生物脱硫系统的目的在于降低沼气中的硫化氢含量。硫化氢在燃烧过程中转化成二氧化硫，对环境造成污染。大气污染物控制标准中明确规定了污染物排放到大气中的极限含量值：硫化氢4mg/m?，二氧化硫15mg/m?（德国TA-Luft标准）一般来说，当排放1500ppm的硫化氢时，将相当于产生4250mg/m?二氧化硫，应该先脱硫再进行沼气能源利用。

The purpose of a biological desulfurization system is to reduce the hydrogen sulfide content in biogas. Hydrogen sulfide is converted into sulfur dioxide during combustion, causing environmental pollution. The air pollution control standards clearly specify the limit content value of pollutants emitted into the atmosphere: hydrogen sulfide 4mg/m?, Sulfur dioxide 15mg/m? Generally speaking, when emitting 1500ppm of hydrogen sulfide, it is equivalent to producing 4250mg/m according to the German TA Luft standard? Sulfur dioxide should be desulfurized first before biogas energy utilization.

一般常规的沼气锅炉、沼气发电机组，对H2S的进气浓度要求是200ppm（或300mg/m?）。生物脱硫系统的作用在于使沼气中的硫化氢含量降至300mg/m?(200ppm)，以此来避免硫化氢对后续沼气利用设备（如发电机、锅炉等）的腐蚀作用。通过脱硫塔净化后的沼气相对湿度为100%（绝对湿度约为40g水/m?），温度介于29-38℃之间。因此，生物脱硫后的沼气，应考虑适当的冷凝后收集排放冷凝水，或另行设置冷干、增压处理。

Generally, conventional biogas boilers and biogas generators require an inlet H2S concentration of 200ppm (or 300mg/m?). The function of a biological desulfurization system is to reduce the hydrogen sulfide content in biogas to 300mg/m? (200ppm) to avoid the corrosive effect of hydrogen sulfide on subsequent biogas utilization equipment (such as generators, boilers, etc.). The relative humidity of the purified biogas through the desulfurization tower is 100% (absolute humidity is about 40g water/m?), and the temperature ranges from 29 to 38 ℃. Therefore, for the biogas after biological desulfurization, appropriate condensation should be considered to collect and discharge condensate water, or separate cold drying and pressurization treatment should be set up.

脱硫系统一个主要特点是专属性—即仅仅去除沼气中的硫化氢，而不会去除其它成分。生物脱硫运行的同时，沼气中的二氧化碳含量也因此降低。沼气的质量提高，排放到大气中的二氧化碳便相应减少。在脱硫过程中，利用不同气体成分的溶解性和可降解性差异分离硫化氢。例如：甲烷作为沼气的主要成分，在25℃时的亨利系数（气体在水中的溶解度）比硫化氢低80倍。

A major characteristic of desulfurization systems is their specificity - that is, they only remove hydrogen sulfide from biogas without removing other components. During the operation of biological desulfurization, the carbon dioxide content in biogas also decreases as a result. The improvement of biogas quality leads to a corresponding reduction in carbon dioxide emissions into the atmosphere. During the desulfurization process, hydrogen sulfide is separated by utilizing the differences in solubility and degradability of different gas components. For example, methane, as the main component of biogas, has a Henry's coefficient (solubility of gas in water) 80 times lower than hydrogen sulfide at 25 ℃.

脱硫杆菌是以二氧化碳为碳源，因此导致了沼气中二氧化碳含量适当降低。然而脱硫过程中需要补充氧气，沼气中的甲烷随着空气中氮气的加入而下降，粗略的估算可以按照甲烷浓度下降10%，以及总的气量增加10%来做初步估算。

Desulfurization bacteria use carbon dioxide as a carbon source, which leads to an appropriate reduction in the carbon dioxide content in biogas. However, during the desulfurization process, oxygen needs to be supplemented, and the methane in biogas decreases with the addition of nitrogen in the air. A rough estimate can be made based on a 10% decrease in methane concentration and a 10% increase in total gas volume.

生物脱硫的工作机理描述如下：将一定量的空气导入含有硫化氢的沼气中，在反应器内装有大量的生物填料，它们为细菌繁殖提供充分的空间。塔体采用滴滤形式，系统水和营养液(NPK)不断循环滴滤，使得填料保持潮湿状态，并补充细菌生长繁殖所需营养。专属丝硫菌属、硫杆菌属在新陈代谢的过程中吸收硫化氢，并将硫化氢转化为单质硫，并进一步氧化为硫酸。

The working mechanism of biological desulfurization is described as follows: a certain amount of air is introduced into biogas containing hydrogen sulfide, and a large amount of biological fillers are installed in the reactor, providing sufficient space for bacterial reproduction. The tower body adopts a drip filtration form, and the system water and nutrient solution (NPK) continuously circulate for drip filtration, keeping the filling material moist and supplementing the nutrients required for bacterial growth and reproduction. Exclusive sulfur bacteria and sulfur bacteria absorb hydrogen sulfide during metabolism, convert it into elemental sulfur, and further oxidize it to sulfuric acid.

化学反应式如下：

The chemical reaction formula is as follows:

H2S + 2O2 → H2SO4

H2S+2O2 → H2SO4

2 H2S + O2 → 2 S + 2 H2O

2 H2S+O2 → 2 S+2 H2O

S +  H2O + 1.5 O2 → H2SO4

S+H2O+1.5 O2 → H2SO4

反应生成的稀硫酸在营养液的缓冲中和作用下，与营养液一起排出系统，此过程周而复始。

The dilute sulfuric acid generated by the reaction is buffered and neutralized by the nutrient solution, and is discharged from the system together with the nutrient solution. This process repeats itself.