Particle size and metal distributions in anaerobically digested pig slurry

Abstract

Particle size distribution and trace element patterns were studied in a full-scale anaerobic digestion plant treating pig slurry. Mass balance was established for major (N, P, K, Ca, Fe, Mg and S) and minor (Al, Cu, Mn and Zn) elements. Most of the elements were conserved through the process but part of the P, Ca, Mg and Mn was deposited as crystals lining the digester. In the dry matter of the slurry, Cu and Zn occurred at between 170 and 2600 mg kg(-1) due to pig diet supplements. Analyses of particle size distributions in raw and digested slurries showed a general shift in distribution towards larger sizes due to degradation of small and easily degradable particles as well as formation of large microbial filaments. Graded sieving of digested slurry showed metals to be mainly present on 3-25 microm particles. Less than 2% Cu and Zn was removed by passage through a 250 microm rotary screen.

Effects of Pig Slurry as Basal and Panicle Fertilizer on Trace Element Content and Grain Quality in Direct-Seeding Rice

“…Disposal of animal manure usually involves aerobic composting and anaerobic fermentation [2]. Pig slurry (PS) is primarily used as fertilizer in agricultural production to provide nutrients such as nitrogen (N), phosphorus (P), and potassium (K) to crops [3][4][5][6].…”

Arsenic Transformation in Swine Wastewater with Low-Arsenic Content during Anaerobic Digestion

“…The As removal was carried out by removal of solid forms through MP, as most of the As is associated with the suspended solids [8]. On the other hand, the effects of sampling time on total concentrations of As were obvious, which was caused by the variations in veterinary supplement and drug usage in different months.…”

“…AD process optimizes the conditions (pH, temperature) by separating the acidogenic phase (AP) and methanogenic phase (MP) to enhance the overall degradation efficiency [7]. The AD process influences the accumulation and distribution of heavy metals [8], which is a critical factor in predicting the mobility and eco-toxicity of heavy metals (especially As) [9]. During the AD treatment process, As can be transformed from stable fractions to more bioavailable/toxic fractions with the addition of water and decomposition.…”

Quantitative Determination of Mineral Phases by the X-Ray Powder Diffraction Method in Organo-Mineral Substrates (Digestate, Compost and Ash From Biomass)

“…On the contrary, biogas made from the specifi cally produced agricultural crops contains the lowest amount of potentially hazardous compounds. The organic materials decomposition value during anaerobic fermentation is between 12 and 53% (Marcato et al, 2008;Menardo et al, 2001). The presence of trace elements and heavy metals in turn could legally prevent the use of fermentation residue as fertilizer on agricultural land.…”