【作者】 张丽；

【导师】 郑正；

【作者基本信息】 复旦大学 ， 环境工程（专业学位）， 2014， 硕士

【摘要】 随着全球能源短缺、环境污染和温室效应问题的日益严重,发展可再生能源、开发高效的氮磷控制技术以及CO2减排技术必然是大势所趋。而沼气工程的建设正是解决这个问题的有效手段之一。目前,我国沼气事业取得了巨大的成就,但是由于沼气品质较低和产气过程中产生的沼液难以处理,使得大量沼气装置闲置,造成了巨大的能源浪费和经济损失。小球藻作为第一种人工培养的单细胞藻类,分布广泛,生长速度快,营养需求低,吸收污水中的氮、磷能力强。小球藻不仅可以通过光合作用吸收大量的CO2,还可以在异养培养条件下利用有机碳源进行生长和繁殖,这与CO2固定提纯沼气和沼液净化过程相耦合,为沼气提纯和沼液中氮磷的高效去除提供了可能。本论文以沼液培养的小球藻为研究对象,主要对小球藻应用于沼液深度处理和沼气净化进行了基础应用研究。(1)沼液条件对小球藻生长的影响。实验表明：沼液的浓度和酸度会对小球藻的生长产生一定的影响,当沼液的浓度为50%,以及沼液酸碱度为6.5时,小球藻的生长状况最好。因此,利用小球藻处理沼液的时候可以尽可能的接近这种条件。(2)小球藻的不同生长条件对于其去除沼液中营养物质的影响,得出了以下一些结论：(1)不同的微藻接种量、光照强度、光质以及通入空气和CO2等不同条件下,小球藻的生长状况和对沼液营养物质的去除率有很大不同。当选取初始接种藻干重(mg/L)为200时,对总氮总磷有较好的去除效果。(2)光照强度对小球藻去除氮磷的效果顺序是一致的：高光照强度>中等光照强度>低等光照强度,但当光照强度达到饱和后继续增加光照会抑制小球藻的生长,进而影响其处理效率。当光照强度为6000 lux,培养时间7天时,小球藻对总氮总磷的去除效率达到最大,初步得出在净化沼液时小球藻生长的最适光照强度为6000lux。(3)就不同光质而言,当选取了混合波长红：蓝=5：5和7：3时TN去除率相似,都比较高,达到了约75%；在混合波长红：蓝=5：5和3：7时TP去除率大致相同为77%左右。综合氮磷去除效率,混合光质红光：蓝光=5：5时小球藻的氮磷去除率均达到了最大；(4)对于CO2和空气对小球藻氮磷去除率的影响,结果表明通空气和通CO2对沼液中总氮总磷的去除均呈现一个递增的趋势,但是在同一天通1.5%CO2的沼液中总氮的残留量要明显低于与通空气培养的沼液；沼液经过小球藻处理后化学需氧量的去除率达到89.99%。(3)小球藻不同生长条件对沼气净化的影响。实验表明：(1)小球藻对高浓度CO2具有良好的耐受性；小球藻在1.5%CO2下有最好生长,在20%的高浓度CO2中也有良好的生长；(2)小球藻的生物量对CO2去除率的影响表现为起初CO：去除率随小球藻生物量的增加而迅速提高。在小球藻培养至第3天,藻干重为624 mg/L时,CO2的去除率达到最大为68%,之后随小球藻生物量的增加而逐渐降低；(3)当沼液浓度为100%时,最利于小球藻吸收CO2；(4)不同光照强度、光质、CH4浓度影响小球藻去除CO2效率的实验表明,光强60001ux条件下,混合光质红光和蓝光比例为5：5,以及在较低的CH4浓度(45%CH4)条件下,小球藻的CO2去除率最高。在对实验前后沼气净化率进行比较时发现,在实验条件下沼气中CH4含量由原先的60%提升到92.6%。更多还原

