TY - JOUR

T1 - Composting of solids separated from anaerobically digested animal manure

T2 - effect of different bulking agents and mixing ratios on emissions of greenhouse gases and ammonia

AU - Chowdhury, Md Albarune

AU - de Neergaard, Andreas

AU - Jensen, Lars Stoumann

PY - 2014

Y1 - 2014

N2 - We investigated the effects of bulking agents (BA) and mixing ratios on greenhouse gas (GHG) and NH3 emissions from composting digested solids (DS), separated from anaerobically digested manure and other bio-wastes, in small-scale laboratory composters. BA evaluated were plastic tube pieces (PT), woodchips (WC), bio-char (BC), barley straw (BS) and lupin residues (LR) and were included at a DS:BA of 3:1 or 6:1, resulting in nine treatments: CTDS (control, DS only), PT3:1, PT6:1, WC3:1, WC6:1, BC3:1, BC6:1, BS3:1 and LR3:1. Depending on treatment, C losses via CO2 and CH4 emissions accounted for 41.2-65.3gCkg-1 initial total solids (TS) and 4.4-191.7mgCkg-1 TS (8.4-16.1% and 0.001-0.05% of initial total-carbon), respectively, while N losses as N2O and NH3 emissions comprised 2.1-13.6mgNkg-1 TS and 2.7-4.8gNkg-1 TS (0.01-0.04% and 9.1-13.0% of initial total-nitrogen), respectively. Most of the CH4 emissions occurred during the thermophilic temperature phase, which had little or no effect on N2O emissions. BS addition to DS resulted in the lowest cumulative NH3-N and N2O-N losses. BC was as effective as BS in reducing cumulative NH3-N losses, but had non-significant effect on CH4-C emissions. Decreasing the mixing ratio from 6:1 to 3:1 reduced losses of CH4-C and N2O-N (except for BC) without any increase in NH3-N losses. BC and BS proved most effective in reducing emissions of total GHG (as CO2-equivalents). Composting of DS with C-rich BA can thus be an effective means of conserving N in DS, while also reducing GHG emissions.

AB - We investigated the effects of bulking agents (BA) and mixing ratios on greenhouse gas (GHG) and NH3 emissions from composting digested solids (DS), separated from anaerobically digested manure and other bio-wastes, in small-scale laboratory composters. BA evaluated were plastic tube pieces (PT), woodchips (WC), bio-char (BC), barley straw (BS) and lupin residues (LR) and were included at a DS:BA of 3:1 or 6:1, resulting in nine treatments: CTDS (control, DS only), PT3:1, PT6:1, WC3:1, WC6:1, BC3:1, BC6:1, BS3:1 and LR3:1. Depending on treatment, C losses via CO2 and CH4 emissions accounted for 41.2-65.3gCkg-1 initial total solids (TS) and 4.4-191.7mgCkg-1 TS (8.4-16.1% and 0.001-0.05% of initial total-carbon), respectively, while N losses as N2O and NH3 emissions comprised 2.1-13.6mgNkg-1 TS and 2.7-4.8gNkg-1 TS (0.01-0.04% and 9.1-13.0% of initial total-nitrogen), respectively. Most of the CH4 emissions occurred during the thermophilic temperature phase, which had little or no effect on N2O emissions. BS addition to DS resulted in the lowest cumulative NH3-N and N2O-N losses. BC was as effective as BS in reducing cumulative NH3-N losses, but had non-significant effect on CH4-C emissions. Decreasing the mixing ratio from 6:1 to 3:1 reduced losses of CH4-C and N2O-N (except for BC) without any increase in NH3-N losses. BC and BS proved most effective in reducing emissions of total GHG (as CO2-equivalents). Composting of DS with C-rich BA can thus be an effective means of conserving N in DS, while also reducing GHG emissions.

KW - Ammonia

KW - Bulking agent

KW - Composting

KW - Digested solids

KW - Greenhouse gas

U2 - 10.1016/j.biosystemseng.2014.06.003

DO - 10.1016/j.biosystemseng.2014.06.003

M3 - Journal article

AN - SCOPUS:84903135333

VL - 124

SP - 63

EP - 77

JO - Biosystems Engineering

JF - Biosystems Engineering

SN - 1537-5110

ER -