温室内密闭小环境降温除湿效果及蒸腾水循环利用

为探索密闭小环境对其内部温湿度及蒸腾水循环利用的影响,该研究对温室内盆栽做全密闭处理,基于“温差”热交换原理,通过调控盆栽小环境内的温湿度,降温除湿的同时回收利用蒸腾水。结果表明,利用“水-气温差”对密闭盆栽进行降温除湿回收蒸腾水,降温除湿效果显著,正午12:30左右,相比密闭对照盆栽,温度降低3℃左右,相对湿度下降7%;其他时间降温除湿效果虽不及正午,但白天平均降温2.4℃,相对湿度平均下降5%,蒸腾水最终都回收到U型管中。而利用“地-气温差”进行热交换、利用气泵使水汽循环,对密闭盆栽进行降温除湿回收利用蒸腾水。试验过程中,夜晚的降温除湿效果不显著。白天气泵运行期间,地-气热交换处理盆栽相对于密闭对照盆栽温度平均下降2.5℃左右;相对湿度平均下降10%。正午时分,降温除湿效果最为显著,相比密闭对照盆栽气温降5℃以上,与温室内的温差只有1.5℃;此时湿度下降15%。降温后凝结而成的水珠在高速气流的带动下重复利用于盆栽。由此可见,利用水-气、 地-气温差对密闭盆栽小环境可实现降温、除湿并实现蒸腾水的回收利用。     

石油污染土壤的生态风险评价和生物修复 Ⅳ.油泥的预制床修复及其微生物群落变化

通过添加有机肥、调理剂、接种烃降解菌以及搭建温室等方式对某油田的含油污泥进行了大规模的预制床生物修复。结果表明,经过230d的修复,不同修复处理油泥中的油和脂含量降低了27.5%～46.3%,其中处理RCPG(有机肥+调理剂+接种烃降解菌+温室)的修复效率最高,而在对照中仅为15.1%。经统计分析,在所有处理措施中添加有机肥、调理剂以及搭建温室对修复效率具有显著影响(p0.05),而投加菌剂效果不显著。生物修复措施在降低油泥中污染物含量的同时也改善了油泥的理化性质,使氮、磷等营养物含量及田间持水率显著升高。同时结果还表明,所有修复处理油泥中的烃降解菌数量、微生物活性与多样性与对照相比均有极显著增加(p0.01)。     

过磷酸钙和双氰胺联用减少污泥堆肥温室气体及NH3排放

为研究添加剂过磷酸钙和硝化抑制剂双氰胺联用对脱水污泥高温好氧堆肥氨气和温室气体减排的影响效果,该文以脱水污泥和玉米秸秆为原材料,设置4个堆肥处理分别为:不添加任何添加剂作为对照(CK),只添加3.5%(湿基)过磷酸钙为SP3.5,在添加0.1%双氰胺基础上分别加入3.5%(湿基)过磷酸钙(SD3.5)和5.0%(湿基)过磷酸钙(SD5.0)控制材料,在60 L发酵罐中进行为期34 d好氧高温堆肥试验,监测堆肥过程中的温室气体、氨气排放速率及堆体总有机碳和总氮损失率。结果表明:添加过磷酸钙及硝化抑制剂双氰胺可以促进堆肥腐熟和提高堆肥品质,同时降低堆肥过程中的总氮损失、NH_3排放以及显著减少污泥堆肥总温室气体排放。2种添加剂联合使用使SD3.5和SD5.0处理氮素损失相比于CK处理减少10.92%和13.08%,总温室气体排放量比对照减少65.6%和74.8%。该研究可为污泥堆肥添加剂的选择以及污染气体的减排控制提供参考。     

塑料棚茶园内外温湿度的相关性分析

对塑料棚茶园内外日平均气温、１４时平均气温、最低气温和平均空气相对湿度、最小空气相对湿度之间的相关关系进行了统计分析和曲线拟合，建立了相应的回归方程，利用该组方程式，可计算和分析拱塑料棚内茶园的增温、增湿和抗寒效应。     

