文摘
In order to mitigate the environmental impacts associated with accelerated global N cycle, a hybrid pretreatment procedure combining hydrothermal treatment (HTT) with ammonia stripping was developed to effectively recover N as a valuable ammonia product from chicken manure (CM). Processing of the CM at 180 °C for 30 min resulted in a 208% increase in soluble organic carbon (SOC) and 46% conversion of organic-N to ammonia-N. Analysis of carbon mass balance revealed that carbohydrates, proteins, and volatile fatty acids (VFAs) were the major contributors to SOC (∼100%) in the processed CM under this HTT condition. Further prolongation of holding time to 60 min or increase of HTT temperature to 220 °C resulted in some increase in ammonia yield but obvious decrease in SOC concentration and possible formation of inhibitory or nonbiodegradable products as well, compromising the practical value of the processed CM as feedstock for methane production. After ammonia recovery through a circulating stripping system coupled with acid absorption, methane production potentials of the resultant ammonia-stripped CM residue were assessed via 45 days’ anaerobic digestion trials. Results from this work reflected an overall N recovery efficiency of 57% from CM and increase in methane yield by 24% (compared to those of raw CM).