I wonder how many social entrepreneurs and community investors it would take to raise enough will and capital to make an algae biodiesel facility that intercepts nitrogen-rich wastewater and grows algae on it. If you can sequester carbon in the process you could make some additional revenue off of the carbon credits. If you had an anaerobic digester you could even harness the methane given off from the algae carcasses as they decompose to make electricity and offset your operational costs. You could likely get municipal organic recycling to contribute.