条件下,采用不同投料方式对厌氧污泥进行驯化作为餐厨垃圾厌氧发酵的接种物,分析驯化过程中污泥pH值和SCOD浓度的变化,并用驯化后污泥作为接种物对餐厨垃圾进行中温厌氧发酵处理,研究不同驯化方式对餐厨垃圾产气特性的影响。结果表明:污泥经过添加一定量的餐厨垃圾驯化培养后,产气活性有所提高,其中每天投2.5 g实验物料(厌氧污泥接种体占0.5%),培养20 d后的接种体中生物活性最高,平均产气效率达179.5 mL/d,甲烷气体浓度为59.8%,最终降解率为75.5%。     

餐厨垃圾与污泥共发酵脱氮技术的研究

餐厨垃圾与污泥是城市垃圾的重要组成部分,作为可再生资源,目前餐厨垃圾与城市污泥共发酵产甲烷成为国内外垃圾能源化利用的主要方法.氨氮浓度是抑制发酵效率的一个影响因素,在中温(37℃)厌氧条件下,以餐厨垃圾与污泥1:1混合发酵,为提高发酵效率,进行发酵过程中脱氮研究;试验研究了发酵过程中氨氮的变化规律,确定发酵第15天为最佳脱氮时间;建立L16(45)正交设计,研究了吹脱时间、吹脱强度、pH值、絮凝剂(PAM)添加量对脱氮的影响.对正交试验结果进行分析,得出吹脱时间为10h、pH值为12、吹脱强度为20L/h、絮凝剂(PAM)投加量为2.5 mg/0.2 L是最佳脱氮工艺条件.     

构树与不同生物质废弃物混合厌氧发酵产气性能研究

在温度(55±1℃)和总挥发性固体浓度(2%)为固定参数,碳氮比(C/N)为可变参数的条件下,研究了构树和牛粪、餐厨垃圾、水稻秸秆分别进行混合发酵的产气性能。研究结果表明:与单一发酵相比,混合发酵均能提高甲烷产量,当构树与餐厨垃圾混合物的C/N为20时,可获得最高的累积产甲烷量(411.71 mL/g),比构树和餐厨垃圾单独发酵时的累积产甲烷量分别提高了45.45%和12.61%;构树与餐厨垃圾、牛粪、水稻秸秆进行混合发酵时,原料之间均存在协同作用,其中,构树与水稻秸秆在C/N为15的条件下进行混合发酵时,协同指数最高,为18.69%;构树与不同废弃物的混合厌氧发酵过程符合修正Gompertz方程(R~20.97),可用该拟合方程模拟混合厌氧发酵过程。     

厌氧消化处理餐厨垃圾的工艺研究

在分析餐厨垃圾的性质和现有处理技术基础上，着重分析了湿式厌氧发酵工艺处理餐厨垃圾的适应性和特点，并根据餐厨垃圾的组成特性和湿式厌氧发酵反应的要求．研究了适用于餐厨垃圾的湿式厌氧发酵工艺，该工艺通过对原料处理罐（备料罐）和发酵反应器的精心设计，保证了发酵反应的顺利进行和发酵后腐熟质的质量，实验室试验表明产气率可达0．520m^3／kg．VS。     

餐厨垃圾厌氧发酵产沼气潜力及其动力学研究

采用全自动甲烷潜力测试系统(AMPTS)考察中温(37℃)和常温(25℃)条件下餐厨垃圾厌氧发酵产沼气的潜力,同时建立其动力学模型。研究结果表明:相比于常温,中温下餐厨垃圾厌氧发酵日甲烷产量峰值提高116.8%,累积甲烷产量提高143.9%,且产气周期缩短,物料降解率提高;利用Cheynoweth方程对中温厌氧发酵产甲烷过程进行动力学分析,所建模型相关系数R20.95,拟合结果与试验数据较为接近,说明Cheynoweth方程能够较好地反映餐厨垃圾产甲烷的规律。研究结果为餐厨垃圾厌氧发酵处理提供设计和运行依据。     

餐厨垃圾与市政污泥协同厌氧制氢影响因素研究

以餐厨垃圾和市政污泥为研究对象,采用协同厌氧制氢工艺研究不同温度、物料配比对厌氧产氢潜力和中间代谢产物变化规律的影响。结果表明,55℃高温发酵时,餐厨垃圾单独厌氧发酵产氢效果最佳,产氢潜力、最大产氢速率分别为342.49 mL、41.48 mL/h,是35℃中温发酵的1.2倍。35℃中温发酵,餐厨垃圾与市政污泥配比为5∶1时氢气含量最高为56.4%。相关性分析表明,pH值与氨氮浓度呈正相关,与还原糖含量、累积产氢量呈显著负相关;还原糖含量与累积产氢量呈正相关,氨氮浓度与累积产氢量呈显著负相关。温度、物料配比和pH值的优化调控对协同厌氧制氢工艺的高效稳定运行具有重要意义。     

