污泥及其混合堆肥对番茄土壤性质和N_2O排放的影响

目前关于污泥及其生物质堆肥的土地利用过程中土壤性质变化和温室气体排放数据十分缺乏,难以满足农田土壤氮素保存和温室气体减排的需求。该研究通过在番茄种植过程中添加800 kg/hm2新鲜污泥(S-H)、400 kg/hm2新鲜污泥(S-L)、800 kg/hm2秸秆堆肥(VM-S)和800 kg/hm2猪粪堆肥(VM-M),开展土壤性质、无机氮形态、作物生长以及N2O排放特征的研究。结果表明:堆肥处理显著增加了土壤电导率(electric conductivity,EC)(P0.05),其中猪粪堆肥时土壤EC值最大。添加污泥和堆肥都使土壤p H值显著上升(P0.05),最终趋于中性,且VM-M对土壤酸化的抑制效果略优于VM-S。污泥和堆肥处理时土壤NO3--N浓度显著高于对照,且各处理组NO3--N浓度均随时间逐渐下降,NO3--N主要被番茄吸收,部分NO3--N从土壤上层淋溶至下层;NH4+大多数被氧化为NO3-,部分NH4+被植物吸收。在施入的无机氮量相等情况下,VM-M、VM-S、S-H处理组中番茄地上部分生物量分别为1 515、1 383、1 103 g/株,株高分别为56.8、54.5、51.3 cm,对番茄生长的促进效果为VM-MVM-SS-H,而S-H比S-L多施入的氮肥对番茄生长并未起到明显促进作用(P0.05)。与对照相比,污泥或生物质堆肥都显著提高了土壤N2O的排放(P0.05),各处理组N2O的排放均集中于施肥后的前20天,且土壤N2O的排放通量大小顺序为S-L(0.76 kg/(hm2·a))VM-M(0.95 kg/(hm2·a))VM-S(1.19 kg/(hm2·a))S-H(1.71 kg/(hm2·a))。因此,在进行污泥及其生物质堆肥的土地利用时,应考虑有机肥的种类及其施用量,以在提高作物产量的同时改善土壤并减少温室气体排放,在进行污泥的农田利用时可先将污泥与畜禽粪堆肥。     

Influence of sewage sludge and heavy metals on nematodes in an arable soil

Summary The abundance of nematodes was investigated in agricultural plots treated in three different ways, the first with no treatment, the second with 300 m³ ha^-1 a^-1 raw sewage sludge and the third with 300 m³ ha^-1 a^-1 sewage sludge with the addition of heavy metals. The nematodes were determined down to the genus and were assigned to five feeding groups. Total nematode numbers were highest in the site treated with sewage sludge and heavy metals. The smallest total numbers were found in the control site. The plant-feeding nematode genera showed different patterns of abundance depending on the sludge treatment and heavy metal content. For the mycophagic and bacteriophagic nematodes, numbers increased with the amount of sludge, especially in the sites with a higher heavy metal content. The family Rhabditidae was the most numerous group in the sludge plus heavy metals treatment. In contrast to these findings, the omnivorous nematodes were very rare in the sludgetreated plots and were completely absent in plots treated with sludge plus heavy metals, whereas predatory nematodes were numerous only after the application of sludge alone.     

Evaluation of sewage sludge-based compost by FT-IR spectroscopy

The aerobic batch composting fermentations of sewage sludge with wood chips and maturity compost as co-composting additives were carried out in an open type lab-scale reactor. Fourier transform infrared spectroscopy (FT-IR) spectroscopy was used to monitor the composting process, evaluate the degradation rate and thus determine the maturity. Although the composition of the input mixture strongly affects the shape of the infrared (IR) spectra, typical bands of components can be selected and used to follow the composting process.

The appearance, shape and intensity of the nitrate band at 1384 cm^− 1 was well pronounced and evident for a sewage sludge-based compost maturity. An increase of the peak ratio 1384 / 2925 and decrease of 2925 / 1034, 1034 / 1384 correlated with the degree of decomposition. For the composting mixture under study the peak ratios 1034 / 1384 and 1384 / 2925 were more demonstrative. Considering the influence of the composting mixture (components and their ratio) on the shape of the FT-IR spectra the nitrate band at 1384 cm^− 1 can be overlapped by other absorption bands (e.g. lignin bands in 1300–1400 cm^− 1 region) thus appearing in the spectra as a shoulder, and therefore the ratios 1384 / 2925 and 1034 / 1384 become unusable to evaluate the maturity.