密闭温室半导体制冷除湿及蒸散水回收灌溉装置的研制

为了提高人工补光温室的水分的利用效率低下的问题,该文以盆栽辣椒为研究对象,在密闭温室中试验种植,采用半导体制冷热交换和空气露点除湿的方法,对辣椒在发育期、开花期和结果期的蒸散水回收效率进行研究,对比自然对流和强制对流方式除湿的效果以及温室内外盆栽辣椒的生长情况。结果表明:冷凝板温度最低达5.5℃,满足露点除湿条件。在盆栽辣椒的不同生长时期,强制对流进风方式下的室内温度变化范围为18.6~28.2℃,室内湿度变化范围为41%~61.7%,除湿效果随温度升高而显著提高;日回收量从35 m L增加到375 m L,日灌溉量从132 m L增加到540 m L,蒸散水回收率最高达69.4%。密闭温室中盆栽辣椒能够正常生长,而室外盆栽辣椒生长受到抑制。人工补光密闭温室系统除湿效果明显,有效的利用回收水进行盆栽辣椒灌溉。结果表明,人工光密闭温室内半导制冷除湿和蒸散水回收的研究对提高温室作物水分利用效率有积极的推动作用。     

恒温下相对湿度对果蔬热风干燥特性和品质的影响及调控

相对湿度作为干燥介质的重要参数,对干燥热质传质过程和干燥品质具有显著影响。但由于相对湿度对干燥过程的影响机理及优化调控机制尚不明确,导致相对湿度的调控方式多依靠经验,造成干燥效率低、品质差、能耗高等问题。对于传质过程,降低相对湿度能够增大对流传质系数,加快物料表面水分蒸发;而对于传热过程,升高相对湿度能够增大对流传热系数,加快物料升温速率。相对湿度较高时,物料升温速率快,内部水分迁移量增大,但表面水分蒸发量较小;而当相对湿度较低时,物料升温速率较慢,内部水分迁移量较小,但表面水分蒸发量较大。相对传热和传质过程的影响此消彼长,互相耦合。高相对湿度主要体现为对传热过程的影响,低相对湿度主要体现为对传质过程的影响。高相对湿度能够抑制物料表面的结壳,并能够提高复水性,降低收缩率。阶段降湿及多阶段降湿干燥方式下物料表面形成和保持了蜂窝状多孔结构,能够提高干燥效率和品质。基于监测物料温度的相对湿度调控方式被验证为较忧的相对湿度控制方式。阶段降湿干燥方式适用性的实质为：干燥过程中所体现出的对流传热热阻和内部导热热阻的相对大小,及对流传质阻力和内部传质阻力的相对大小,不同干燥条件和物料种类、厚度会影响以上传热传质阻力的大小,从而呈现出不同适应性的结果。当阶段降湿干燥过程中传热毕渥数>1且传热毕渥数>0.1时,说明阶段降湿干燥过程适用于此物料的干燥。该文综合论述了相对湿度对果蔬热风干燥过程中热质传递及干燥品质的影响,优化调控策略及适用性范围4个方面内容,明确了果蔬热风干燥过程中相对湿度的影响机理,为相对湿度的优化调控提供理论依据和技术支持。     

连栋塑料大棚内温湿度及番茄叶片净光合速率的垂直和水平分布特征

为探索连栋塑料大棚内气候因子的变化特征,对温室内垂直方向和水平方向的气温和相对湿度进行了连续的观测,结果表明,不同天气条件下温室内平均气温和平均相对湿度具有明显的变化特征。番茄叶片净光合速率的梯度分布特征是上部最大,中下部则迅速下降。     

