餐厨垃圾废水制备液态固氮菌肥

探讨餐厨垃圾废水用作发酵基质生产液态褐球固氮菌肥的可行性。结果表明，餐厨垃圾废水培养的褐球固氮菌在第4~5天活菌数达到最大（Ⅰ类废水3.0×1012 CFU·mL-1，Ⅱ类废水3.3×1012 CFU·mL-1），餐厨垃圾湿热处理对褐球固氮菌生长的促进作用十分有限。废水的pH和盐分对褐球固氮菌的生长代谢影响极为显著：Ⅰ类废水褐球固氮菌生长的最佳pH为7，Ⅱ类废水最佳pH为7.5，其他pH将对褐球固氮菌的生长代谢活性造成不同程度的抑制；随着NaCl含量的增加，固氮菌活菌数先升高后快速降低，最利于菌种培养的NaCl浓度为3 g·L-1。温度、摇床转速和接种量对菌株培养的影响不显著，正交实验确定的较优培养条件为pH=7、T=28℃、转速150 r·min-1、接种量2%（体积分数）。餐厨垃圾废水制备的固氮菌肥可提高土壤总氮水平（线性相关性R2=0.979），施用0.025‰~2.5‰质量比例固氮菌剂的土壤生长的黄豆苗干重可达到按照5‰质量比例施加无机复合肥生长的黄豆苗的55.2%~67.2%。

Preparation of liquid bacterial fertilizer of nitrogen-fixing bacteria from food waste-recycling wastewater

The feasibility of using food waste-recycling wastewater as fermentation substrate for producing liquid Azotobacter chroococcum fertilizer was investigated in this study. The results showed that Azotobacter chroococcum cultured in the food waste-recycling wastewater reached logarithmic growth stage in as short as 3 days of adaptation period, and the number of strains reached the maxima on the 4th to 5th day(wastewater Ⅰ 3.0×1012 CFU·mL-1,wastewater Ⅱ 3.3×1012 CFU·mL-1). The promotion effect of food waste hydrothermal treatment on the growth of Azotobacter chroococcum was very limited. pH and salt concentration of the wastewater had great influence on the growth and metabolism of Azotobacter chroococcum. The optimal pH for Azotobacter chroococcum growth in wastewaterⅠwas pH 7, in wastewaterⅡwas pH 7.5,while other pH would inhibit the growth and metabolism activity of the nitrogen-fixing bacteria. With an increase of NaCl concentration, the strain numbers first increased and then steeply decreased, and the optimal NaCl concentration for bacterial culture was only 3 g·L-1. The variation of temperature, shaking speed and strain inoculation volume affected the growth of Azotobacter chroococcum significantly. The optimal culture conditions were pH=7, T=28℃, shaking speed 150 r·min-1, and inoculums of 2%(volume fraction) as determined by orthogonal experiment. The nitrogen-fixing bacterial fertilizer prepared from food waste-recycling wastewater was able to rise the total nitrogen concentration of soil (linear correlation R2=0.979), and the dry weight of soy beans grown in soils amended with 0.025‰ to 2.5‰ of nitrogen-fixing bacterial fertilizer was from 55.2% to 67.2% of that grown in the soil amended with 5‰ of inorganic fertilizer on weight basis.