沼气发电中沼气发酵的基本条件：沼气是多种厌氧性细菌发酵分解有机物质产生的，丰富的有机物质在隔绝空气和保持一定水分、温度的条件下，便能生成沼气。于是人们对沼气的产生过程进行了深入研究，逐步弄清了人工制取沼气的工艺条件。人工制取沼气，建议创造厌氧发酵的基本条件，若不具备相用的条件将得不到沼气或得到很少。这些基本条件是：

The basic conditions for biogas fermentation in biogas power generation: Biogas is produced by the fermentation and decomposition of organic matter by various anaerobic bacteria. Rich organic matter can generate biogas under the conditions of isolating air and maintaining certain moisture and temperature. So people conducted in-depth research on the production process of biogas and gradually clarified the process conditions for artificially producing biogas. To artificially produce biogas, it is necessary to create the basic conditions for anaerobic fermentation. Without the necessary conditions, biogas cannot be obtained or very little can be obtained. These basic conditions are:

一、严格的厌氧环境一密封的厌氧发酵池

1、 Strict anaerobic environment - a sealed anaerobic fermentation tank

分解有机物质产生沼气的细菌是产甲烷菌，都是厌氧性细菌，对氧非常敏感，它们在生长、发育、繁殖、代谢等生命活动中都不需要空气，空气中的氧气会使其生命活动受到抑制，甚至死亡。产甲烷菌只能在严格厌氧的环境中才能生长。所以，修建沼气池，要严格密闭，不漏水，不漏气，这是制取沼气的关键。这不仅是收集沼气和贮存沼气发酵原料的需要，也是保证沼气微生物在厌氧的生态条件下生活得好，使沼气池能正常产气的需要。

The bacteria that decompose organic matter to produce biogas are methanogens, which are anaerobic bacteria that are particularly sensitive to oxygen. They do not require air for their growth, development, reproduction, metabolism, and other life activities. The oxygen in the air can inhibit their life activities and even cause death. Methanogenic bacteria can only grow in strictly anaerobic environments. So, when building a biogas digester, it must be strictly sealed, leak free, and leak free, which is the key to producing biogas. This is not only necessary for collecting biogas and storing biogas fermentation materials, but also for ensuring that biogas microorganisms live well under anaerobic ecological conditions, so that biogas digesters can produce gas normally.

二、适宜的发酵原料和质优量足的菌种

2、 Suitable fermentation materials and high-quality and abundant bacterial strains

沼气发酵原料是产生沼气的物质基础，又是沼气细菌赖以生存的营养来源，各种有机物质如人畜粪便、作物秸秆、树叶杂草、生活污水、含有机物质的工业废渣等，都可以作为沼气池发酵的原料。沼气技术，沼气设备但细菌对营养物质中的碳素、氮素需要量建议维持适当的比例：碳氮比例配成25：1-30：1。人畜粪便和作物秸秆是主要的发酵原料。人畜和家禽粪便富含氮元素，称“富氮原料”。这类原料经过人和动物肠胃系统的充分消化，一般颗粒细小，含水量较高，容易厌氧分解，产气快，发酵期短。秸杆。稻草、菜蔓、枇壳等农作物的残余物，这些原料富含纤维素、半纤维素、果胶以及难降解的木质素和植物蜡质，称“富碳原料”。干物质含量比富氮原料高，发酵前一般需经物理、化学、生物三步预处理。富碳原料其厌氧分解比富氮原料慢，产期周期长，产气量高。氮素是构成微生物细胞质的重要原料，碳素不仅构成微生物细胞质，而且提供生命活动的能量。发酵原料的碳氮比不同，因发酵细菌消耗碳的速度比消耗氮的速度要快25～30倍。可以使沼气发酵在合适的速度下进行。如果比例失调，就会使产气和微生物的生命活动受到影响。因此，制取沼气不仅要有充足的原料，还应注意各种发酵原料碳氮比的合理搭配。