Venlo型温室外遮阳和屋顶喷淋系统夏季降温效果

该文对荷兰Venlo型连栋温室夏季采用自然通风并结合遮阳网、室外屋顶喷淋的降温效果进行了实验研究。实验中对温室内空气温、湿度,太阳辐照度进行了测试,以比较外遮阳和屋顶喷淋的降温效果。结果表明:Venlo型温室夏季采用自然通风结合外遮阳和屋顶喷淋的降温措施后能够有效降低室内温度。不同于其它蒸发降温系统,屋顶喷淋没有造成温室内湿度的显著增加,室内的温度和湿度分布比较均匀。这种降温措施的能耗小,可以达到温室降温和降低温室夏季生产成本的双重目的     

连栋塑料大棚内温湿度及番茄叶片净光合速率的垂直和水平分布特征

为探索连栋塑料大棚内气候因子的变化特征，对温室内垂直方向和水平方向的气温和相对湿度进行了连续的观测，结果表明，不同天气条件下温室内平均气温和平均相对湿度具有明显的变化特征。番茄叶片净光合速率的梯度分布特征是上部最大，中下部则迅速下降。     

南方温室内空气循环式蓄热除湿系统的冷凝、蓄热与除湿效应

根据2003年1月、2月的相关观测资料,研究了冷凝温室内空气循环式蓄热除湿系统的冷凝、蓄热与除湿效应。结果表明：冷凝温室在2003年1月的晴天里,集水池平均每天蓄积冷凝水76810m^3,折合温室产生冷凝水量32g／m^2和12．1g／m^3;平均每天冷凝水吸收的汽化热为18858kJ。在典型晴天,冷凝温室下、中、上各层的日平均相对湿度分别比对照温室降低2．7个百分点、3．5个百分点、2．6个百分点,日平均绝对湿度分别比对照温室降低2．7g／m^3、4．1g／m^3、4．5g／m^3;在1月份,2座温室内同日同层次的相对湿度与绝对湿度,均呈现出冷凝〈对照,但以晴天差异尤为明显,阴雨天差异较小。空气循环式温室蓄热除湿系统的冷凝、蓄热、除湿效果明显。     

Effects of thermal drying on phosphorus availability from iron‐precipitated sewage sludge

Thermal drying of sewage sludge implies sanitation and improves practical handling options of the sludge prior to land application. However, it may also affect its value as a fertilizer. The objective of this study was to assess whether thermal drying of sewage sludge, as well as drying temperature, affects plant P availability after application to soil. The experiment included dewatered sewage sludge (20% DM) and thermally dried sewage sludge (95% DM) collected at a Danish wastewater treatment plant, as well as laboratory oven‐dried (70, 130, 190, and 250°C; DM > 95%) subsamples of the dewatered sludge, and a triple superphosphate as a reference. Plant P availability was studied in a 197 d soil incubation experiment, with sampling for Diffusive Gradients in Thin films (DGT) and water extractable P (WEP) analyses over time, and in a pot experiment with spring barley (Hordeum vulgare L.). In both experiments, thermal drying reduced P availability, as shown by 37 and 23% lower DGT and WEP values, respectively, and a 16% lower P uptake by barley in the pot experiment. The specific drying temperature did not appear to have much effect. Overall, our results suggest that thermal drying of iron‐precipitated sewage sludge is not an optimal treatment option if the aim is to optimize plant P availability.     

污泥低温干燥动力学特性及干燥参数优化

为了研究污泥的低温干燥动力学特性,以薄层污泥为研究对象进行了低温干燥试验,探讨了温度、薄层厚度以及风速对污泥水分比和干燥速率的影响,并对低温干燥参数进行了优化.结果表明:污泥低温干燥过程主要由升速和降速段组成,其中降速阶段存在第一、第二降速阶段;不同低温干燥条件下的第二临界含水率变化不大,大致在0.5g/g(干基)附近.使用决定系数R2、卡方χ2及均方根误差RMSE对6种常用干燥模型进行评价,结果表明Midilli模型的平均R2最大、平均χ2及RMSE最小,分别为0.9998、2.46×10-5、0.0042,是描述污泥低温热风干燥的最优模型.根据Fick第二定律和Arrhenius方程,得到5、10和15mm厚度污泥在50~90℃热风干燥的水分有效扩散系数和活化能.正交试验得到相对单位能耗最优干燥工艺为:温度90℃、风速0.8m/s、厚度10mm,平均干燥强度最优工艺为干燥温度90℃、风速0.8m/s、厚度5mm.试验结果可为后续研究污泥热泵干燥及太阳能-热泵联合干燥提供参考.     

