Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 10, 2002
Publication Date: November 5, 2002
Citation: DAO, T.H., DANIEL, T.C. 2002. REDUCING PARTICULATE AND DISSOLVED PHOSPHORUS IN DAIRY MANURE SUSPENSIONS. AGRONOMY ABSTRACTS. CD-ROM No 511-DAO170030-P.
In confined animal feeding operations, liquid manure presents special handling and storage challenges because of the large quantity of diluted wastes. The inefficiency of mechanical liquid-solid separators has led to frequent losses of waste storage capacity. Water treatment polymers and phosphorus (P) immobilizing chemicals were used to determine particulate and dissolved reactive P (DRP) reduction mechanisms in high total suspended solid (TSS) dairy manure. Manure TSS had a clear effect on aggregation and chemical doses. Co-application exceeded the level of aggregation achieved with individual amendments. At marginally effective cationic polymer rates between 0.01 and 0.25 g L-1, maximal aggregation was attained in combination with Al2 (SO4)3 (3 and 30 mM Al3+), FeCl3 (3.7 and 37 mM Fe3+), and coal-combustion ash in 30 g L-1 (TSS30) and 100 g L-1 (TSS100) suspensions, respectively. Fly ash destabilized the manure suspensions at rates > 50 g L-1 as mechanistically, ash particles acted as an in situ screen. Also, the ash reduced DRP at rates > 1 g L-1 by 52 and 71% in TSS30 and TSS100 suspensions, respectively. Ash surface functional groups such as ~SiOH and ~XOH reacted with H2PO42- to reduce DRP. Iron and Al salts also lowered DRP at rates < 37 mM but higher concentrations re-dispersed particulates and increased DRP due to increased acidity and EC. We concluded that the synergism of flocculant types allows input reduction in aggregation aid chemicals while enhancing particulate and dissolved P separation and removal in high TSS liquid manure.