ABSTRACT

Over the last 15 years, New Zealand led research on wastewater treatment high rate algal ponds (HRAP) has focused on ways to optimise pond performance, particularly with respect to nutrient removal and resource recovery (microalgal biomass production). The primary motivation for most of this research has been the need to cost-effectively improve wastewater treatment, particularly in small towns and rural communities, where wastewater treatment would otherwise be unaffordable. The ability to recover resources (water and nutrients) helps enable a circular bio-economy, through the reuse of these recovered resources in future products. New Zealand HRAP research has focused on 10 broad categories, including improving pond performance (nutrient removal and biomass yield), environmental impacts of HRAPs, pond design and operation, microalgal and zooplankton community composition and control, algal-based products, enhancing phosphorus removal, biomass harvesting and emerging contaminants. Research has been carried out at a range of scales, including mesocosm, pilot-scale and full-scale. Simple modification to how HRAPs are operated, such as culture depth, operating ponds in series, biomass recycling and night-time CO₂ addition, have been shown to improve pond performance, particularly nutrient removal, biomass productivity, species dominance maintenance or zooplankton graze control. However, despite our improved understandings over the last 15 years, there are still a number of priorities for increasing HRAP performance, including effective CO₂ addition at full-scale, improving phosphorus removal and reducing potential environmental impacts of HRAPs. Uptake of HRAP technology by local government bodies and industries is low and the reasons for this are not fully clear. Cost-effective and sustainable harvesting of the microalgal/bacterial biomass, to ensure effluent discharge meets total nutrient and total suspended solids load limits, is one barrier that must be overcome to allow greater uptake of this technology.

摘要

在过去的15年中，新西兰领导的废水处理高速率藻类池塘（HRAP）研究集中于优化池塘性能的方法，特别是在营养去除和资源回收（微藻类生物质生产）方面。大部分研究的主要动机是必须有成本效益地改善废水处理，尤其是在小城镇和农村社区，否则废水处理将无法承受。回收资源（水和养分）的能力通过在未来产品中重复使用这些回收的资源，有助于实现循环生物经济。新西兰的HRAP研究集中于10个大类，包括改善池塘性能（营养物质去除和生物量产量），HRAP对环境的影响，池塘的设计和运营，微藻和浮游动物群落组成和控制，以藻类为基础的产品，可增强除磷，生物量的收集和新出现的污染物。已经在各种规模上进行了研究，包括中观，中试和全面。简单修改HRAP的操作方式，例如养殖深度，串联操作的池塘，生物质循环利用和夜间CO₂此外，已显示改善池塘的性能，特别是改善养分去除，生物量生产力，物种优势维持或浮游动物放牧控制。但是，尽管在过去15年中我们对理解的了解有所提高，但提高HRAP绩效仍然有许多优先事项，包括有效的CO ₂全面添加，可改善除磷效果并减少HRAP的潜在环境影响。地方政府机构和行业对HRAP技术的采用率很低，其原因尚不完全清楚。微藻/细菌生物质的经济有效且可持续的收获，以确保废水排放满足总养分和总悬浮固体负荷限制，是必须克服的障碍之一，以允许更多地采用该技术。