Understanding the Removal and Fate of Selected Drugs of Abuse in Sludge and Biosolids from Australian Wastewater Treatment Operations

Illicit and pharmaceutical drugs are considered to be emerging contaminants of concern,and much research effort has gone into assessing their occurrence in wastewater.However,little information exists on their presence in treated sludge or biosolids.In this study,we examined sludge and biosolids from a large metropolitan wastewater treatment plant(WWTP)in Australia to determine the occurrence of five drugs of abuse,including benzoylecgonine as indicator of cocaine consumption,methamphetamine and 3,4-methylenedioxy methamphetamine(MDMA)as representative illicit stimulants,and codeine and morphine as pharmaceuticals with potential environmental risk.The samples were solid-phase extracted and analyzed by liquid chromatography–tandem mass spectrometry(LC–MS/MS).Benzoylecgonine and MDMA were present in raw sludge but were notably degraded during solids treatment processes,and were not detected in the dewatered sludge(after treatment)or in biosolids.Methamphetamine,codeine,and morphine were detected in all biosolids samples at mean concentrations of 20–50 lg kg^-1.The presence of these three drugs in biosolids shows that these compounds are relatively stable in the solids and in soil,and can persist in biosolids for at least several years.A simple environmental risk assessment based on estimated risk quotients(RQs)for these compounds indicated that the potential environmental risks associated with the land application of biosolids are very low at typical Australian biosolids application rates.

On-Farm Assessment of Biosolids Effects on Nitrogen and Phosphorus Accumulation in Soils

A field plot experiment in a calcareous soil with wheat and maize rotation was carried out for 2 yr. The study aimed to investigate the effects of biosolids （sewage sludge or chicken manure） application on nitrogen （N） and phosphorus （P） accumulation in soils and to develop a model for the effects of biosolids application on available P （Olsen-P） accumulation in soils, by which the quantities of biosolids that can be safely applied to agricultural soils were estimated. The results showed that heavy application of biosolids to agricultural soils based on the N requirement of a wheat-maize rotation cropping system will oversupply P. Soil total N was increased by 0.010 g kg-1 at application rate of 1 ton sewage sludge per hectare. The high ratio of N to P in grains of wheat and maize （from 4.0 to 7.6） and low ratio of N to P in biosolids （〈2） led to more surplus P accumulated in soils. Although plant yields and P uptake by plants increased with increasing quantities of applied biosolids in soils, there was still an average 2.87 mg kg-1 increase in Olsen-P in the plough layer treated with biosolids for every 100 kg P ha-1 surplus. A predictive model was developed based upon the initial Olsen-P in soils, P input rates, crop yield, soil pH, and cultivation time. From the model, it is suggested that sewage sludge could be applied to calcareous soils for 12 yr using the recommended application rate （9 tons ha-1 yr-1）. The field results will be helpful in achieving best management of biosolids application for agricultural production and environmental protection.

Alleviation of Soil Acidity and Aluminium Phytotoxicityin Acid Soils by Using Alkaline-Stabilized Biosolids

A pot experiment was catried out to study alleviation of soil acidity and Al toxicity by applying analkaline-stabilised sewage sludge product (biosolids) to an acid clay sandy loam (pH 5.7) and a strongly acidsandy loam (pH 4.5). Barley (Hondeum vulgare L. cv. Forrester) was used as a test crop and was grownin the sewage sludge-amended (33.5 t sludge DM ha-1) and unamended soils. The results showed that thealka1ine biosloids increased soil pH from 5.7 to 6.9 for the clay sandy loam and from 4.5 to 6.0 for the sandyloam. The sludge product decreased KCl-extractable Al from 0.1 to 0.0 cmol kg-1 for the former soil andfrom 4.0 to 0.1 cmol kg-1 for the latter soil. As a result, barley plants grew much better and grain yieldincreased greatly in the amended treatments compared with the unamended controls. These observationsindicate that alkaline-stabilised biosolids can be used as a liming material for remedying Al phytotoxicity instrongly acid soils by increasing soil pH and lowering Al bioavailability.

Nitrogen Leaching from Saybrook Soil Amended with Biosolid and Polyacrylamide

In this study, Nitrogen leaching following surface application of biosolid with and without polyacrylamide (PAM) coating was investigated using soil column experiments. Three treatments including bare soil (C), a commercially available biosolid (BS) and PAM coated biosolid (PAM + BS), were applied to manually packed (bulk density: 1.3 g·cm-3) growth chamber soil columns (GC columns: 5 cm diameter by 40 cm long) and greenhouse soil columns (GH columns: 15 cm diameter by 40 cm long). The application rates for BS and PAM + BS were 729 and 740 kg/ha, respectively. The GC columns were incubated for 60 days in a dark chamber at 25℃ and no crop was grown in the columns. The GH columns were incubated for 60 days in a greenhouse and Ryegrass (seed rate: 252 kg/ha) was grown in these columns under 16 h daylight and at about 25℃. The columns were irrigated weekly using 270 mL DI-water for GC columns and 850 mL for GH columns and leachate was analyzed for Ammonium (NH4-N), Nitrate (NO3-N) and total Nitrogen (TN). The GH column experiments were repeated with three times greater biosolid application rate (2187 kg/ha) while keeping the PAM and Ryegrass seed rate constant. The leachate volume and NH4-N, NO3-N and TN concentration/load were not significantly different among the treatments for the GH columns but were significantly different during the incubation period. The same was true for GC columns with the exception of NO3-N and TN concentration/load which, overall, were higher for the BS and PAM + BS treatments than for the C treatment. In the beginning of the incubation, the leachate from all treatments (GC and GH) contained the highest NH4-N concentrations (>USEPA target level: 0.1 mg/L) and decreased, in some cases rapidly, to near zero. The NO3-N concentrations were highest in the middle of the incubation and greater than the USEPA target level (10 mg/L). The NO3-N concentrations were lower for cropped GH columns compared to GC columns due to NO3-N uptake by plants. The three fold increase in biosolid application rate did not increase NH4-N concentrations in leachate but did increase NO3-N and TN concentrations/loads in leachate on average 2.5 to 2.7 times. The non-significant differences among treatment means for NH4-N, NO3-N and TN concentrations/loads for the GH columns suggest that land application of biosolid (with or without PAM) to cropped silt loam landscapes at the rates considered may be safe within the context of groundwater pollution.

