【作者】 李艳宾；

【导师】 张磊；

【作者基本信息】 西南大学 ， 微生物学， 2007， 硕士

【摘要】 重庆市地处我国沿长江带柑橘优势产业区，橙汁加工能力达25万吨，位居亚洲第一，每年产生约25万吨的柑橘皮渣。大量的橘渣至今仍采用填埋的方式处理，不但占用了大量宝贵的土地资源，同时对三峡库区的生态环境造成巨大的威胁。柑橘皮渣处理的问题已经迫在眉睫，产业化处理新技术亟待开发。厌氧消化技术是处理有机废物理想的方法，国外有过利用柑橘皮渣进行厌氧消化的报道，但研究不多，而国内则并未开展相关工作。本研究的目的是探讨柑橘皮渣厌氧消化处理的可行性，并对主要工艺参数进行优选，以期为柑橘加工废料的高效厌氧消化工艺的建立提供参考。研究的主要结果如下：1．对柑橘皮渣的含水量、挥发性固体（VS）含量、C／N比、微量元素等特性进行了详尽分析，对照猪粪等常见物料的特性后，确定在以后的试验中均采用猪粪作为配料以促进柑橘皮渣的厌氧消化，并以尿素调节料液C／N比至25：1；对柑橘皮渣进行40 d的酸化试验，期间不调节pH值，每3d检测料液中有机挥发酸（VFA）含量，结果表明柑橘皮渣具有酸化过程快、周期短、产酸量大、料液pH过低的特点，提出以碱液调节料液pH和适当降低料液浓度两个方面来解决上述问题；2．采用以猪粪为发酵原料稳定产气的沼气池污泥为接种物，每10d加入一定量的柑橘渣浸出液进行驯化，周期40d。结果表明，驯化后污泥的形态和其中的微生物优势菌群均发生了变化，说明驯化起到了很好的作用，污泥因物料性质的改变而逐渐适应；3．设置柑橘皮渣：猪粪为8：2、7：3、6：4、5：5四个处理，研究猪粪不同添加量对发酵的影响。结果表明在料液浓度为6％、pH值在7.0左右、接种物的接种量为原料干物质重量的20％、发酵周期为30 d时，除8：2的处理较差外，其余各处理的产气与沼气质量并无显著差异，而从各处理COD的去除情况来看，8：2、7：3两处理最好。综合比较，7：3的处理既保证了沼气产量与质量，又有较高的橘渣比例，此时总产气量、日均产气量、TS产气率、VS产气率、池容产气率等分别为11918.67 ml、397.29 ml、49.60 ml·g^-1、58.56 ml·g^-1、0.10ml·ml^-1d^-1，甲烷含量53.23％，达到沼气甲烷含量正常范围（50-70％），COD去除率40.93％(44788.80 mg·L^-1，初始浓度，下同)。因此以后试验均采用橘渣：猪粪为7：3的比例；4．对料液浓度分别为2％、3％、4％、6％、8％的物料进行为期30 d的室温发酵试验，橘渣：猪粪为7：3，其余条件同前。结果表明，当浓度达到8％时，由于负荷过高而使发酵受阻。料液浓度过低，也将影响发酵产气、沼气质量以及有机质去除。试验中6％的处理最好，其总产气量、日均产气量、TS产气率、VS产气率、池容产气率等分别为10481.44 ml、349.38ml、42.96 ml·g^-1、49.34 ml·g^-1、0.09 ml·ml^-1d^-1，甲烷含量51.94％，COD去除率44.12％(45145.58 mg·L^-1)。故以6％的料液浓度作为以后试验的投料标准；5．设计了堆沤预处理试验。结果表明，当对原料堆沤5 d时，总产气量、日均产气量、TS产气率、VS产气率、池容产气率等分别达到：12058.21 ml、401.94 ml、50.16ml·g^-1、57.61 ml·g^-1、0.10 ml·ml^-1d^-1，比不堆沤均有显著（P＜0.05）提高，甲烷含量也较高，达到54.91％，COD去除率为47.79％(44419.33 mg·L^-1)。当堆沤时间达到10 d时，产气出现了下降的趋势，而气体CH₄含量、COD去除率等也没有明显的提高。说明，适当的堆沤，能促进柑橘皮渣的厌氧消化，但堆沤时间过长，也不利于发酵的进行；6．探讨了柑橘皮渣厌氧消化的有机负荷。结果表明，比较适合的有机负荷率大约在1.0 g VS·L^-1·d^-1左右，此时总产气量、日均产气量、TS产气率、VS产气率、池容产气率等分别达到：13773.32 ml、459.11 ml、69.07 ml·g^-1、79.68 ml·g^-1、0.11 ml·ml^-1d^-1，CH₄含量63.10％，明显好于0.5 g VS·L^-1·d^-1的处理。提高负荷率至1.5 g VS·L^-1·d^-1时，表现出有机负荷过大的迹象，此时产气量和气体质量反而都有一定程度的降低：7．探讨了不同pH调节剂对发酵产气及沼气质量的影响。结果表明，在不同的有机负荷下，以NaHCO₃溶液调节能够获得相对较高的产气量，但其气体中的CH₄含量却最低；NaOH、NaHCO₃两种溶液调节效果近似，但前者气体中的CH₄含量要明显高于后者。经比较，认为以NaOH调节维持料液pH为最佳选择；8．选择半连续发酵工艺，采用正交试验方法，研究了原料堆沤时间、补料时间、补料量3个发酵影响因子对新鲜榨汁柑橘渣厌氧消化的影响。结果表明，在柑橘皮渣常温连续单相厌氧消化过程中，补料量是影响产气率的最关键因素，在补料量为2.5-7.5％的范围内，日均产气量随补料量的增大而增加；原料堆沤是影响发酵产气的又一重要因素，堆沤5 d可显著（P＜0.05）提高日均产气量；补料时间的影响最小，8-12 d补料对日均产气量没有显著的影响。各处理气体中CH₄含量无显著差异。试验的实际最佳组合为原料堆沤5 d、10 d补料、补料量为总有效容积的7.5％。此时总产气量、日均产气量、TS产气率、VS产气率、池容产气率等分别达到：18140.18 ml、604.67 ml、71.79 ml·g^-1、78.95 ml·g^-1、0.15 ml·ml^-1d^-1，CH₄含量57.22％，COD去除率为46.77％(46010.00 mg·L^-1)；9．在上述试验的基础上研究了温度对发酵产气的影响。经统计分析表明，温度变化对沼气产量的影响显著，二者之间具有较好的线性关系，揭示出稳定、较高的温度有利于发酵的顺利进行。因此，在综合衡量处理成本的基础上，可以考虑通过控制温度来提高处理效率；10．最后，根据上述试验结果提出柑橘皮渣常温厌氧消化的最佳工艺路线：鲜料中添加30％猪粪，堆沤5 d投料，发酵料液浓度6％，接种20％（接种物占发酵原料干物质重的百分比）经柑橘皮渣浸出液驯化的沼气池污泥，每10 d补料，补料量为总有效容积的7.5％。更多还原

【Abstract】 Chongqing locates in citrus advantage industry park along Yangtze River strip, which possesses the ability to process orange juice 250 thousands tons, firstly of Asia, and also 250 thousands tons citrus pulp may be produced every year. Plenty of citrus pulp were still treated as the mode of landfill up to the present, this mode occupied mass soil resources, and threatened the entironment of Three Gorges Region. How to deal with so many citrus pulp comes being an urgency problem to our country, explore new technology to dispose all these residues become necessary. Anaerobic digestion is an ideal technique to deal with organic wastes. It was reported that anaerobic digestion technique had applied in treatments of citrus pulp