【作者】 时敏；

【导师】 廖安平；

【作者基本信息】 广西民族大学 ， 生物化学与分子生物学， 2012， 硕士

【摘要】 随着木薯加工行业的飞速发展和市场对木薯产品需求的不断增加，木薯在带动地方经济的同时，也带来了一定的环境污染。其中，木薯淀粉生产过程中的木薯淀粉废水是木薯加工行业的主要污染。由于悬浮物浓度高，有机污染物浓度高，pH低，负荷变化大（即水质和水量变化大）等特性，加上木薯淀粉废水产生的不连续性，给污水的治理带来了较大的困难。目前，国内大多数淀粉厂采用传统的生化法对木薯淀粉废水进行处理，处理效果往往不好，达不到排放标准；少数用先进工艺的厂家，有了一定的效果，但没有对废水进行资源化利用，浪费了大量资源。本文采用生物好氧法对木薯淀粉废水进行处理，利用微生物之间的协同作用，多菌发酵生产单细胞蛋白（SCP）。通过对微波快速消解法的校正、木薯淀粉废水的表征、高产淀粉酶和纤维素酶的菌株及SCP生产菌株的筛选、单菌发酵条件的优化、多菌发酵条件的优化及正交试验确定最佳发酵工艺的研究，一方面提高微生物对木薯淀粉中有机污染物的降解能力，达到废水净化的目的，另一方面，提高SCP菌体的产量，收集加工作为饲料蛋白，达到对废水资源化利用的目的。实验结果表明：（1）加样量为4mL，掩蔽剂加入量为0.10g每毫升废水，消解罐摆放在转盘的外同心圆时，微波密闭快速消解法的COD_Cr测定结果最接近回流重铬酸钾法测定结果。（2）木薯淀粉废水pH在3.80⁴.30之间，蛋白质含量在1.11g/L¹.23g/L之间，还原糖的含量在0.62g/L⁰.66g/L之间，固形物含量约为8.01g/L，SS量约为4.86d/L，废水的总COD_Cr值为12744.7mg/L，总BOD5值为7896.6mg/L。（3）还原糖含量的跟踪测定表明黑曲霉是最佳的产淀粉酶和纤维素酶菌株；总蛋白含量的测定表明，热带假丝酵母是最佳的生产SCP菌株。（4）多菌发酵的单因素确定实验可知，优化后接种量为6%、装液量为130mL、酵母菌接种时间为黑曲霉发酵后20h、发酵初始pH5、发酵温度为29℃和发酵转速为175rpm。（5）当条件为接种量为8%，酵母菌接种时间为黑曲霉接种后第20h，装液量为130mL，初始pH4.5，发酵温度为29℃，发酵转速为200rpm。COD_Cr去除率为96.2%，SCP获取量为16.16g/L。更多还原

【Abstract】 With the increasing demand for cassava products and the rapid development of cassava processing industry, cassava processing industry stimulates the local economic development but also brings a certain degree of environmental pollution at the same time. Cassava starch wastewater comeing from cassava starch production process is the major pollution of the cassava processing industry currently. Cassava starch wastewater’s treatment is very difficult, because of its characteristics of high suspended solids concentration, high organic pollutants concentration, low pH and large load changes (water quality and quantity changes), together with the discontinuity of cassava starch wastewater’s producing. Currently, most starch factories are using traditional biochemical methods to process cassava starch wastewater, and the disposal results are often not good enough according to the emission standards; few facturies process wastewater with advanced technique which achieve better disposal effect, but the resource utilization is not adopted in these wastewater disposal process, which results in resources waste.This study applied aerobic biological method on cassava starch wastewater treatment, and single cell protein (SCP) was produced by mixed-culture fermentation through the microbial synergies at the same time. The study was carried on by correcting of microwave digestion method, characterizing of cassava starch wastewater, screening for strains with high amylase and cellulase production ability, screening for strains with high SCP production ability, optimizing conditions on single-strain fermentation, optimizing conditions on mixed-culture fermentation, and determining the optimal fermentation technique by orthogonal test. It showed that diposal method in the study could improve the microbia’s degradation ability for organic pollutant in cassava starch wastewater, which help cleaning wastewater more efficiently, secondly, the method could improve production of SCP which coulld be collected and used as feeding-protein, then the aim of wastewater resources utilization was achieved. The experimental results indicated that:(1) The CODcr outcome of microwave airtight fast digestion method approached mostly to the method of potassium dichromate reflux under the condition of:the amounts of waste water samples was4mL, the amounts of masking agent was1g/L, and the microwave digestion cans was put around the outer circle of the template.(2)The pH of cassava starch wastewater3.80～4.30, it contains1.11g/L～1.23g/L protein and0.62g/L～0.66g/L reducing sugar,8.01g/L soluble solid content, the CODcr and BOD5in the waste water are12744.7mg/L and7896.6mg/L separately。(3) It is showed that Aspergillus niger is suitable strain for starch and cellulose degradation by tracking and analysing the reducing sugar content, and Candida tropicalis is suitable strain for SCP production by analysing the protein content.(4) The single factor experiments show that the optimal conditions in mix culture fermentation as follow:6%inoculating quantity,130mL medium, inoculation for20h, initial fermentation pH at5, culture temperature at29℃and rotation at175rpm。(5) The removal rate of CODcr is96.2%with16.16g/L SCP harvest under the condition:8%inoculating quantity,130mL medium, inoculating yeast20h after A. niger’s inoculation, initial pH4.5, culture temperature at29℃, rotation at200rpm.更多还原