FT-IR spectroscopy is a quick and useful method to monitor the composting process; however any particular composting mixture needs preliminary studies of the spectra. Consequently, the most appropriate criteria describing the process (e.g. band ratios, shape and intensity of nitrate band) should be selected and the time / peak ratio curves recorded for a compost mixture under study. Afterwards monitoring of the composting process can be based on the comparison of the controls and definite samples.     

Effect of sewage sludge–coir pith pellets on dry matter yield and trace metal concentration in various plant parts of forage maize

Sewage sludge (SS), a highly heterogeneous semisolid fraction of sewage water (about 1% of the sewage water), contains various amounts of nitrogen (N) and phosphorus (P) as well as trace elements such as cadmium (Cd), lead (Pb), copper (Cu), nickel (Ni) and zinc (Zn) with extremely variable physical and chemical compositions. Application of SS improves soil properties, increases yield and simultaneously increases trace metal content in soil and plants. The difficulty in handling, transporting and applying SS and its adverse effect, especially trace metal content in soil and plant, can be overcome by SS–coir pith pelletization (SSCP) or mixing with sewage sledge–coir pith mixture (SSCM). A study was undertaken to evaluate the prepared SSCM and SSCP (1:1 ratio of SS and coir pith) along with SS on dry matter yield, trace metal content in soil and plant parts. The results showed that increased rates of application of SS or SSCM or SSCP increased the green and dry fodder yield of forage maize. Application of SS as either SSCM or SSCP at 1.2 and 2.4 g pot^?1 significantly reduced the trace metal content diethylene triamine pentaacetic acid (DTPA extractable) in soil and plant parts (leaves steam and root) compared to SS application. Therefore, in order to reduce the bioavailability of trace metal in soil and its uptake by plant, application of SSCM or SSCP at 1.2 or 2.4 g pot^?1 proved to be a better option than SS application.     

Characterization of Dissolved Organic Matter from Sewage Sludge using 3D-Fluorescence Spectroscopy and Chemometric Tools

The aim of the present article is to show the possibilities of chemometric tools and the parallel factor analysis (PARAFAC) model, as well as to understand the complexities of the fluorescence emission-excitation matrix (EEM) of water-soluble organic matter (WSOM) extracted from sewage sludge samples obtained with different origins and stabilization procedures. The variation in the composition of WSOM in the different sewage sludge samples could be correlated with the conditions of stabilization; therefore, the use of fluorescence spectroscopy to monitor these changes can be a useful tool to optimize the management of this residual flux, avoiding environmental pollution. However, the “contour density” EEM maps obtained with fluorescence present continuous spectra with different peaks, valleys, and shoulders where manual peak picking can be complicated and subjective, especially in complex matrixes such as sewage sludge. With the PARAFAC algorithm, it is possible to resolve the emission and excitation spectra of the different fluorescence components present in the samples and their contribution to the total fluorescence. Also, the contribution (scores) of the different fluorophors can be coupled with another chemometric tool to provide an effective classification method using the stabilization conditions of sewage sludge as main criterion. In this study, a wide survey of sewage sludge samples (287) was characterized by fluorescence emission-excitation matrix. The final molecular composition of the sewage sludge samples was not related to the stabilization (aerobic vs anaerobic) treatments. However, a sewage sludge classification based on a combined spectroscopic-chemometric approach was obtained, which could be used for the optimization of sewage sludge use in agriculture, minimizing the environmental risks.     

Sea salmon sludge as fertilizer: effects on a volcanic soil and annual ryegrass yield and quality

Abstract. To evaluate the effect of sea salmon sludge on soil and ryegrass yield and quality, five treatments were tested (30, 60 and 90 t ha⁻¹ of sludge, inorganic fertilizer and control). The sludge contained 16% dry matter (DM), 0.13% total N and 1.6% P. The sludge increased ryegrass DM yield, P and Na content, but decreased K concentrations in soil and plants. Sludge can be applied successfully on to land, but its addition should be complemented with inorganic nutrients (N, K). The high Na content of the sludge may limit repeated application, but the main benefit is its P content.     

Nutrient acquisition and nitrate reductase activity of mycorrhizal Retama sphaerocarpa L. seedlings afforested in an amended semiarid soil under two water regimes

