畜禽粪便堆腐过程中有机碳组分与腐熟指标的变化

以牛粪、菌糠、鸡粪等为材料按照两种比例调配为混合基质,在添加或不添加发酵启动剂的条件下在发酵罐中进行为期38 d的堆肥发酵试验,研究4种处理方式下畜禽粪便腐解过程中有机碳及其组分的变化,同时通过综合发芽指数(GI)评判腐解物料的腐熟度,确定GI与有机碳组分的关系.结果表明,添加发酵启动剂可以加速有机物质的降解,使水溶性有机碳和有机酸的含量下降(比初始值含量分别下降了41.85%、85.18%),促进类富里酸向胡敏酸转化,使畜禽粪便达到快速腐熟.在两种物料配比下,较高比例的牛粪不利于堆肥物质的分解和腐熟.根据达到腐熟要求的标准(GI0.8),当TOC357.27 g·kg-1,DOC7.00 g·kg-1,FA6.45 g·kg-1,腐解后期物料的红外光谱在1020 cm-1、1427 cm-1出现较为尖锐的峰值,即碳酸盐和硝酸盐含量增加,且草酸大幅度下降时,可以认为有机物料达到完全腐熟.当牛粪、菌糠、鸡粪的混合体积比为1∶1∶1时,在添加发酵启动剂条件下有机物料在腐解29 d时达到以上腐熟指标.     

投碱种类和氨吹脱对污泥碱性发酵产酸的影响

采用完全混合式厌氧反应器,比较了NaOH和Ca(OH)2 2种碱试剂对污泥厌氧发酵产酸的作用效果,结合氨吹脱作用考察了NH4+浓度的降低对各有机物水解酸化程度的影响.结果表明在pH值为10的条件下,以NaOH调节的体系中各种有机物尤其是挥发性脂肪酸(VFAs)的量明显高于以Ca(OH)2调节的体系.Ca(OH)2调节的体系中释放出的蛋白质有部分沉淀,磷酸盐含量也较低,小于40mg/L;氨吹脱的体系发酵液中氨氮含量减少了43%,增大了VFAs的积累量;在NaOH和氨吹脱的组合条件下,污泥水解酸化程度最好,SCOD为6732mg/L,蛋白质为2029mg/L,碳水化合物374mg/L,VFAs总量2545mg/L,且氨氮含量低于200mg/L;分析认为氨吹脱作用增大VFAs积累量的原因主要是NH4+浓度的减小,促进了产酸菌对于碳水化合物的发酵.     

Biodegradation behavior of agricultural pesticides in anaerobic batch reactors

This study explored the biodegradation potential of two agricultural pesticides (2,4-D and isoproturon) as well as their effect on the performance of the anaerobic digestion process. Three 3.5 L batch reactors were used, having the same initial isoproturon concentration (25 mg/L) and different 2,4-D concentrations (i.e. 0, 100, or 300 mg/L, respectively). All systems were fed with equal amounts of primary sludge and digested sludge and operated at the low mesophilic range (32 ± 2°C). Following an acclimation period of approximately 30 days, complete 2,4-D removal was achieved, whereas isoproturon biodegradation was practically negligible. The presence of 2,4-D did not have a direct effect on acidogenesis since soluble organic carbon [expressed either as volatile fatty acids (VFAs) or as total organic carbon (TOC)] peaked within the first 10 days of operation in all bioreactors. Utilization of VFAs however appeared to follow two distinct patterns: one pattern was represented by acetate and butyrate (i.e. no acid accumulation) while the other was followed by propionate, isobuturate, valerate and isovalerate (i.e. acid accumulation, duration of which was related to the initial 2,4-D concentration). On the whole, all reactors exhibited a successful digestion performance demonstrated by complete VFAs utilization, considerable gas production (containing 45 to 65% methane by volume), substantial volatile suspended solids (VSS) reduction (42 to 50%), as well as pH and alkalinity recovery.