Zooplankton-based reactors for tertiary wastewater treatment: A pilot-scale case study

Abstract

Nature-based wastewater treatments are an economic and sustainable alternative to intensive technologies in rural areas, although their efficiency needs to be improved. This study explores technological co-operation between zooplankton (e.g., Daphnia magna) and bacterial and algal biofilms in a 1.5 m3 zooplankton-based reactor for the on-site treatment of secondary urban wastewater. The efficiency of the reactor was evaluated over a 14-month period without any maintenance. The results suggest a low seasonality effect on nutrient polishing (organic matter and nitrogen) and the removal of solids (TSS and turbidity). The best performance, involving a decrease in organic carbon, nitrogen, E. coli loads, and solid content was achieved in winter when operating the reactor at 750 L d−1. Under these conditions, the quality of the effluent water was suitable for its reuse for six different purposes in conformance with Spanish legislation. These results demonstrate that the zooplankton-based reactor presented here can be used as an eco-sustainable tertiary treatment to provide water suitable for reuse. On-site research revealed that the robustness of the reactor against temperature and oxygen fluctuations needs to be improved to ensure good performance throughout the year

The research has been carried out within the INNOQUA project. The INNOQUA project has been funded by the European Commission by the Horizon 2020 research and innovation programme. Our grant agree-ment is No 689817. The authors gratefully acknowledge the support provided by Sorigu ́e S.A.U., which manages the wastewater treatment plant in Quart