Glass Fiber Filters for Manure Water

An especially pungent use for glass fiber filters is described in the latest issue of the Soil Science Society of America Journal. In the paper, “Influence of Dissolved Carbon and Nitrogen on Mineralization of Dilute Liquid Dairy Manure” two scientists from the University of California examined the wastewater used to flush dairy cow waste for the presence of these elements. On dairy farms in which the milk cows are confined, water is used to flush away the manure and is then stored in lagoons to be treated for coarse solids before being re-applied to crop fields through irrigation. Refuse reuse if you will. One problem with this procedure is that if there is too much dissolved Carbon or Nitrogen in the wastewater it can create groundwater contamination. For this study, the researchers collected wastewater samples from seven lagoons and analyzed them in order to investigate the relationship between the starting levels of Nitrogen and Carbon and the wastewater’s mineralization behavior. Their methodology included determinations of Totals Solids (TS) and Total Suspended Solids (TSS) by filtering the manure through a series of glass fiber filters, including the Advantec GF75 (0.3 micron) at several points. The GF75 was also used to filter wastewater samples prior to gravimetric analysis. In this case, the authors found that the amount of Nitrogen that will be mineralized for crop consumption is very likely due to how much dissolved Carbon and Nitrogen is present on denitrification. Further investigation will be needed before scientists can accurately predict how much Nitrogen the crops treated with this water are actually exposed to. The full paper is available here for American Society of Agronomy subscribers.