好氧堆肥对牛粪中典型重金属的钝化作用研究

Study on the passivation effects of typical heavy metals in cattle manure by aerobic composting

为了探讨好氧堆肥工艺降低牛粪中重金属活性、提高牛粪有机肥品质的可能性,试验采用好氧堆肥工艺对牛粪进行发酵,试验期为60 d,于试验开始(第0天)及第3,7,13,20,30,45,60天时测定牛粪中铜(Cu)、锌(Zn)、铅(Pb)、镉(Cd)4种典型重金属含量及其可交换态、还原态、氧化态、残渣态含量,计算不同形态重金属分配率和有效态钝化率,同时测定牛粪温度、pH值、电导率(electrical conductance,EC)、全碳(total carbon,TC)、可溶性有机碳(dissolved organic carbon,COD)、全氮(total nitrogen,TN)、腐殖质(humus)、碳氮比(C/N)理化性质指标,分析重金属钝化率与理化性质指标间的相关性。结果表明:牛粪好氧堆肥过程中Cu、Zn、Pb、Cd含量呈上升趋势,好氧堆肥第60天时,Cu、Zn、Pb、Cd有效态分配率均下降,下降幅度从小到大顺序为Pb<Cd<Zn<Cu;好氧堆肥过程中Cu、Zn、Pb、Cd有效态钝化率均呈现先下降后上升趋势,第60天时有效态钝化率从小到大顺序为Cd<Zn<Pb<Cu;堆体温度在好氧堆肥过程中呈先上升后下降的趋势;堆体pH值和EC在好氧堆肥过程中的变化趋势类似,即整体呈先下降后上升的趋势;堆体TC和DOC含量在好氧堆肥初期快速下降,好氧堆肥第20天后下降速度变缓,第30天后变化不大;堆体TN在好氧堆肥初期波动较大,整体呈上升趋势;腐殖质在整个好氧堆肥过程中含量波动较大,在第0~30天和第30~60天均呈现先下降后上升的趋势;C/N整体呈下降趋势;pH值对Zn和Cd有效态钝化率影响极显著(P<0.01),TC和COD对Cu和Pb有效态钝化率影响极显著(P<0.01)。说明牛粪在好氧堆肥过程中Zn和Cd钝化效果低于Cu和Pb。

In order to explore the possibility of aerobic composting process to reduce the activity of heavy metals in cattle manure and improve the quality of catle manure organic fertilizer,the aerobic composting process was used to ferment cow manure in the experiment.The experiment lasted for 60 days.The contents of copper(Cu),zinc(Zn),lead(Pb)and cadmium(Cd)and their different forms of exchangeable state,reduction state,oxidation state,residual state in cattle dung were determined on the O,3th,7th,13th,20th,30th,45th and 6Oth days of the experiment,and the distribution rate and effective passivation rate of different forms of heavy metals were calculated.Meanwhile,temperature,pH value,electrical conductance(EC),total carbon(TC),dissolved organic carbon(COD),total nitrogen(total nitrogen,COD),humus,and carbon/nitrogen ratio(C/N)of cattle manure were determined,and the correlation between the passivation rate of heavy metals and the physicochemical properties was analyzed.The results showed that the contents of Cu,Zn,Pb and Cd increased during the aerobic composting process.On the 6Oth day of aerobic composting,the available state allocation rates of Cu,Zn,Pb and Cd all decreased,and the decreasing range was Pb<Cd<Zn<Cu.In the aerobic composting process,the available passivation rate of heavy metals decreased first and then increased,and on the 6Oth day,the order of the available passivation rate from small to large was Cd<Zn<Pb<Cu.The temperature of the pile body showed a trend of first increasing and then decreasing during the aerobic composting process.The pH value and EC value in the aerobic composting process showed a similar trend,that is,they decreased first,then increased overall.In the early stage of aerobic composting,the contents of TC and DOC in the pile decreased rapidly,and the decreasing rate became slow afer 2oth day of aerobic composting,and the content did not change much after the 3oth day.In the early stage of aerobic composting,theTN content in the pile fluctuated greatly and showed an overall upward trend.In the whole aerobic composting process,the content of humus fluctuated greatly and showed a trend of first decreasing and then increasing in 0-30th days and 30-60th days.C/N showed a downward trend.The effect of pH value on the available passivation rate of Zn and Cd was highly significant(P<O.O1),and the effect of TC and COD on the available passivation rate of Cu and Pb was highly significant(P<0.01).The results indicated that the passivation effect of Zn and Cd in cattle manure in aerobic compostingwas lowerthan that of Cuand Pb.