摘要
为缓解鸡粪厌氧发酵过程中产生的氨氮抑制,采用投加镁磷盐的方式,在厌氧发酵过程中原位脱除氨氮,考察鸟粪石沉淀法脱除氨氮对鸡粪厌氧发酵过程的影响及镁磷盐的利用效率。试验向稳定运行的半连续厌氧反应器内投加MgCl_(2)·6H_(2)O和K_(2)HPO_(4)·3H_(2)O,理论脱除速率为3000 mg/d。第一次加盐脱除氨氮后,试验组反应器内氨氮浓度由2937 mg/L降低至1466 mg/L,平均产甲烷量为0.39 L/g,相较对照组的0.33 L/g提高了18%,镁磷盐利用率为91%;第二次加盐脱除氨氮后,试验组氨氮浓度由2232 mg/L降低至762 mg/L,平均产甲烷量为0.33 L/g,相较对照组的0.30 L/g提高了10%,镁磷盐利用率为90%。研究表明鸟粪石沉淀法能较好的与厌氧发酵过程相耦合,在脱除氨氮缓解抑制的同时,提高系统甲烷产量,并回收部分氮磷资源。
Anaerobic digestion has been widely utilized to dispose of agricultural organic wastes.The renewable energy of methane can be produced during the treatment,together with the digestates rich in the nutrients for the fertilizer.However,the ammonia nitrogen can be tended to accumulate during anaerobic digestion,when using a large proportion of protein-rich substrates,such as chicken manure,pig manure,and kitchen wastes.Once the concentration of ammonia nitrogen reaches over 3000 mg/L in the anaerobic process,the ammonia inhibition is likely to happen,resulting in the decrease of microorganisms’activities and methane production during anaerobic digestion.Struvite precipitation can be a useful way to remove the ammonia nitrogen and phosphorus in the digestates and wastewater.Many studies have been reported to optimize the reaction conditions,such as the molar ratio of Mg to P,pH level,and temperature,to recover the struvite.However,there are only a few studies to combine struvite precipitation with anaerobic digestion.This study aims to investigate the effect of in-situ struvite precipitation on the anaerobic digestion of chicken manure.The MgCl_(2)·6H_(2)O and K_(2)HPO_(4)·3H_(2)O were mixed into the feeding substrate in the stable running reactors for 6-7 consecutive days to remove NH4+-N.The theoretical removal rate was at the speed of 3000 mg/d.Some parameters were detected,including the concentration of ammonia nitrogen,methane yield,total volatile fatty acids(TVFA),and pH during anaerobic digestion.After the first operation of adding MgCl_(2)·6H_(2)O and K_(2)HPO_(4)·3H_(2)O,the concentration of ammonia nitrogen and TVFA were reduced from 2937 to 1466 mg/L,and 2317 to 72 mg/L,respectively,whereas,the methane production was 0.39 L/gVS increased by 18%,compared with the control group(0.33 L/gVS),where the utilization rate of magnesium and phosphate was 91%.After the second operation,the concentration of ammonia nitrogen and TVFA were reduced from 2232 to 762 mg/L,and 2321 to 25 mg/L,respectively,whereas,the methane production was 0.33 L/gVS increased by 10%approximately,compared with the control group(0.30 L/gVS),where the utilization rate of magnesium and phosphorus was 90%.The results demonstrated that the addition of exogenous MgCl_(2)·6H_(2)O and K_(2)HPO_(4)·3H_(2)O greatly contributed to mitigating the ammonia inhibition by struvite precipitation during the anaerobic digestion.An optimum pH was 8.5-9(Li et al,1990)for the struvite precipitation in the nutrient recovery of wastewater.A high utilization rate of magnesium and phosphorus was also achieved,when the pH of the system was 6.9-7.8,due to the high ammonia nitrogen concentration in the system.As such,it can be widely expected to promote the struvite precipitation to consume most of the magnesium phosphate salts.The exogenous MgCl_(2)·6H_(2)O and K_(2)HPO_(4)·3H_(2)O can release H+in the system,when the struvite was formed the lower pH to consume the alkalinity in the digester,easily leading to the acidification of anaerobic digestion.Consequently,the amount of exogenous MgCl_(2)·6H_(2)O and K2HPO4·3H2O needs to be controlled within a reasonable range for the stable anaerobic process.
作者
李博文
朱鸿斌
郭建斌
董仁杰
Li Bowen;Zhu Hongbin;Guo Jianbin;Dong Renjie(College of Engineering,China Agricultural University,Beijing 100083,China;China Huadian Engineering Co.,Ltd.,Beijing 100160,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2021年第22期220-225,共6页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金项目(U20A2086)
中德国际研究培训项目(粮食-饲料-能源玉米生产系统磷资源高效利,328017493/GRK 2366)
中国农业大学2115人才工程资助。
关键词
甲烷
发酵
氨氮
鸟粪石
methane
fermentation
ammonia nitrogen
struvite
