【作者】 李舟；

【导师】 高宝玉；

【作者基本信息】 山东大学 ， 环境工程， 2014， 博士

【摘要】 大豆蛋白是植物性的完全蛋白质,富含人体所必需的8种氨基酸,几乎与世界粮农组织和卫生组织推荐氨基酸的组成相符,且在营养价值上,可等同于动物蛋白,在基因结构上也最接近于人体氨基酸,是最具营养的植物蛋白质之一[1-2]。我国是大豆生产大国、进口大国和消费大国,据统计,2012年国产大豆用于食品加工行业的超过1000万吨,其中约30%用于大豆蛋白的生产,年产量70多万吨。大豆蛋白加工在我国发展迅速,出口量占世界大豆蛋白总交易量的50%以上[3]。大豆蛋白废水是以大豆为原料经过加工制作大豆分离蛋白所产生的废水,大豆分离蛋白生产工艺主要包括碱溶、酸沉、离心等工序,其中离心段产生大量的乳清废水,是产生污染源的主要环节。大豆分离蛋白简称大豆蛋白,该类废水具有以下特征：(1)废水主要含多聚糖、蛋白质、脂肪酸,另外还有一定量的无机酸和无机盐等,该废水颜色呈乳白色；含较多细小悬浮物,易沉降；大豆蛋白生产废水中的乳清蛋白,其分子量在2000-20000Dt之间,低聚糖分子量在300-700Dt之间。(2)废水温度高、偏酸性,有机物含量高,BOD5/CODcr在0.4以上,易于生物降解；同时,废水中含有足够的N、P等营养物可供微生物生长和繁殖。(3)主要水质指标：p(CODcr)为12000～23000mg/L, p(BOD5)为6000-12000mg/L, p(SS)为2200-7350mgL,p(总氮)为670-1000mgL,pH值为4～5,水温为50-60℃。本论文在查阅大量文献的基础上,并通过调研3家大豆蛋白生产厂家的大豆蛋白废水现有污水处理厂的运行状况,经过综合分析,本研究采用“预处理-UASB-两级A/O-BAF"组合工艺对大豆蛋白废水进行实验,根据实验效果,优选出各个单元的最佳工艺参数,然后将本技术在实际大豆蛋白废水处理厂中应用。实验部分包括预处理实验、"UASB厌氧+A/O好氧”生物处理实验以及曝气生物滤池深度处理实验。第一,预处理实验。大豆蛋白废水预处理的目的是最大限度的去除废水中的悬浮物,同时去除部分有机物,以减轻对后续厌氧生物处理的不利影响。本预处理实验采用混凝气浮,混凝气浮阶段主要研究对大豆蛋白废水中的CODCr、悬浮物(SS)和总氮的去除效果。本研究拟采取“混凝+两级气浮”工艺对大豆蛋白废水进行预处理,并且分别对单独采用混凝沉淀法、“混凝+一级涡凹气浮”以及“混凝+一级涡凹+二级溶气气浮”处理进行了研究。混凝预处理实验在实验室通过烧杯实验进行,混凝剂选择常用的硫酸铝、氯化铁、聚合氯化铝、聚合氯化铁,助凝剂选择阴离子聚丙烯酰胺(PAM)。而气浮实验选择以500L/h小试装置在污水处理厂现场进行;第二,"UASB厌氧+A/O”好氧生物处理实验。厌氧选用UASB厌氧反应器,容积负荷为6.8kgCODCr/m3·d,利用城镇剩余污泥做种泥进行启动,培养出良好的颗粒污泥。好氧实验选择两级A/O工艺,污泥负荷q=0.15kgCODCr/kgMLSSd,污泥浓度MLSS=6000-10000mg/L,污泥龄SRT=20d。厌氧+好氧均以187.5L/h的现场小试形式在污水厂现场进行；第三,BAF深度处理实验。本实验在实验室进行,建立1.6L/h的上向流BAF小型反应装置,通过对不同填料高度、水力停留时间以及气水比的对比实验研究,得出BAF深度处理大豆蛋白废水时的最佳运行参数,最终确定大豆蛋白废水处理达到排放标准。然后,在实验研究的基础上,将“预处理-UASB-两级A/O-BAF"组合工艺应用于实际大豆蛋白生产厂家的废水处理工程实践中。本研究的主要结论如下：(1)大豆蛋白废水的有机物含量较高,为高浓度有机废水,可生化性好,适合采用生物处理技术。本研究在经过查阅大量文献以及对大豆蛋白废水的水质条件进行分析研究的基础上,确定选用以"UASB厌氧+A/O好氧”为主的生物处理技术对大豆蛋白废水进行处理。(2)预处理中试实验中,选用的“混凝一级涡凹气浮+二级溶气气浮”处理工艺可以去除废水中的大部分悬浮物,在进水悬浮物高达4000-5000mg/L的情况下,出水悬浮物为1200mgL左右,解决了废水悬浮物过高给后续厌氧反应器的启动运行带来的消极影响问题。(3)选用城镇污水处理厂的剩余污泥成功接种UASB反应器进行了小试实验,成功培养出性能良好的颗粒污泥,降低了建设投资成本。UASB反应器满负荷正常运行时,容积负荷达到约6.8kgCODCr/(m3-d),CODcr去除率90%右,出水CODcr1000-1200mg/L,处理效果良好。(4)好氧阶段采用两级A/O串联设置、多点布水等设计,整个A/O好氧处理单元对CODcr的去除率达90%以上,氨氮去除率高达93%以上。(5)两级A/O阶段,好氧硝化部分氨氮转化为亚硝酸盐氮,然后回流至缺氧A池反硝化不彻底,导致出水中亚硝酸盐对CODcr浓度有一定的贡献。经过理论、标准溶液和实际水样的实验分析,本研究证实了这一理论,并通过增大回流比、重新分配两级缺氧池的进水比例等措施加强反硝化作用,降低了亚硝酸盐对CODcr的影响。(6)BAF实验表明,将BAF技术应用于大豆蛋白废水的深度处理是可行的,综合考虑运行成本和排放标准,最佳条件为填料高度80cm,水力停留时间4h,气水比15：1。此时的出水CODCr≤60mg/L,BOD5≤20mg/L,氨氮≤5mg/L,悬浮物≤20mg/L,色度≤30。(7)“预处理-UASB-两级A/O-BAF"组合工艺应用于实际的大豆蛋白废水处理实践工程中,系统运行稳定,出水CODcr≤60mg/L,氨氮≤5mgL,悬浮物≤20mgL,达到《山东省海河流域水污染物综合排放标准》(DB37/675—2007)一级标准,污水处理费用约2元/m3。(8)本研究实验部分和实际工程应用均表明,“预处理-UASB-两级A/O-BAF"组合工艺处理大豆蛋白废水,运行成本低,处理效果较好,可以为大豆蛋白废水为代表的高浓度有机废水的处理工程提供理论和实践上的指导,切实解决水污染的防治问题,以实现环境效益、经济效益和社会效益的统一。更多还原