餐厨垃圾特性及其厌氧消化性能研究

以校园餐厨垃圾为原料,分析测定了早餐、午餐和晚餐餐厨垃圾的总固体(TS)、挥发性固体(VS)、碳水化合物、蛋白质、脂肪含量以及无机盐离子浓度,并通过批式厌氧发酵试验对3种餐厨垃圾的厌氧消化性能进行了对比研究。结果表明,早餐餐厨垃圾特性与午餐/晚餐餐厨垃圾差异较大,Na+,Ca2+和Cl-含量高于后两者。餐厨垃圾不同特性对其厌氧消化产气及有机物去除率都有一定影响,早餐、午餐和晚餐餐厨垃圾的累积甲烷产量分别为212.2,331.6和362.4 ml/g,早餐餐厨垃圾产气量比午餐和晚餐餐厨垃圾分别低36%和41.4%,其中Cl-含量高可能是造成其产气量低的主要原因。     

碳材料增强微生物种间电子传递强化餐厨垃圾厌氧消化产甲烷研究综述

餐厨垃圾厌氧消化产甲烷是餐厨垃圾资源化、能源化利用的重要途径,但其有机物互营产甲烷过程易受微生物间接种间电子传递的低速瓶颈和低氢分压限制的影响,导致有机酸累积抑制、甲烷回收效率低,系统稳定性差。近年来大量研究表明,多种导电碳材料可通过介导互营微生物直接种间电子传递（DIET）,大幅提高种间电子传递速率,并突破低氢分压限制,强化餐厨垃圾厌氧产甲烷。文章在梳理有机物厌氧消化微生物种间电子传递机理的基础上,总结了活性炭、生物炭、碳布、石墨等多种导电碳材料介导微生物DIET强化餐厨垃圾厌氧消化的最新研究进展,包括碳材料对互营细菌和产甲烷菌种间电子传递、产气滞后期及甲烷产量、有机酸代谢和系统稳定性、厌氧微生物群落结构动态演化的影响。尽管外源碳材料介导DIET强化餐厨垃圾厌氧消化的优异效果已被证实,但碳材料诱导互营微生物间DIET体系建立的机理尚未明确,而且碳材料如何在大型沼气工程中持续稳定发挥功效及其回收利用问题仍未有效解决。在未来的研究中,碳材料诱导下高效DIET功能菌群的构建机制及其工程化应用将是重点研究方向。     

Production of bio‐energy from organic waste: effect of temperature and substrate composition

This article presents the influence of temperature and influent substrate composition on the produced biogas volume in an anaerobic co‐digestion process. Four cases of anaerobic digestion were considered. Digestion of waste sludge only and anaerobic co‐digestion of sludge mixed with solid waste in mesophilic (T = 35 °C) and thermophilic (T = 55 °C) phases. The obtained results show that thermophilic co‐digestion gives the best results; although the temperature has an effect on biogas production, it remains however quite relative compared to the effect of solid waste. They confirm, surely, that the combined effect of temperature and solid waste improves considerably the biogas production rate (GPR). Changing conditions from mesophilic to thermophilic ones for waste sludge alone and for waste sludge mixed with solid waste results in an increase of the GPR from 0.18 to 0.39 m³/m³.d and from 0.29 to 0.96 m³/m³.d, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

Thermophilic and mesophilic temperature phase anaerobic co-digestion (TPAcD) compared with single-stage co-digestion of sewage sludge and sugar beet pulp lixiviation

The performance of temperature phase anaerobic co-digestion (TPAcD) for sewage sludge and sugar beet pulp lixiviation (using the process of exchanging the digesting substrate between spatially separated thermophilic and mesophilic digesters) was tested and compared to both single-stage mesophilic and thermophilic anaerobic co-digestion. Two Hydraulic Retention Times (HRT) were studied in the thermophilic stage of anaerobic digestion in two temperature phases, maintaining the optimum time of the mesophilic stage at 10 days, obtained as such in single-stage anaerobic co-digestion. In this way, we obtained the advantages of both temperature regimes.Volatile solids removal efficiency from the TPAcD system depended on the sludge exchange rate, but fell within the 72.6–64.6% range. This was higher than the value of 46.8% obtained with single-stage thermophilic digestion and that of 40.5% obtained with mesophilic digestion. The specific methane yield was 424–468 ml CH₄ per gram of volatile solids removed, similar to that of single-stage mesophilic anaerobic digestion. The increase in microbial activity inside the reactor was directly proportional to the organic loading rate (OLR) (or inversely proportional to the HRT) and inversely proportional to the size of the microbial population in single-stage anaerobic co-digestion systems.     