abroad, but only a few research had developed, analogous work still hasn’t developed in China. This research explore to seek for the feasibility of citrus pulp anaerobic digestion, select main technics parameters, and provide foundation of building high effective anaerobic digestion technics citrus wastes process. The main results list as follows:1. Water content, volatility solid content, C/N compare and trace element were analyzed, contrast to materiel characteristics of swine feces, it was determined to apply swine feces to promote anaerobic digestion of citrus pulp, and adjust fluid C/N compare to 25: 1. Acidification experiment of citrus pulp was developed in 40 d, pH value hadn’t been modulated during the period, VFA content were examined every 3 days. The results showed that citrus pulp was acidified with high speed, short cycle, high acid production and much low pH value. So, proposals were put forward that applied lye to modulate pH value and reduced fluid concentration to resolve the problems mentioned above;2. Sludge, collected from biogas digester that fermented with swine feces and producing gas stably, inoculated citrus pulp, domesticated with lixivium of citrus pulp every 10 days, the cycle was 40 days. Results indicated that after domestication, sludge configuration and predominant microbes were changed, revealed domestication gave positive effects, made sludge adapt to materiel characteristics;3. Four treatments of citrus pulp: swine feces （8:2, 7:3, 6:4, 5:5） were set to investigate effects of different proportion of swine feces on fermentation process. The results indicated that when fluid concentration was 6%, pH value was about 7.0, and inoculum size was 20% of dry material weight, the biogas production and quality in every treatment except pulp: swine feces 8:2 showed no significance. The treatments of pulp: swine feces 8:2, 7:3 utilized organic matter best. Totally, the treatment of pulp: swine feces 7:3 ensured production and quality of biogas, and owned high proportion of citrus pulp, which gained total gas production, daily average gas production, TS gas generation, VS gas generation and tank volume gas generation were 11918.67 ml、397.29 ml、49.60 ml·g^-1、58.56 ml·g^-1、0.10 ml·ml·d^-1 separately, methane content was 53.23%, （in the normal range of methane content 50-70%）, removal of COD was 40.93%, (44788.80 mg·L^-1, the beginning concentration, the same below). So the treatment of pulp: swine feces 7:3 was chosen for later experiments;4. A fermentation experiment under room temperature was carried out for about 30d, which set the fluid concentration 2%, 3%, 4%, 6%, 8%, pulp: swine feces 7:3, and other condition same the study before. Results showed that if fluid concentration was 8%, the fermentation process. blocked because of high organic loading, while too low concentration exhibited negative effects on gas production, gas quality and utilization of microbes. Treatment of fluid concentration 6% was best, its total gas production, daily average gas production, TS gas generation, VS gas generation and tank volume gas generation were 10481.44 ml、349.38 ml、49.96 ml·g^-1、49.34 ml·g^-1, 0.09 ml-ml^-1d^-1 separately, methane content was 51.94%, removal of COD was 44.12%(45145.58 mg·L^-1). So 6% of fluid concentration was chosen for later experiments;5. In pre-process of pile fermentation, when pile fermented 5 d, the total gas production, daily average gas