Abstract. We studied the effect of inoculation with three arbuscular-mycorrhizal (AM) fungi ( Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) and Glomus mosseae ([Nicol & Gerd.] Gerd. & Trappe) and the addition of composted sewage sludge on root nitrate reductase (NR, EC 1.6.6.1.) activity, mycorrhizal colonization, plant growth and nutrient uptake in Retama sphaerocarpa L. seedlings afforested in a semiarid, degraded Mediterranean soil under well-watered and non-watered conditions. Six months after planting, the mycorrhizal inoculation and the irrigation of plants had a strong effect on the growth parameters. The effect on plant growth was a negative interaction between plant irrigation and mycorrhizal inoculation and a positive interaction between plant irrigation and composted sewage sludge addition. The latter treatment had a significant, but moderate, effect on the growth but conferred no additional benefit when combined with mycorrhizal inoculation. Mycorrhizal inoculation, composted sewage sludge and irrigation had a significant effect on NR activity in roots and on foliar nutrients. The irrigation significantly increased the positive effect of composted sewage sludge on NR activity and the concentrations of foliar N and K. The effect of mycorrhizal inoculation on NR activity did not depend on the water regime. The effectiveness of mycorrhizal inoculation on the establishment and growth of R. sphaerocarpa seedlings in these Mediterranean conditions was independent of water regime. The addition of composted sewage sludge was only effective when soil water was freely available. The combination of mycorrhizal inoculation and composted sewage sludge addition had no synergistic effect on plant growth.     

污泥对风沙土养分与重金属效应的淋溶模拟研究

[目的]探讨城市生活污泥在沙化林地利用的可行性。[方法]通过室内淋溶模拟试验,研究施用污泥对风沙土养分及重金属含量的影响。[结果]施加污泥模拟淋溶后,风沙土总氮、总磷、速效氮、速效磷在各土层含量显著增加,且0～20 cm土层增幅明显大于20～40、40～60 cm土层;各重金属(Cu、Cr、Pb、Zn)含量在0～20 cm土层增加显著,40～60 cm土层增幅较小。施用污泥淋溶后,风沙土内梅罗指数(0.67)虽低于国家林地土壤质量标准(0.70),短期内未对土壤造成严重污染,但若长期施用污泥,应注意各重金属特别是Cd的累积效应所带来的潜在危害。[结论]城市污泥在沙化林地的短期应用具有较好的可行性。     

污泥施用对土壤及小麦生理特性的影响

以兰州市安宁区污水处理厂污泥为研究对象,采用盆栽方法研究污泥施用后对土壤pH值的影响,对土壤中重金属Cu、Zn、Pb含量的影响以及对小麦叶片叶绿素含量和脯氨酸含量特性的影响。结果表明,污泥施用后土壤的pH值显著下降,并呈递减趋势。不同污泥施加量土壤中3种重金属元素的含量均远低于我国土壤环境质量二级标准(GB15618—1995)中碱性土壤的限制性标准值。3种小麦叶片的叶绿素总含量随污泥浓度的增加而增加,污泥在混配土壤中的干重比为15%时3种小麦均达到最大值,随着污泥施加量的进一步加大出现下降。污泥施用后3种小麦叶绿素a/b值与对照相比无显著变化,小麦叶片中脯氨酸含量比对照有大幅的增加。低污泥施加量时(5%、10%和15%),3种小麦叶片中脯氨酸含量随施加量增加而增加,但高污泥施加量时(25%和35%)的脯氨酸含量无显著增加,污泥中污染物胁迫超过小麦耐受限值后,小麦生理代谢出现反常。土壤中3种重金属元素的含量与3种小麦体内脯氨酸含量均呈极显著正相关关系,土壤的pH值与3种小麦的叶绿素总含量和脯氨酸含量均呈负相关关系。综合考虑污泥施用对小麦生理特性的影响,对小麦的耕种土壤中一次性施用污泥时,污泥在混配土壤中的干重比应限量在15%以下。     

蚯蚓堆肥处理剩余污泥混合有机垃圾的效率研究

为了研究基质堆料高度和高密度接种条件对蚯蚓堆肥处理有机垃圾混合剩余污泥时蚯蚓生物量及其堆肥效率的影响,共设6个处理进行试验,按接种密度-堆料高度表示,分别为:1/10-10cm组、1/10-15cm组、1/15-10cm组、1/15-15cm组、1/20-10cm组、1/20-15cm组。试验结果表明,在堆料高度相同时,蚯蚓生物量与其接种密度呈显著的负相关关系,但接种密度对蚯蚓堆肥效率的影响有限,只有在1/10组同1/15组或1/20组比较时表现出显著差异,而后两个组别之间差异不显著;在接种密度相同时,堆料高度对蚯蚓堆肥效率的影响不显著,而对蚯蚓生物量的影响可能存在一个密度临界点(1/15),在此密度附近,堆料高度对蚯蚓生物量的影响较显著,呈显著正相关关系,而在此密度以上或以下,堆料高度的影响不显著。从产业应用的角度,综合考虑蚯蚓维持种群繁衍的再生产能力以及混合污泥的堆肥效率这两个因素,赤子爱胜蚓(Eisenia foetida)处理有机垃圾混合剩余污泥的最佳接种密度为1/15,堆料高度为15cm。