生物干化餐厨垃圾堆肥腐殖化过程及其腐植酸活性评价

Humification process of bio-dried kitchen waste composting and evaluation of humic acid activity

为探究最佳产率途径,并评价其生化腐植酸的活性,对生物干化餐厨废弃物通过堆肥制备生化腐植酸过程进行研究。以经生物干化初始发酵后的餐厨废弃物为主料,木屑为辅料,设置C/N为25(CN25)、20(CN20)、15(CN15)3组堆肥处理,选取堆肥中腐植酸产率最大的处理,提取腐熟度为50%、80%[即种子发芽指数(GI)为50%、80%]的生化腐植酸,按不同施用浓度[0(Y)、20、40、80 mg·L^(-1)]应用于水培试验,以40 mg·L^(-1)矿源腐植酸为对照(H),通过测定堆肥腐殖化指标及玉米农艺性状指标,探究腐植酸产生规律、最大产率以及该体系的生化腐植酸的生物活性。结果表明:3个堆肥处理均满足基本腐熟要求(GI≥50%),腐殖质、胡敏酸、富里酸含量均呈下降趋势;在堆肥结束时,CN20处理腐殖质含量分别比CN25和CN15处理高155.6%和91.7%,胡敏酸含量分别比CN25和CN15处理高170.3%和98.0%,富里酸含量分别比CN25和CN15处理高150.0%和57.9%,且均达到显著差异水平(P<0.05)。CN20处理的胡富比分别比CN25、CN15高9.0%和23.4%,胡敏酸百分比分别高1.2%和3.1%。低腐熟度(GI-50%)下有最大的腐植酸产率,堆肥腐殖质、胡敏酸、富里酸含量比高腐熟度(GI-80%)高64.3%、57.6%、73.5%。施用浓度为40 mg·L^(-1)时,与矿源腐植酸相比,生化腐植酸显著促进了玉米地上部干质量、株高、叶绿素含量和叶面积、地下部干质量及总根尖数(P<0.05);玉米综合长势顺序依次为GI-50%-20>GI-50%-40>GI-80%-40>GI-50%-80>GI-80%-20>H>GI-80%-80>Y,即施用腐植酸均能促进玉米的生长,其中,施用20 mg·L^(-1)低腐熟度的生化腐植酸对玉米促生效果最佳(P<0.05)。综上所述,调节C/N为20进行堆肥腐植酸产率最大,堆至基本腐熟(GI-50%)时,提取其生化腐植酸以20 mg·L^(-1)施用于玉米促生效果最好、生物活性最高。

This study aimed to examine the process of preparing biochemical humic acid from bio-dried kitchen waste via composting,explore the optimal yield pathway,and evaluate the activity of its biochemical humic acid.The study was conducted by setting up three groups of composting treatments of C/N 25(CN25),20(CN20),and 15(CN15)using kitchen waste after initial fermentation of bio-drying,which was used as the main material and sawdust as the auxiliary material.We selected the treatment with the largest humic acid yield in compost.Biochemical humic acid was extracted with degrees of putrefaction set at 50%and 80%(germination index,GI)with varying application concentrations 0(Y),20,40 mg·L^(-1),and 80 mg·L^(-1).We used 40 mg·L^(-1) mineral humic acid as the control(H)to investigate the pattern of humic acid production through the determination of humification indices.Furthermore,agronomic indicators of maize were applied to the hydroponic test.All three composting treatments met the basic putrefaction requirement(GI≥50%),and the humus,humic acid,and fulvic acid contents showed a decreasing trend.At the end of composting,the humus content of the CN20 treatment was 155.6%and 91.7%higher than that with the CN25 and CN15 treatments,respectively.The content of humic acid observed with the CN20 treatment was 170.3%and 98.0%higher than that with the CN25 and CN15 treatments,respectively.The fulvic acid content observed with the CN20 treatment was 150.0%and 57.9%higher than that with the CN25 and CN15 treatments,respectively.All aforementioned results showed significant differences(P<0.05).The ratio of humic acid to fulvic acid with CN20 was 9.0%and 23.4%higher than that of CN25 and CN15,respectively,and the percentage of humic acid was 1.2%and 3.1%higher than that of CN25 and CN15.Low maturity(GI-50%)was associated with the highest humic acid yield,and humus,humic acid,and fulvic acid contents were 64.3%,57.6%,and 73.5%higher in the compost at low degree of spoilage(GI-50%)than at high degree of spoilage(GI-80%).When applied at a concentration of 40 mg·L^(-1),biochemical humic acid showed significant enhancement of maize shoot dry weight,plant height,chlorophyll content,leaf area,root dry weight,and total root tip number compared to mineral humic acid(P<0.05).The order of maize integrated growth was GI-50%-20>GI 50%-40>GI-80%-40>GI-50%-80>GI-80%-20>H>GI-80%-80>Y.The application of humic acid could promote the growth of maize.The application of biochemical humic acid with a low humic concentration of 20 mg·L^(-1) exhibited the most significant effect on maize growth promotion(P<0.05).Composting with a C/N ratio adjusted to 20 yields the highest humic acid production,especially when subjected to basic decomposition(GI-50%).Extracting biochemical humic acid from this source and applying it to corn at a concentration of 20 mg·L^(-1) results in the most effective promotion of growth with enhanced biological activity.