Runoff Water: Woodchips Bioreactors
Authors:Jorge Rubalcava, Jorge Rubalcava
Mentor:Monica Palomo, Assistant Professor, California State Polytechnic University Pomona
Los Angeles and San Bernardino Counties utilize man-made channels to transport runoff water to recharge basins. The runoff water carries pollutants that impair water quality. Suspended solids, Fecal coliforn, pH, and turbidity at approximated levels of 5.8 mg/L, 350 cfu/100 mL, 10.1 and 9.3, respectively, have been reported by IEUA and San Bernardino Flood control district. Due to the water quality, recharge basins currently require yearly scouring and maintenance because deposition of suspended particles and algae grow reduces infiltration rates over time.The algae layer is formed from high levels of nitrate in runoff water.
The goal of this research is to develop a low maintenance cost effective system to treat the runoff water before it reaches the basins. Improvement of the water quality will increase the operational life of the basins and reduce maintenance costs. Past research has shown the effectiveness of woodchips to remove nitrate present in water Woodchips were selected because they are readily available, relatively inexpensive, and sustainable to treat water.
Surface water runoff was collected close to the inlet of Chris and Turner basins, both located in Ontario, Ca. Two different contact times were used, 8 hrs and 11 hrs for Turner and Chris, respectively. Samples were taken in the influent and effluent lines and were tested for nitrate concentration. Influent nitrate results from Chris and Turner basins ranged from 5 mg/L to 30 mg/L. Treatment resulted on effluent showing complete or nearly complete removal of nitrate. Removal efficiency increased at higher concentrations. Comparisons of the detention times revealed that the effluent nitrate concentrations have an inverse relationship with the retention time. Our results demonstrate that woodchips bioreactors can be successfully used to improve the quality of runoff water which will be improve recharge operation of both basins.