Nitrate and bacterial groundwater pollution from dairy farms and surrounding croplands is a large and growing problem not only for surrounding ecosystems, but also for the health of the cattle consuming this untreated water if present at high enough levels. Point-of-use filtration methods could provide a low-cost means of removing such contaminants to within acceptable levels, but experimentation is needed to identify acceptable media and optimal treatment designs.

This thesis is divided into four main chapters; the first chapter presents an introduction to the issue, pollutant health implications, and existing treatment options within a comprehensive literature review. The second chapter aims to assess the prevalence of nitrate and bacteria levels in dairy cattle water troughs throughout several dairy farms in central California. The purpose of the second chapter is to determine whether contaminant levels are within recommended levels as well as to identify the predominant source of each contamination to inform future design aspects of a treatment system. The third chapter aims to assess different commercially available, natural media for their ability to remove nitrate and bacteria through various column filtration and batch adsorption experiments. The fourth chapter outlines preliminary field-scale experiments conducted to assess removal potential at higher flow rates as well as identifies ways to further optimize for contaminant removal.

While there are no set regulations for levels of either pollutant for dairy cattle water consumption, the general recommendation of 44 ppm NO3- was exceeded in 47% of the 62 troughs, and 89% of the 44 troughs analyzed for bacterial levels exceeded the recommended 15 CFU/100 mL total coliform count for adult cattle. These results suggest a significant portion of troughs would benefit from nitrate and bacteria reduction, and when alternative water sources are unavailable, column filtration may provide a sufficient treatment option. Of the filter media tested at lab scale, powdered activated carbon (PAC) provided the highest removal efficiency and adsorption capacity for both contaminants, but the high pressure required as well as its susceptibility to reduced long-term efficiency suggests that multi-media column filtration with PAC may improve the viability for a small-scale cattle drinking water filtration treatment system. Granular activated charcoal (GAC), which has larger particle size and lower surface area was found to achieve the second highest removal rate for both contaminants with lower pressure requirements, so column filtration with mixed media including both PAC and GAC is proposed and tested at field scale. While further optimization is required for the proposed treatment system, it offers a low cost and easily implementable treatment option for improving dairy cattle drinking water in troughs.