Investigation of removal of micro-pollutants in single and dual media biofilters for water reuse | Department of Civil & Environmental Engineering | School of Engineering & Applied Science

Investigation of removal of micro-pollutants in single and dual media biofilters for water reuse (Prof. Riffat)

Biologically active GAC (granular activated carbon) media and ceralite (expanded clay) were used as filter media for this research.

Motivation
The presence of micropollutants in watersheds is of growing concern, especially in drinking water and water reuse systems. Our research focuses on developing state-of-the-art knowledge and processes for removal of micropollutants from water. Our goal is to investigate biofiltration for removal of selected micropollutants. The research focuses on the investigation of fundamental properties of biofilms that are formed on the filter media, as well as pollutant removal mechanisms. Bench scale and pilot scale biofilters were constructed and operated in the Environmental Engineering Laboratory at GW. Three pharmaceutical compounds - acetaminophen, salicylic acid and ibuprofen, were selected as the target micropollutants due to their predominant occurrence in water bodies.

Research Methods
Biologically active GAC (granular activated carbon) media and ceralite (expanded clay) were used as filter media for this research. The GAC media was collected from full-scale biological filters, whereas the ceralite was obtained from the manufacturer. The pilot-scale setup consists of a transparent column (inner diameter of 3 in and height of 3 ft) packed with 1 ft height of filter media (each with GAC and ceralite). Growth of biofilms and removal efficiency of the target compounds were evaluated for both single media and dual media biofilters.

The target micropollutants were measured with GC-MS (Shimatzu QP 2010-SE). The bacterial analysis was conducted with real time PCR (Applied Biosystems QS3). Extracellular polymeric substances (EPS) and ATP were analyzed by heat extraction method and Lumina Ultra test kits, respectively. All other parameters were measured by following the Standard Methods.

Preliminary Research Findings

Ceralite media on top removed Salicylic acid and Ibuprofen in a Ceralite-GAC dual media system.
Acetaminophen was mostly removed by GAC (bottom media).
Substrate removal appeared to be diffusion limited and not biomass limited.
Ozone pretreatment increased the removal efficiency of all micropollutants studied.