FIG 6.

Schematic of the experimental setup. Eighty replicate biosand filters (2.54-cm diameter with a 10.5-cm filter bed depth) were constructed from PVC pipes with a standpipe to keep water 4 cm above the sand bed. Daily water inputs were added from either of two water sources (with high or low nutrients), each spiked with diluted wastewater. Samples for DNA extraction, sequencing, and biomass estimation were collected weekly from five replicate filters, including influent, sand, and effluent. Weekly coliform removal was also measured over 8 weeks.