污泥堆肥对矿区复垦土壤栽培基质保水能力的影响

污泥堆肥可以有效地用作土壤改良剂和肥料,通过温室盆栽文冠果试验,研究了复垦土壤添加污泥堆肥对复垦植被生长量及土壤含水量和凋萎点的影响.结果表明,污泥堆肥不仅可以促进文冠果的生长,而且可以增强栽培基质的保水性能和植物的抗旱能力.但是,污泥堆肥的用量并不是越多越好,当其用量超过60%时,继续增加污泥堆肥的比例,则植物的吸水能力反而会下降.可见,采用经过堆肥化处理的污泥作为矿区复垦植物栽培基质是可行的无害化途径.     

A scanning electron microscopy study of the interactions between sludge organic components and clay particles

Scanning electron microscopy was used to observe the effects of the addition of water-extracted components from sewage sludge on the fabric of kaolinite and montmorillonite saturated with Na or Ca. The SEM micrographs showed that organic components of the sludge bind the clay particles together and promote microaggregation. Possible binding mechanisms include bridge formation by organic fibers as well as coating and envelopment of the clay particles by organic substances. Application of a drying and wetting cycle to a Ca-montmorillonite/sludge mixture enhanced irreversible aggregation of the material. The organo-mineral interactions observed here for pure clays may shed light on the mechanisms involved in the stabilization of soil structure due to sludge disposal.     

Plant availability of phosphorus from dewatered sewage sludge,untreated incineration ashes,and other products recovered from a wastewater treatment system

The objective of the present study was to evaluate the plant phosphorus (P) availability of products derived from new P‐recovery technologies deployed in wastewater treatment systems against sewage sludge and untreated sewage sludge ashes. Eight P sources were evaluated in a six‐week pot experiment with spring barley (Hordeum vulgare L.) and a soil incubation experiment with anaerobically digested and dewatered sewage sludge (Sludge), sewage sludge ash (Ash), thermochemically treated sewage sludge ash (TrAsh), struvite (Struv), concentrate (Conc), and centrifuged concentrate (Prec) from evaporated reject water, with triple super phosphate (TSP), and composted organic household waste (Comp) as references. All sludge‐related materials except struvite came from the same wastewater treatment plant in Denmark. The apparent plant P use efficiency (PUE) of the treatments in the pot experiments was in the following order: Prec (17.0%) > TSP (12.8%) ≥ Conc (12.7%) > Sludge (8.8%) ≥ TrAsh (6.9%) ≥ Struv (6.0%) ≥ Comp (5.8%) > Ash (3.4%). The water‐extractable P (WEP) in the incubation experiment largely supported this order and there was a strong correlation between WEP in the incubation experiment and plant P uptake in the pot experiment. Overall, the results of this study demonstrate that it should not automatically be assumed that products recovered with new treatment technologies for P recovery are more effective P fertilizers than the sewage sludge from which they originate. Furthermore, these results indicate that the measurement of water‐extractable P after soil incubation could be a suitable proxy for plant P availability.     