The raw materials for biogas fermentation are the material basis for producing biogas, as well as the nutritional source for biogas bacteria to survive. Various organic substances such as human and animal manure, crop straw, leaves and weeds, domestic sewage, and industrial waste containing organic substances can all be used as raw materials for biogas digester fermentation. Biogas technology and equipment require bacteria to maintain an appropriate ratio of carbon and nitrogen in nutrients: the carbon to nitrogen ratio should be set at 25:1-30:1. Human and animal manure and crop straw are the main fermentation materials. Human, livestock, and poultry manure are rich in nitrogen elements, known as "nitrogen rich raw materials". This type of raw material is fully digested by the gastrointestinal system of humans and animals, with generally small particles, high water content, easy anaerobic decomposition, fast gas production, and short fermentation period. Straw. The residues of crops such as straw, vines, and shells are rich in cellulose, hemicellulose, pectin, as well as recalcitrant lignin and plant wax, known as "carbon rich materials". The dry matter content is higher than that of nitrogen rich raw materials, and generally requires three steps of physical, chemical, and biological pretreatment before fermentation. The anaerobic decomposition of carbon rich raw materials is slower than that of nitrogen rich raw materials, with a longer production cycle and higher gas production. Nitrogen is an important raw material for the formation of microbial cytoplasm, while carbon not only constitutes microbial cytoplasm but also provides energy for life activities. The carbon to nitrogen ratio of fermentation materials varies, as fermentation bacteria consume carbon 25-30 times faster than nitrogen. It can enable biogas fermentation to proceed at an appropriate speed. If the proportion is imbalanced, it will affect the production of gas and the life activities of microorganisms. Therefore, in order to produce biogas, it is not only necessary to have sufficient raw materials, but also to pay attention to the reasonable combination of carbon and nitrogen ratios of various fermentation materials.

沼气发酵微生物是人工制取沼气和内因条件，一切外因条件都是通过个基本的内因条件才能起作用。因此，沼气发酵的前提条件就是要接入含有大量这种微生物的接种物。新鲜原料入池发酵，若加入的菌种很少，厌氧发酵停滞期很长，则迟迟不产气或产气少。采用预先沤制过的原料，并加入少量沼气污泥进行发酵，甲烷含量很快上升。说明厌氧发酵建议有大量菌种。

Biogas fermentation microorganisms are the artificial production of biogas and internal conditions, and all external conditions can only work through a basic internal condition. Therefore, the prerequisite for biogas fermentation is to introduce inoculants containing a large amount of these microorganisms. Fresh raw materials are fermented in the pool. If there are few added bacterial strains and the anaerobic fermentation has a long stagnation period, it will result in delayed or insufficient gas production. Using pre fermented raw materials and adding a small amount of biogas sludge for fermentation, the methane content quickly increases. Anaerobic fermentation requires a large number of bacterial strains.

三、沼气发酵的重要外因条件一温度、水分

3、 Important external factors for biogas fermentation: temperature and moisture

沼气发电而发酵时温度的高低直接影响原料的消化速度和产气率，温度适宜则细菌繁殖旺盛，活力强，厌氧分解和生成甲烷的速度就快，产气就多。适宜沼气发酵的温度范围较广，一般8～70℃，大多能产生沼气。低于10℃或者高于60℃，都严重抑制微生物生存、繁殖、影响产气。根据实际情况，人们把沼气发酵划分三个发酵区：即10～30℃为常温发酵区，33-38℃为中温发酵区，50～55℃为高温发酵区。农户通常采用的是常温发酵工艺。在这一温度范围内，一般温度愈高，微生物活动愈旺盛，产气量愈高。微生物对温度变化十分敏感，温度突升或突降，都会影响微生物的生命活动，使产气状况恶化。这就是为什么沼气池在夏季，非常是气温非常高的7月产气量大，而在冬季非常冷的1月产气很少，甚至不产气的原因。

