Characteristics of solids produced from coal mine drainage and their suitability for phosphorus control in dairy manure management

Abstract

One strategy to limiting eutrophication in waterways is to reduce the concentration of water-extractable P (WEP) in land-applied manure. In this study, we investigated the feasibility of using mine drainage residuals (MDR), waste solids produced in large quantities from coal mine drainage treatment, to reduce WEP in dairy manure. Twenty MDRs from treatment systems in Pennsylvania were collected and analyzed to determine concentrations of pollutants that may limit land application. Laboratory dose-response tests were conducted using the selected MDRs to determine the effectiveness and kinetics of WEP reduction, and three field-scale MDR application tests were conducted to demonstrate the process of using MDR to decrease manure WEP. The MDR-manure mixtures investigated in this study do not exceed biosolid land application concentration limits set by the USEPA. Amendment rates of 5-10 g MDR L −1 of manure provided significant reductions in WEP. Iron-rich MDR, produced from passive and oxidant treatment of mine drainage, required 1-4 d to reduce WEP to an equilibrium concentration, while Ca-rich materials, produced from lime treatment, required 4-7 d. Three field studies at operating dairy farms confirmed the reduction in WEP when manure was amended with MDR. Unit costs calculated for a 1,900-m 3 manure tank treated with 4.4 g L −1 MDR were US$2.16 per 1,000 L of manure and $30 kg −1 WEP removed. These findings indicate that the WEP of dairy manure is not a fixed chemical parameter and can be modified with amendments such as MDR.

Phosphorus Runoff from Soils Receiving Liquid Dairy and Swine Manures Amended with Mine Drainage Residual

“…The MDRs shown (table 1), all from Pennsylvania coal mines. were chosen from an original 21 candidates by 1) excluding MDRs that exceeded the EPA Title 40-Part 503 Biosolids (EPA Title 40-Part 503, 2018) ceiling limits for any metal (Hedin, 2020), and 2) preferentially selecting MDRs potentially available for future field trials. To avoid potential effects from particle size mixing, each MDR was screened to <1 cm particle size prior to the testing.…”

“…The Brandy Camp and Delmont MDRs (both lime MDRs) which had the highest WEP removal at 8 g L -1 had the lowest at 24 g L -1 . Therefore, because the Brandy Camp MDR was found to contain low levels of elements identified in the EPA Part 503 Biosolids (EPA Title 40-Part 503, 2018) ceiling limits (Hedin, 2020), and because initial dose testing indicated it was effective at reducing WEP (table 1), it was chosen for use in the rainfall experiment with the goal of using a concentration of MDR amendment that would result in a 50% reduction in WEP (Callahan et al, 2002). Also, because decreasing average particle size was shown to have a greater effect on WEP reduction experiments (Hedin, 2020), the MDR used in the rainfall experiments was milled using a Pulva Model B mill to a fine powder (median diameter 25 µm with greater than 96% smaller than 180 µm).…”