Precipitating swine manure phosphorous using fine limestone dust

摘要

The effectiveness of fine limestone dust in precipitating swine manure total phosphorous (TP) and total solids (TS) was measured using 3-L volumes and a 1.30 m~3 volume. Respective duplicate limestone samples with particle sizes of 10, 17, 30, 12, 21,and 30 : m, (PULPRO 10, 17, and 30 and SW 12, 21, and 30) were mixed at levels of 0 and 6% into swine manure with a TS and TP of 7.4% and 1210mg/L, respectively. SW 21 was also mixed into the same swine manure at a 2% level. The 1 30 m~3 volume of 8.3%TS swine manure was treated with 6% PULPRO 30. The depth of sludge precipitation was monitored over time and the supernatant and sludge were analyzed for TP, TS, and pH after 12 and 30 days for the 3-L and 1.30 m~3 volumes, respectively. With 2 and 6% SW21, the supernatant liquid was analyzed a second time for TP after 60 days of settling. All limestone particle sizes and dosages performed similarly, by precipitating as much as 96 and 90% of the TP and TS into a sludge equivalent to 53% of the manure volume. Letting the supernatant settle for 60 days rather than 12 days further reduced its TP content by 40%. The 1.30m~3 volume test further demonstrated that the sludge could be pumped despite its TS and density of 22% and 1.07 kg/L, respectively The addition of 2% limestone improved TP and TS precipitation by 4% and greatly improved sludge density and sludge separation from the supernatant.