production, TS gas generation, VS gas generation and tank volume gas generation were promoted significantly, which reached 12058.21 ml, 401.94 ml, 50.16 ml·g^-1, 57.61 ml·g^-1; 0.10 ml·ml^-1d^-1 differently, and methane content reached 54.91%, removal of COD was 47.79%(44419.33 mg·L^-1). Once the pile fermentation time was beyond 10d, gas production declined, and methane content and COD removal rate didn’t increased. It can be concluded that a timing pile fermentation can boost anaerobic digestion of citrus pulp;6. Organic loading of citrus pulp was examined, and the adaptive one was about 1.0 g VS·L^-1·d^-1 , the total gas production, daily average gas production, TS gas generation, VS gas generation and tank volume gas generation were reached 13773.32 ml, 459.11 ml, 69.07 ml·g^-1, 79.68 ml·g^-1, 0.11 ml·ml^-1·d^-1 differently, methane content was 54.91%, much higher than in treatment of 0.5 g VS·L^-1·d^-1 If feed-adding quantity reached, appeared organic loading too high, gas production and quality decreased on the contrary;7. Effects of different pH modulator on gas production and quality were examined. The results revealed under different organic loading, high gas production and low methane content were gained when using NaHCO₃, impacts of NaOH was similar to NaHCO₃, but the methane content was much higher than the latter. So, NaOH was chosen as the best modulator;8. Orthogonal test was used to check the effects of pile fermentation time, feed-adding time and feed adding quantity on anaerobic digestion on fresh citrus pulp. The results showed that at the process of citrus pulp anaerobic digested continuously in single-phase system at ambient temperature, feed-adding quantity was the key factor to influence the ratio of gas production, at the range of 2.5-7.5% feed-adding quantity, the daily average gas production promoted as feed-adding quantity increased. In addition, pile fermentation was another important factor affecting gas production, the daily average gas production was enhanced significantly （P<0.05） when pile fermented 5 d. Feed-adding impacted least, which had no significant effects on daily average gas production when feed-adding 8-12 d, CH₄ content in every treatments exhibited no significance. The best resultant lead to highest daily average gas production was pile fermentation 5 d, feed-adding 10 d, and feed-adding quantity 7.5% of total efficiency capacity，which possessed the total gas production, daily average gas production, TS gas generation, VS gas generation and tank volume gas generation were 18140.18 ml、604.67 ml、71.79 ml·g^-1: 78.95 ml·g^-1、0.15 ml·ml·（-1）d^-1, CH₄ content 57.22%, removal of COD was 46.77%(46010.00 mg·L^-1);9. On the foundation of experiments former, effect of temperature on gas production was studied. Results revealed that temperature change affected gas production significantly, they had fine linear relation between each other, indicated stable and high temperature benefit fo’r fermentation process. Considering the cost, it was suggested that control temperature to improve fermentation efficiency;10. Above all, the best technics can be advanced: adding swine feces 30% in fresh materiel, pile fermentation 5 d, with fluid concentration 6%, inoculating sludge domesticated by citrus pulp lixivium 20% （the percentage of inoculant in dry fermenting material） , feed-adding every 10d, and the quantity is 7.5% of total efficiency capacity.更多还原