National Institute of Water and Atmospheric Research Ltd (NIWA), Aquatic Pollution Group, P.O. Box 11-115, Hamilton, New Zealand.
Water Res. 2011 Dec 15;45(20):6637-49. doi: 10.1016/j.watres.2011.09.042. Epub 2011 Sep 29.
This paper investigates the influence of recycling gravity harvested algae on species dominance and harvest efficiency in wastewater treatment High Rate Algal Ponds (HRAP). Two identical pilot-scale HRAPs were operated over one year either with (HRAP(r)) or without (HRAP(c)) harvested algal biomass recycling. Algae were harvested from the HRAP effluent in algal settling cones (ASCs) and harvest efficiency was compared to settlability in Imhoff cones five times a week. A microscopic image analysis technique was developed to determine relative algal dominance based on biovolume and was conducted once a month. Recycling of harvested algal biomass back to the HRAP(r) maintained the dominance of a single readily settleable algal species (Pediastrum sp.) at >90% over one year (compared to the control with only 53%). Increased dominance of Pediastrum sp. greatly improved the efficiency of algal harvest (annual average of >85% harvest for the HRAP(r) compared with ∼60% for the control). Imhoff cone experiments demonstrated that algal settleability was influenced by both the dominance of Pediastrum sp. and the species composition of remaining algae. Algal biomass recycling increased the average size of Pediastrum sp. colonies by 13-30% by increasing mean cell residence time. These results indicate that recycling gravity harvested algae could be a simple and effective operational strategy to maintain the dominance of readily settleable algal species, and enhance algal harvest by gravity sedimentation.
本文研究了回收重力收获藻类对废水处理高比速藻类塘（HRAP）中物种优势和收获效率的影响。两个相同的中试规模 HRAP 在一年的时间内分别进行了操作，一个是（HRAP(r)），另一个是没有（HRAP(c)）回收收获的藻类生物质。藻类从 HRAP 出水中在藻类沉降锥（ASCs）中收获，并每周五次在 Imhoff 锥中比较收获效率和沉降性。开发了一种基于生物体积的相对藻类优势的微观图像分析技术，并每月进行一次。将收获的藻类生物质回收到 HRAP(r)中，可保持单一易沉降藻类物种（Pediastrum sp.）的优势超过一年（与仅 53%的对照相比）。Pediastrum sp. 的优势增加大大提高了藻类收获的效率（HRAP(r)的年平均收获率超过 85%，而对照约为 60%）。Imhoff 锥实验表明，藻类沉降性既受到 Pediastrum sp. 的优势的影响，也受到剩余藻类的物种组成的影响。藻类生物质回收通过增加平均细胞停留时间，使 Pediastrum sp. 聚集体的平均尺寸增加了 13-30%。这些结果表明，回收重力收获的藻类可以是一种简单而有效的操作策略，以维持易沉降藻类物种的优势，并通过重力沉淀增强藻类收获。