Use of organic waste for biohydrogen production and volatile fatty acids via dark fermentation and further processing to methane

Despite the suitability of organic waste for dark fermentation (DF), anaerobic digestion (AD) counteracts its large-scale use for biohydrogen production. Therefore, 12 types of organic waste obtained from sugar, textile, food, and milk industries are investigated in batch single-stage AD and compared energetically to batch two-stage DF with subsequent AD. From the viewpoint of DF, a parametric study of mesophilic and thermophilic conditions, different substrate concentrations, and mixed cultures, i.e., granular and digested sludge, is conducted. Hydrogen yields of 90–160 L_N/kg_oDM (mean) and maximum yields of 199–291 L_N/kg_oDM are achieved with starchy and sugary wastes. Concentrations of volatile fatty acids of 9.7–14.5 g/L (mean) show the possible material uses. Thermophilic conditions are more suitable than mesophilic ones. Furthermore granular sludge is applicable for DF. The energetic comparison of the procedures demonstrates a method for assessing the applicability of waste and allows preliminary economic estimations.     

有机垃圾组分中温厌氧消化产甲烷动力学研究

以土豆、生菜、瘦肉和花生油为原料,采用批式中温厌氧消化产甲烷实验,研究了城市生活有机垃圾中淀粉类、纤维素类、蛋白质类和脂类4种典型组分的厌氧消化产甲烷特性。利用修正Gompertz方程对累积产甲烷量进行拟合,并对厌氧降解过程用一级动力学进行分析。结果表明:土豆、生菜、瘦肉和花生油的最终甲烷产量为260.1、145.7、258.4和757.2mL·gVS~(-1),延滞期分别为0、1.3、1.6和13.1d,累积甲烷产量达到最终甲烷产量80%所需的时间分别为7.2、9.6、8.1和59.7d,可生物降解度分别为74%、31%、51%和85%。从厌氧消化过程中液相的挥发性脂肪酸浓度和气相的氢气浓度以及pH监测结果表明,所有厌氧消化过程均没有中间产物的积累,适合一级动力学方程。土豆、生菜、瘦肉和花生油的厌氧降解速率常数分别为0.183、0.147、0.190和0.020d~(-1)。     

Effect of food to microorganism ratio on biohydrogen production from food waste via anaerobic fermentation

The effect of different food to microorganism ratios (F/M) (1–10) on the hydrogen production from the anaerobic batch fermentation of mixed food waste was studied at two temperatures, 35 ± 2 °C and 50 ± 2 °C. Anaerobic sludge taken from anaerobic reactors was used as inoculum. It was found that hydrogen was produced mainly during the first 44 h of fermentation. The F/M between 7 and 10 was found to be appropriate for hydrogen production via thermophilic fermentation with the highest yield of 57 ml-H₂/g VS at an F/M of 7. Under mesophilic conditions, hydrogen was produced at a lower level and in a narrower range of F/Ms, with the highest yield of 39 ml-H₂/g VS at the F/M of 6. A modified Gompertz equation adequately (R² > 0.946) described the cumulative hydrogen production yields. This study provides a novel strategy for controlling the conditions for production of hydrogen from food waste via anaerobic fermentation.     

Hydrogen-methane production from pulp & paper sludge and food waste by mesophilic–thermophilic anaerobic co-digestion

The present study focused on the mesophilic anaerobic bio-hydrogen production from PPS (pulp & paper sludge) and FW (food waste), and the subsequent anaerobic digestion of the effluent for the methane production under thermophilic conditions by a two-stage process. The maximum hydrogen yield of 64.48 mL g⁻¹ VS_fed and methane yield of 432.3 mL g⁻¹ VS_fed were obtained when PPS and FW were applied with 1: 1 VS ratio as the feedstock. No VFA were cumulated in the reactor during the period of hydrogen - methane fermentation, as well as no NH₃–N and Na⁺ inhibition were found in the process. 71%–87% removal efficiencies of SCOD were attained for hydrogen and methane co-production. pH 4.8–6.4 and alkalinity 794–3316 mg CaCO₃ L⁻¹ for H₂ fermentation, as well as pH 6.5–8.8 and alkalinity 4165–4679 mg CaCO₃ L⁻¹ for CH₄ fermentation, were achieved without any adjustment. This work showed that anaerobic co-digestion of PPS and FW for hydrogen-methane co-production was a stable, reliable and effective way for energy recovery and bio-solid waste stabilization by the two-stage mesophilic–thermophilic process.     

