Biofilters are increasingly being implemented in urban environments to treat stormwater but knowledge on their pathogen removal capacity at field scale is limited. Adequate pathogen removal is, however, needed if treated water is reused. This research evaluates the fate of Escherichia coli, enterococci and Campylobacter in a field scale biofilter in Rotterdam. This biofilter is part of the Urban Waterbuffer Spangen that combines biofiltration with Aquifer Storage and Recovery (ASR) to provide irrigation water for Sparta’s sports field. Microbiological water quality was analysed to assess the removal capacity of the biofilter. To identify factors causing adverse treatment performance, system construction, and operation were investigated, water flows in the biofilter were assessed, and hydraulic conductivity was measured. Lastly, model simulations were used to investigate how short-circuiting and event frequency and duration affect microbiological outflow concentrations. Results showed leaching of enterococci and Campylobacter and minimal retention of Escherichia coli. Leaching is likely caused by secondary contamination with bird faeces and multiple design and operational choices lead to low microbial retention. Coarse filter media results in high hydraulic conductivity, and consequently, short hydraulic retention times. Electrical conductivity measurements revealed short-circuiting pathways between the inlet and outlet. Lastly, uneven distribution of feed water presumably reduced the effective reactor volume. It is recommended to upgrade biofilter design by incorporating small particles in the filter media and maximizing the distance between the inlet and outlet. Additionally, reintroduce a ponding zone and rearranging event frequency and duration to lower microbial outflow loads is advised. Model simulations suggest that short, frequent events are beneficial to control microbial loads. However, further work to clarify microbial decay rates is recommended. To conclude, results imply that the biofilter is currently unable to improve the microbiological water quality but can become a treatment barrier if design and operation are upgraded to tackle encountered problems.

Erosion of the cliffs at the Point Grey Peninsula threatens important infrastructure and buildings at UBC. In order to tackle this problem, UBC launched a comprehensive project called Living Breakwaters. This project is part of Living Breakwaters and aims to act as a transversal element among different expertise, integrating these specializations into a holistic framework. It analyses the problem from a technical, environmental, economic, legislative and social perspective. Four concepts are proposed to tackle the erosion and their key feasibility issues are identified. Accordingly, the main goal of this report is to present a clear and holistic framework of the erosion problem at the Point Grey cliffs, both gathering and integrating existing information and contributing with innovative ideas that might open new approaches for dealing with erosion. In conclusion, the Point Grey cliff erosion is a problem that has to be tackled to prevent severe damage to the adjacent lands. It is advised to combine both marine and subaerial measures. An integrated approach combining technical, environmental, legislative and social expertise is recommended in order to achieve a truly sustainable design.