【Abstract】 With the problems of global energy, greenhouse effect, the environmental pollution are becoming increasingly serious, it is necessary to develop of efficient renewable energy, develop controlling technology of nitrogen and phosphorus, and CO2 emission reduction technology. While the construction of biogas project is one of the effective means to solve this problem. At present, China’s biogas industry has made great achievements, but duing to lower quality and biogas slurry in the process of producing biogas is difficult to deal with, making a large number of biogas devices idle, resulting in a huge waste of energy and economic losses.Chlorella is a monadic microalgae by the first artificial cultivation. As an ecological widespread and easily cultured microalgae, Chlorella can absorpt of nitrogen, phosphorus stronger in waste water. Chlorella has a rapid growth rate, So abundant CO? can be fixed during photosynthesis, also cultured in the heterotrophic culture using organic carbon sources for growth and reproduction conditions, and combined with CO2 fixation and purification of biogas.This offers the possibility to remove nitrogen/phosphorus of biogas slurry and biogas purification.On the basis of Chlorella cultivation by the culture medium of biogas slurry as the research object in this study, mainly explored chlorella which is applied to profound treatment of biogas slurry and purification of biogas for the basic application research. The research studies three following aspects.First, the influence of biogas slurry conditions on the growth of chlorella. Experimental results show that slurry concentration and acidity to chlorella growth will have some impact, when the concentration of slurry is 50% and the slurry pH of 6.5 up to the best chlorella growth conditions. Therefore, the use of biogas chlorella processing time can be as close to this condition.Second, different growth conditions for its removal of Chlorella slurry of nutrients, reached the following conclusions:(1) Different microalgae inoculum, light intensity, light quality, and pass into the air and CO2 under different conditions, and chlorella growth conditions are very different to the removal of slurry nutrients. When you select the initial inoculation of algae dry weight (mg/L) for the 200, for the removal of TN and TP has a better effect. (2) Light intensity on nitrogen and phosphorus removal effect of Chlorella sequence is the same:high light intensity> moderate light intensity> low light intensity, but when the light intensity reaching saturation continues to increase light will inhibit the growth of Chlorella, thus their efficiency When the light intensity was 6000 lux, cultured for 7 days, chlorella TN and TP removal efficiency is maximized, the preliminary draw optimum light intensity in the growth of Chlorella biogas purification 6000 lux. (3)Different light quality, when mixed wavelength selected Red:Blue=5:5 and 7:3 TN removal similar relatively high, reaching about 75%; mixing wavelength red:blue=5:5 and 3:7 TP removal rate is about 77% about the same. Integrated nitrogen and phosphorus removal efficiency, hybrid optical quality red:blue= 5:5 nitrogen and phosphorus removal chlorella have reached the maximum; (4) For CO2 and air nitrogen and phosphorus removal effect on chlorella, the results showed through the air and through the removal of CO2 slurry of TN and TP are presented in an increasing trend, but pass on the same day in the amount of total nitrogen residual slurry 1.5% CO2 is significantly-lower than the marsh and culture through the air liquid; biogas chlorella treatment after reaching 89.99% chemical oxygen demand removal.Third, chlorella different growth conditions on the impact of biogas purification. Experimental results show:(1) Chlorella has a high concentration of CO2 is well tolerated; Chlorella in 1.5% CO2 under the best growth in high concentrations of CO2 20% also have good growth; (2) Chlorella of biomass of performance for the CO2 removal increased with chlorella biomass rapidly increased. When cultured for 3 days. Chlorella algae dry weight up to 624 mg/L, CO2 removal rate reached a maximum of 68%, followed by biomass with increasing chlorella gradually reduced; (3) When the slurry concentration is 100%, and most conducive chlorella fixed CO2; (4) different light intensity, light quality, CH4 concentration on Chlorella CO? removal efficiency experiments show that light intensity 6000 lux conditions. mixing red and blue light quality ratio of 5:5, and at a lower concentration of CH4 (45% CH4) conditions. the removal of CO2 up to the maximum. At the time of the experiment were compared before and after the biogas purification rate found under the experimental conditions CH4 content in biogas upgrading from the original 60% to 92.6%.更多还原