Effects of sewage sludge stabilization on organic‐N mineralization in two soils

Sewage sludge is a valuable source of organic matter, N, P and certain micronutrients that have beneficial effects on plant growth and biomass production. However, sanitary regulations often require the stabilization of sewage materials prior to applying them to soils as biosolids. Environmental regulations also demand appropriate management of biosolid‐N to avoid groundwater contamination. Because stabilization processes usually make sewage sludge less putrescible, we hypothesized that the mineralization rates of organic‐N from stabilized biosolids would be affected. Therefore, this study aimed to evaluate the mineralization of five biosolids in two soils – a sandy Spodosol and a clayey Oxisol. Digested sludge, composted sludge, limed sludge, heat‐dried sludge and solar‐irradiated sludge were mixed with soil samples at a concentration of 32.6 mg N/kg soil (1.0 dry t/ha of digested sludge) and incubated at 25 °C in a humidity chamber for 23 weeks. Results showed that the stabilization processes generally slowed the release of mineral‐N in soils relative to the digested sludge from which the biosolids originated. However, increments in the levels of mineral‐N were more influenced by soil type than by the type of stabilization process applied to the sewage sludge. Mineralization rates were up to 5‐fold higher in the Oxisol than in the Spodosol soil, and as a result, organic‐N in biosolids mineralized 10–24% in Spodosol and 23–52% in Oxisol. Any appropriate plan for the management of biosolid‐N for plant use should consider the interaction between soil type and biosolid type.     

Compost Recycling of Wood Fiber Waste Produced by Paper Manufacture

The composting of wood fiber waste from the manufacture of newsprint is described, with a mixture of wood fiber waste:sewage sludge at a ratio of 1:1 giving best results in a trial of shoot growth of Pinus radiata. An alternative chemical nutrient amendment (initial C:N ratio of 60:1) gave a plant response which was not significantly different to that of sewage sludge. Over a five month period volume reductions of up to 39 percent were observed in the composts, providing potential savings in subsequent transport operations. Use of uncomposted materials or addition of fly- or screen-ash compost amendment (12.5 percent or 25 percent v /v) was inhibitory to plant growth. Concentrations of some heavy metals in Hobart city sewage (particularly of chromium) were high, precluding its long-term use as a soil nutrient supplement. In view of the high heavy metal content of sewage sludge and its high volume to nutrient ratio, it was concluded that composting with chemical amendment was the preferred option for future investigation. Such composts would require ash amendment (or lime equivalent) at concentrations lower than those used in this study to counter acidity produced during composting.     

The use of Folsomia candida (Collembola,Isotomidae) in bioassays of waste

There is a high probability that urban compost, sewage sludge and ash will come in contact with natural terrestrial ecosystems. The present paper investigates the extent to which the Folsomia candida population development test (now a standardised ecotoxicological test, ISO 11267, for testing the impact of pure chemicals on soil fauna) can be applied to the detection of the toxicity of these wastes, the goal being to evaluate ecotoxicity of wastes before they are spread on land. We show that some potentially useful information on waste toxicity can be obtained with this test, but the results must be interpreting with caution, indeed, problems can arise from differences in pH, humidity and organic matter content of the waste relative to the characteristics of the dilution soil. On the basis of the results of these assays, we propose a classification of the toxicity of seven wastes.     

Penicillium bilaii effects on maize growth and P uptake from soil and localized sewage sludge in a rhizobox experiment

With P being a non-renewable resource, the use of microbial inoculants and waste products for more efficient and sustainable P use in plant production has been proposed. We investigated the ability of Penicillium bilaii to mobilize P in a low-fertility soil with or without amendment of sewage sludge as additional P source. Maize was grown for 27 days in rhizoboxes enabling studies of root growth in addition to plant and soil parameters. P. bilaii was inoculated either at the seed or the sewage sludge patch. At early growth stages, P. bilaii inoculation of seeds increased maize shoot length. However, at the end of experiment, the effect had ceased. Root growth was increased by seed P. bilaii inoculation alone and in combination with sewage sludge, whereas patch inoculation was less effective. Colonization studies performed at harvest showed that P. bilaii could not be detected in the maize rhizosphere but stayed at the place of inoculation. In sewage sludge patches, the growth of Penicillium strains other than P. bilaii was stimulated; hence, using sewage sludge for combined P resource and carrier of microbial inoculants is discussed. Unexpectedly, the greater root development of seed-inoculated plants did not result in increased plant P uptake and neither did inoculation at the sewage sludge patch. This study raises the question if the soil P status can be too low for a beneficial effect of additional early root growth and thus a beneficial effect of seed inoculation of P. bilaii.