Heat and energy requirements in thermophilic anaerobic sludge digestion

The heating requirements of the thermophilic anaerobic digestion process were studied. Biogas production was studied in laboratory experiments at retention times from 1 to 10 days. The data gathered in the experiments was then used to perform a heat and energy analysis. The source of heat was a conventional CHP unit system. The results showed that thermophilic digestion is much faster than mesophilic digestion and therefore produces more biogas in a shorter time or at smaller digester volumes. The major part of the heating requirements consisted of sludge heating. The heat losses of the digester were only 2–8% of the sludge heating requirements. The heating requirements in thermophilic digestion are about twice those of mesophilic digestion. Therefore a CHP unit system cannot cover all of the needs for successful operation of thermophilic digestion. Heat regeneration was introduced as a solution. Heat is regenerated from the sludge outflow at a temperature of 50–55 °C and transferred to the cold inflow sludge at a temperature of 11 °C. Enough heat is regenerated in a conventional counter flow heat exchanger to bring the thermophilic process to the same level as the mesophilic one. Considering the smaller digester volumes and the relatively small investment in the regenerative equipment, the construction of thermophilic digestion systems may be a very good alternative to conventional mesophilic sludge digestion systems.     

Bio-hythane production from food waste by dark fermentation coupled with anaerobic digestion process: A long-term pilot scale experience

In this paper are presented the results of the investigation on optimal process operational conditions of thermophilic dark fermentation and anaerobic digestion of food waste, testing a long-term run, applying an organic loading rate of 16.3 kgTVS/m³d in the first phase and 4.8 kgTVS/m³d in the second phase. The hydraulic retention times (HRTs) were maintained at 3.3 days and 12.6 days, respectively, for the first and second phase. Recirculation of anaerobic digested sludge, after a mild solid separation, was applied to the dark fermentation reactor in order to control the pH in the optimal hydrogen production range of 5–6. It was confirmed the possibility to obtain a stable hydrogen production, without using external chemicals for pH control, in a long-term test, with a specific hydrogen production of 66.7 l per kg of total volatile solid (TVS) fed and a specific biogas production in the second phase of 0.72 m³ per kgTVS fed; the produced biogas presented a typical composition with a stable presence of hydrogen and methane in the biogas mixture around 6 and 58%, respectively, carbon dioxide being the rest.     

Enhancement of biohythane production from solid waste by co-digestion with palm oil mill effluent in two-stage thermophilic fermentation

Improvement of biohythane production from oil palm industry solid waste residues by co-digestion with palm oil mill effluent (POME) in two-stage thermophilic fermentation was investigated. A two-stage co-digestion of solid waste with POME has biohythane production of 26.5–34 m³/ton waste. The co-digestion of solid waste with POME increased biohythane production of 67–114% compared to digestion POME alone. Co-digestion of solid waste with POME enhanced hydrolysis constant (k_h) from 0.07 to 0.113 to 0.120–0.223 d⁻¹. The hydrolysis constant (k_h) of co-digestion was 10 times higher than the single digestion of solid waste. Clostridium sp. was predominated in the hydrogen stage, while Methanosphaera sp. was predominant in methane stage. The co-digestion of solid waste with readily biodegradable organic matter (POME) could significantly increase biohythane production with achieving the significant cost reduction for pretreatment of solid wastes.     

Hydrogen production from alcohol wastewater by an anaerobic sequencing batch reactor under thermophilic operation: Nitrogen and phosphorous uptakes and transformation

The objective of this study was to investigate hydrogen production from alcohol wastewater using an anaerobic sequencing batch reactor (ASBR) under thermophilic operation and at a constant pH of 5.5. Under the optimum COD loading rate of 68 kg/m³d, the produced gas contained 43% H₂ without methane and the system provided a hydrogen yield and specific hydrogen production rate of 130 ml H₂/g COD removed and 2100 ml H₂/l d, respectively, which were much higher than those obtained under the mesophilic operation. Under thermophilic operation, both nitrogen and phosphate uptakes were minimal at the optimum COD loading rate for hydrogen production and most nitrogen uptake was derived from organic nitrogen. Under the thermophilic operation for hydrogen production, the nutrient requirement in terms of COD:N:P was found to be 100:6:0.5, which was much higher than that for the methenogenic step for methane production under both thermophilic and mesophilic operations and for the acidogenic step for hydrogen production under mesophilic operation.