National Institute of Water and Atmospheric Research Ltd (NIWA), P. O. Box 11-115, Hamilton, New Zealand.
Water Res. 2013 Sep 1;47(13):4422-32. doi: 10.1016/j.watres.2013.04.001. Epub 2013 Apr 11.
This paper investigates the effect of recycling on biomass energy yield in High Rate Algal Ponds (HRAPs). Two 8 m(3) pilot-scale HRAPs treating primary settled sewage were operated in parallel and monitored over a 2-year period. Volatile suspended solids were measured from both HRAPs and their gravity settlers to determine biomass productivity and harvest efficiency. The energy content of the biomass was also measured. Multiplying biomass productivity and harvest efficiency gives the 'harvestable biomass productivity' and multiplying this by the energy content defines the actual 'biomass energy yield'. In Year 1, algal recycling was implemented in one of the ponds (HRAPr) and improved harvestable biomass productivity by 58% compared with the control (HRAPc) without recycling (HRAPr: 9.2 g/m(2)/d; HRAPc: 5.8 g/m(2)/d). The energy content of the biomass grown in HRAPr, which was dominated by Pediastrun boryanum, was 25% higher than the control HRAPc which contained a mixed culture of 4-5 different algae (HRAPr: 21.5 kJ/g; HRAPc: 18.6 kJ/g). In Year 2, HRAPc was then seeded with the biomass harvested from the P. boryanum dominated HRAPr. This had the effect of shifting algal dominance from 89% Dictyosphaerium sp. (which is poorly-settleable) to over 90% P. boryanum in 5 months. Operation of this pond was then switched to recycling its own harvested biomass, which maintained P. boryanum dominance for the rest of Year 2. This result confirms, for the first time in the literature, that species control is possible for similarly sized co-occurring algal colonies in outdoor HRAP by algal recycling. With regard to the overall improvement in biomass energy yield, which is a critical parameter in the context of algal cultivation for biofuels, the combined improvements that recycling triggered in biomass productivity, harvest efficiency and energy content enhanced the harvested biomass energy yield by 66% (HRAPr: 195 kJ/m(2)/day; HRAPc: 118 kJ/m(2)/day).
本文研究了回收利用对高负荷藻塘（HRAPs）生物质能源产量的影响。两个 8 立方米的中试 HRAPs 平行运行，处理初沉污水，监测时间超过 2 年。从两个 HRAPs 和它们的重力沉降器中测量挥发性悬浮固体，以确定生物质生产力和收获效率。还测量了生物质的能量含量。生物质生产力和收获效率的乘积给出了“可收获生物质生产力”，乘以能量含量则定义了实际的“生物质能源产量”。在第 1 年，在其中一个池塘（HRAPr）中实施了藻类回收，与没有回收的对照（HRAPc）相比，可收获生物质生产力提高了 58%（HRAPr：9.2 g/m2/d；HRAPc：5.8 g/m2/d）。在 HRAPr 中生长的生物质的能量含量更高，HRAPr 中生长的生物质主要由 Pediastrum boryanum 组成，而对照 HRAPc 中则含有 4-5 种不同藻类的混合培养物（HRAPr：21.5 kJ/g；HRAPc：18.6 kJ/g），高出 25%。在第 2 年，将从 P. boryanum 占主导地位的 HRAPr 中收获的生物质播种到 HRAPc 中。这导致藻类优势从难以沉降的 Dictyosphaerium sp.的 89%转变为 5 个月后超过 90%的 P. boryanum。该池塘的运行随后切换到回收其自身收获的生物质，这使 P. boryanum 在第 2 年的剩余时间内保持优势。这一结果首次在文献中证实，通过藻类回收，户外 HRAP 中类似大小的共存藻类群落的物种控制是可能的。就生物质能源产量的整体提高而言，这是藻类培养用于生物燃料的一个关键参数，回收在生物质生产力、收获效率和能量含量方面引发的综合提高，使收获的生物质能源产量提高了 66%（HRAPr：195 kJ/m2/天；HRAPc：118 kJ/m2/天）。
