Intermittent-vacuum stripping (IVS) was developed as a pretreatment for thermophilic anaerobic digestion (TAD) to improve methanogenesis and hydrolysis activity through preventing free ammonia and hydrogen sulfide (H2S) inhibition from liquid swine manure (LSM). Over 98% of ammonia and 38% organic nitrogen were removed in 60 min from 55 °C to 85 °C with vacuum pressure (from 100.63 ± 3.79 mmHg to 360.91 ± 7.39 mmHg) at initial pH 10.0 by IVS. Thermophilic methanogenesis and hydrolysis activity of pretreated LSM increased 52.25% (from 11.56 ± 1.75% to 17.60 ± 0.49%) in 25 days and 40% (from 10 days to 6 days) in bio-methane potential assay. Over 80% H2S and total nitrogen were removed by IVS assistance, while around 70% nitrogen was recycled as ammonium sulfate. Therefore, IVS-TAD combination could be an effective strategy to improve TAD efficiency, whose elution is more easily utilized in algae cultivation and/or hydroponic system.
Bibliographical noteFunding Information:
This work is supported in part by grants from Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative Citizen Commission on Minnesota Resources (LCCMR), Grants number CON000000055335 and CON000000046824 , and University of Minnesota Center for Biorefining.
- Ammonia inhibition
- Hydrogen sulfide inhibition
- Intermittent-vacuum stripping (IVS)
- Thermophilic anaerobic digestion
- Waste water treatment