【作者】 迟堃；

【导师】 金文标；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2010， 硕士

【摘要】 我国面临着十分严峻的环境问题:一方面,水污染严重,大量污水得不到处理及合理的资源化利用;另一方面,随着温室效应的加剧,CO₂的减排与固定技术亟待应用。如果能在污水处理系统中构建微藻培养单元,通过将藻细胞从培养系统中分离,从而获得低氮磷含量的出水,在净化污水的同时利用微藻吸收固定CO₂,可以有效实现污水的资源化和CO₂减排的要求。本文通过单因素实验、均匀实验等实验方法,采用人工污水、城市生活污水,考察了影响二形栅藻生长的各环境因素,包括光照、营养物质、pH值、CO₂加富量等。本研究还设置了小试验证试验,在验证先前实验结论的同时,考察了在各种试验条件下藻类对水中污染物的去除情况。本研究得到以下主要研究成果:1)初沉池出水要比二沉池出水更加适合藻类生长,这是由于初沉池出水中的营养物质更加丰富,更加利于藻类吸收。另外初沉池出水中含有较多细菌,细菌与藻类的生长呈现相互促进的作用。2)污水中的微藻能放出大量的活性氧,使得水中溶解氧浓度高达20mg·L^-1以上。但若进行曝气,由于曝气的吹脱作用,最终溶解氧含量就维持在7-9mg·L^-1之间。并且曝气强度越大,溶解氧含量越低。3)加富CO₂对藻类生长有显著的促进作用。加富低浓度的CO₂能有效地增加藻产量,但是加富高浓度的CO₂也会对藻类生长产生抑制。建议采用加富2%(0.004v·v·min^-1)CO₂。4)光照强度与光照周期对藻类的影响存在复杂的交互作用,并且还受到藻液深度,水的透光性等因素的影响。在培养初期,藻液透光性良好,SS对藻类生长的影响并不显著。但是进入稳定期后,藻类生长的最大藻密度会受到水中SS的限制。水中SS越大,藻液能达到的最大藻密度越低。5)尿素作为氮源最利于藻类生长。另外,高浓度的无机氮会对藻类的生长产生抑制作用。在20mg·L^-1～85mg·L^-1范围内,无机氮浓度越高,藻类生长越慢。在典型生活污水磷浓度范围内(2mg·L^-1～8mg·L^-1),磷浓度为4mg·L^-1时最适合藻类生长。pH值对藻类生长的影响十分显著。二形栅藻生长的最佳pH值为7.5。磷浓度与pH值之间无明显交互作用。更多还原

【Abstract】 Environmental problems are very serious in our country: on the one hand, large amount of wastewater discharge in rivers without treatment and reasonable reuse; On the other hand, with the intensification of the greenhouse effect, the reduction CO₂ emission and the application of CO₂ fixing method are in urgent. Once microalgae can be used in wastewater treatment system, it can absorb CO₂ while the purification of wastewater. It is able to effetely achieve wastewater recycling and CO₂ emission reduction requirements.This thesis has used some experiment method （single factor experiment method, uniform experiment method, etc.） to investigate various environmental factors, on the growth of algae in artificial wastewater and real wastewater, including light, nutrients, pH, CO₂ enrichment, etc. This study also set up a laboratory scale experiment, to verify the previous results and investigated the pollutants removal in various experimental conditions.The conclusions of this thesis are as follows:1) The primary sedimentation tank effluent is more suitable for algae growth than the secondary sedimentation tank effluent. Firstly, this is because the primary sedimentation tank effluent enriches more nutrients which are more suitable for algae uptake. Secondly, primary sedimentation tank effluent contains more bacteria, which can promote the growth of the algae.2) Algae can release a large number of active oxygen, which can make the DO up to 20 mg·L^-1. Once aeration, due to aeration stripping effect, the final dissolved oxygen will reduce to 7-9 mg·L^-1. And the greater the aeration intensity, the lower the DO in the solution is.3) The enrichment of CO₂ can facilitate on algal growth significantly. Low concentration enrichment of CO₂ can increase algae production significantly, but high concentrations of CO₂ enrichment will inhibit on algal growth. Recommended enrich 2% (0.004 v·v-1·min^-1) CO₂4) Light intensity and photoperiod have complex interaction effect on algae growth, and also affected by the water depth, light transmission and other factors. In the initial cultivation, because of a good translucent of liquid algae, the effect of SS is not significant on the algae growth. But when the algae grow into the stable period, the maximum cell density will be restricted by the SS concentration. Greater SS concentration is, the lower the maximum cell density can reach.5) Urea as a nitrogen source is the most conducive to algae growth. In addition, high concentrations of inorganic nitrogen inhibit the growth of algae. At 20mg·L^-1 85mg·L^-1 range, the higher the concentration of inorganic nitrogen, the slower growth of algae. In a typical wastewater phosphorus concentration range (2mg·L^-18mg·L^-1), algae grow the fastest when the phosphorus concentration is 4mg·L^-1. pH can significantly affect on the growth of algae. The best pH for Scenedesmus dimorphus growth is 7.5. There is not significant interaction between phosphorus concentration and the pH value.更多还原