【Abstract】 Soybean protein is plant-based protein, containing8kinds of amino acids,which is almost the same with the recommendation of FAO and WHO. It can be equivalent to animal protein on the nutritional value, the genetic structure of amino acid is most close to the human body, so it is one of the most nutritious plant protein. According to statistics, more than10million tons was used for domestic soybean food processing industries in2012, of which about30%was used in the production of the soybean protein, the annual output was more than70thousand tons. Soy protein processing in our country is developing rapidly, exports accounted for more than50%of the total volume of soybean protein in the world.Soybean protein wastewater (SPW) is produced during the soybean protein processing which mainly includes alkali-solution, acid-isolation, centrifugal process. The centrifugal produces large amounts of whey wastewater, is the main link of pollution sources. This kind of wastewater has the following characteristics:(1)SPW is shown ivory, has high content of organic matter, such as polysaccharide, protein, fatty acids, at the same time, a certain amount of inorganic salts and tiny suspended solids is also contained. The molecular mass of SPW is whey protein2000-20000Dt and oligosaccharide300-700Dt.(2)The other characteristics of SPW are low acidity, high temperature, and great variation is often observed in either composition or flow rate. BODs/CODCr of SPW is higher than0.35.(3) The main water quality indicators of SPW:CODCr:1200023000mg/L,BOD5:6000～12000mg/L,SS:2200～7350mg/L,total nitrogen:670-1000mg/L,pH:4～5, temperature:50-60℃。 Base on consult a great deal of literature and datum and research of Sewage treatment in three Soybean protein production manufacturers.This study adopted combined pretreatment-UASB-Two stage A/O-BAF process to treat SPW.The research included two parts:the experiment and practical application.Firstly, the experiment part:1.In order to reduce organic loading of the subsequent bio-treatments, cavitation-pocket flotation+dissolved air flotation were used for pretreatment in pilot scale experiment (500L/h);2.UASB reactor,which was inoculate by urban sludge,and two stage A/O were selected for the biological treatment in lab-scale test (187.5L/h);3. In order to achieve discharge standard, chose BAF for advanced wastewater treatment in lab-scale test. Secondly, combined pretreatment-UASB-Two stage A/O-BAF process was applied in the practical wastewater treatment of soybean protein production factory. The main conclusions were summarized as follows:1.SPW contains high amount of organic matters,and BODs/CODcr of SPW is higher than0.35. Therefore, biological technology is suitable for SPW treatment. Based on comprehensive analysis of numerous literatures, biological treatment technology mainly composed of UASB and A/O was adopted in SPW treatment.2. Cavitation-pocket flotation and dissolved air flotation could remove most of SS in pretreatment. The effluent SS was1200mg/L,while the influent was4000-5000mg/L.Tt reduced this influence of high SS to anaerobic treatment.3. Well performing granular sludge was cultivated by inoculation with urban sludge in UASB. UASB achieved good processing effect with volume load of6.8kgCODCr/(m3·d), CODCr removal rate of90%.4.Both of CODcr and NH3-N removal rate was higher than90%in two stage A/O for aerobic treatment. 5.Part of ammonia was converted to nitrite nitrogen, and nitrite nitrogen would influence effluent CODcr,if denitrification was not complete.Through the research of principle and experiment, this study verified the theory of the influence of nitrite nitrogen for CODcr·6.The result of BAF experiment showed that it was feasible to use BAF for advanced treatment of SPW. The optimum conditions were media height of80cm, HRT of4h, and A/L of15:1, meanwhile, water quality discharged were CODcr^60mg/L, BOD5≤20mg/L, ammonia nitrogen≤5mg/L, SS≤20mg/L, chromaticity≤30.7. The systerm of pretreatment-UASB-two stage A/O-BAF process worded well in practical application, the indicators of effluent was lower than the limits of the discharge standards of Shandong Province (CODcr≤60mg/L, BOD5≤20mg/L, ammonia nitrogen≤5mg/L, SS≤20mg/L,chromaticity≤30).8.The results of both experiments and practical application of pretreatment-UASB-two stage A/O-BAF indicated the technology achieved very good processing effect with Low cost.Tt could provide guidance for the theory and practice of SPW treatment.更多还原