The temperature during fermentation of biogas power generation directly affects the digestion rate and gas production rate of raw materials. If the temperature is suitable, bacteria will grow vigorously and have strong vitality. The speed of anaerobic decomposition and methane production will be faster, resulting in more gas production. The temperature range suitable for biogas fermentation is relatively wide, generally between 8-70 ℃, which can produce biogas. Temperatures below 10 ℃ or above 60 ℃ severely inhibit the survival, reproduction, and gas production of microorganisms. According to the actual situation, people divide biogas fermentation into three fermentation zones: the normal temperature fermentation zone at 10-30 ℃, the medium temperature fermentation zone at 33-38 ℃, and the high temperature fermentation zone at 50-55 ℃. Farmers usually use room temperature fermentation technology. Within this temperature range, generally the higher the temperature, the more vigorous the microbial activity and the higher the gas production. Microorganisms are highly sensitive to temperature changes, and sudden increases or decreases in temperature can affect their life activities and worsen gas production. This is why biogas digesters produce a large amount of gas in summer, especially in the hottest month of July, while producing very little or even no gas in the coldest month of January in winter.

四、适宜的酸碱度

4、 Appropriate pH level

沼气微生物的生长、繁殖，要求发酵原料的酸碱度保持中性，或者微偏碱性，过酸、过碱都会影产气。测定表明，酸碱度在pH=6-8之间，均可产气，以pH=6．5-7．5产气量非常高，pH低于6或高于9时均不产气。在正常的发酵过程中，沼气池内的酸碱度变化可以自然进行调解，先由高到底，然后又升高，非常后达到恒定的自然平衡（即适宜的pH），一般不需要进行人为调节。只有在配料和管理不当，使正常发酵过程受到破坏的情况下，才可能出现有机酸大量积累，发酵料液过于偏酸的现象。此时，可取出部分料液，加入等量的接种物，将积累的有机酸转化为甲烷，或者添加适量的草木灰或石灰澄清液，中和有机酸，使酸碱度恢复正常。

The growth and reproduction of biogas microorganisms require that the acidity and alkalinity of the fermentation materials remain neutral or slightly alkaline. Excessive acidity or alkalinity can affect gas production. The measurement shows that gas can be produced within the pH range of 6-8, with the highest gas production occurring at pH 6.5-7.5. No gas is produced when the pH is below 6 or above 9. In the normal fermentation process, the pH changes in the biogas digester can be naturally regulated, starting from high to low, then rising again, and finally reaching a constant natural equilibrium (i.e. suitable pH), generally without the need for manual adjustment. Only when the ingredients and management are improper and the normal fermentation process is disrupted, can there be a large accumulation of organic acids and excessive acidity in the fermentation broth. At this point, a portion of the feed solution can be taken out and an equal amount of inoculum can be added to convert the accumulated organic acids into methane, or an appropriate amount of plant ash or lime clarification solution can be added to neutralize the organic acids and restore the pH to normal.

五、严格控制阻抑物含量

5、 Strictly control the content of inhibitory substances

沼气细菌很容易受到阻抑物的影响，抑制沼气细菌的生命活动，防碍产气。沼气池内挥发酸浓度或氨态氮浓度过高，对发酵菌有抑制和阻抑作用。因此不能投入农药、油毡、电石、及含有阻抑物的废渣、废液、废水等。

Biogas bacteria are easily affected by suppressants, which inhibit their life activities and hinder gas production. Excessive concentration of volatile acid or ammonia nitrogen in biogas digesters can have inhibitory and blocking effects on fermentation bacteria. Therefore, pesticides, oil felt, calcium carbide, and waste residues, liquids, and wastewater containing inhibitors cannot be used.

六、持续的搅拌

6、 Continuous stirring

适当的搅拌方式和强度，可以使发酵原料分布均匀，增强微生物与原料的接触，防止浮渣增厚和结壳，提高原料的利用率及能量转换效率，并有利于气泡的释放，使之获取营养物质的机会增加，活性增强，生长繁殖旺盛，从而提高产气量。采用搅拌后，平均产气量可提高30％以上。

Appropriate stirring methods and intensities can evenly distribute fermentation materials, enhance the contact between microorganisms and raw materials, prevent thickening and crust formation of floating slag, improve the utilization rate and energy conversion efficiency of raw materials, and facilitate the release of bubbles, increasing their chances of obtaining nutrients, enhancing their activity, and promoting vigorous growth and reproduction, thereby increasing gas production. After mixing, the average gas production can be increased by more than 30%.