Mitigate air emissions from animal feeding operations and recover nutrients using an integrated water curtain- Microalgal culture system

Abstract. Air emission mitigation technologies that are both economically and technologically feasible are in high demand to sustain future animal agriculture. In this study, we designed and evaluated an integrated Water Curtain-Microalgal Culture (WCMC) system to mitigate air emissions and reuse nutrients to culture microalgae. The WCMC system included a water curtain, a windbreak wall, and a suspended algae reactor. The water curtain was formed by continuously pumping water into a perforated water tank that flowed into an open raceway microalgal reactor. The exhaust pollutants (NH 3 and particulate matter (PM)) from a poultry house were dissolved or absorbed into the water droplets. Local freshwater microalgae of Desmodesmus (R. Chodata) was screened and isolated from field samples naturally. Desmodesmus showed the best tolerances of temperature, nutrients, pH, and circulation shear force. The microalgal culture in the reactor was run in batch mode. The growth rates were 8.0 g/m 2 /day in batch 1, 15.6 g/m 2 /day in batch 2, 12.6 g/m 2 /day in batch 3, and 9.8 g/m 2 /day in batch 4. Ammonia (NH 3 ) concentrations were reduced by 74.9% by the water curtains. Total suspended particle (TSP) mitigation efficiencies ranged from 75.0% to 95.0%. Carbon dioxide (CO 2 ) concentrations in the outlet air were similar to the concentrations in the inlet air of the water curtains with less than 10% reductions. The adaptation of this new technology will reduce the environmental impact and create a win-win situation for future animal agriculture and microalgal cultivation.