Impact of nitrogen input from biosolids application on carbon sequestration in a Pinus radiata forest

Background:Forest management practices(e.g.choice of stand density,fertilisation)are just as important in carbon(C)forestry as in other types of forestry and will affect the level of C sequestration and profitability.Because C stored in wood is approximately proportional to the product of its volume and density,it is necessary to account for both volume growth and wood density when assessing the effects of fertilisation on C sequestration in pine forests.Methods:The effects of nitrogen(N)input from biosolids application on forest C sequestration were quantified from an intensively monitored biosolids field trial in a Pinus radiata plantation on a sandy soil in New Zealand.The field trial tested the application of three biosolids rates:Control(no application),Standard(300 kg N⋅ha^(-1) applied every three years),and High(600 kg N⋅ha^(-1) applied every three years),across three levels of stand density:300,450,and 600 stems⋅ha^(-1).Carbon sequestration was estimated using the C-Change model from annual plot measurements of stand density,stem height and diameter,and annual breast height wood densities obtained from increment cores.Results:By age 24 years,N-fertilised trees had sequestered 40 t C⋅ha^(-1) more than unfertilised trees,an increase of 18%.Fertilisation increased stem volume by 23%but reduced stem wood density by 2.5%.Most of the increased C sequestration occurred between age 6 and age 17 years and the Standard rate gave the same increase in C sequestration as the High rate.On average,there was no significant difference in growth rate between fertilised and unfertilised trees after the 17th growth year,but the increased growth ceased earlier at higher stand densities,and later at lower stand densities.Conclusions:This study indicates that 2–3 applications of the Standard rate would have been sufficient to achieve the increased C sequestration,with an applied N to C conversion ratio of 43–65 kg C⋅kg^(-1) N.Our results highlight that N fertilisation will become more widespread under greenhouse gas emissions trading schemes which en-courages forest management practices that improve C sequestration in young forests in New Zealand in particular and other countries in general.

Effect of a Newly Developed Pelleted Papermill Biosolids on Crop and Soil

The US is one of the leading global producers of paper industry with approximately 24 percent of the share of world paper supply. Despite diversity of the feedstock and production methods, C rich papermill biosolids (PB) is a major byproduct of paper production process. Landfilling is the predominant method of PB management. Increasing landfill cost and its potential environmental consequences have incentivized research and development efforts to find beneficial uses for PB. This sensible option reduces the overall paper production costs and increases environmental sustainability. Pelletization of PB increases its marketability by reducing transportation costs. This greenhouse study was conducted to gain a better understanding of the properties and effects of a recently developed pelletized papermill biosolids (PPB) on bell pepper (Capsicum annuum L.) and soil. Urea and PPB were each applied at four total N rates equivalent to 45, 90, 135, and 180 kg N ha﹣1 and an additional control treatments of 0 N was included. The total C and N concentration in this PPB were 379 and 14 g·kg﹣1 respectively and its C:N ratio was 27.2. Nitrogen treatment significantly (P ≤ 0.0839) influenced pepper height, dry biomass, N concentration, and N uptake. Plant height ranged from 31.2 to 44.4 cm;135 kg·ha﹣1 urea-N and PPB-N produced the tallest and shortest plants respectively. Dry biomass of the pepper that did not receive any N, those treated with urea-N or PPB-N were 5.3, 5.7 - 7.5, and 5.9 - 6.5 g·plant﹣1 respectively. Nitrogen concentration in control treatment (0 N) was 36.4 g·kg﹣1 and that of pepper treated with any N ranged from 32.0 - 40.7 g·kg﹣1. There was an inverse numerical, albeit not always statistically significant, relationship between PPB rate and plant N concentration. Generally, pepper treated with urea removed significantly more N from soil than control or PPB treated pepper. Nitrogen uptake by plants that did not receive any N and those amended with urea or PPB were 194, 229 - 270, and 155 - 164 mg·plant﹣1 respectively. Pepper N uptake and concentration data indicate that higher rates of PPB resulted in immobilization of native soil and PPB-N due to its wide C:N ratio (27.2). Nitrogen treatment significantly influenced soil pH, SOM, total C and N (P > 0.1). Soil organic matter and total C in post-harvest soil samples were 17.4 - 19.4 and 21.9 - 35.0 g·kg﹣1 respectively. The observed increase in soil total C and SOM highlights the potential beneficial use of PPB as a means to improve soil health and sequester C in soil. Narrowing the C:N ratio of PPB, by coapplication or incorporation of the mineral N into the pellets will make it an attractive organic N fertilizer.

Corn and Soil Response to a Recently Developed Pelletized Papermill Biosolids

Beneficial utilization of industrial byproducts such as papermill biosolids (PB) provides a unique opportunity to reduce the overall production cost and increase environmental sustainability. Pelletization of a byproduct enhances its marketability by improving the transportation and application. This greenhouse study was conducted to gain a better understanding of the properties and effects of, a recently developed pelletized papermill biosolids (PPB), on corn (Zea mays L.) and soil. Urea and PPB were each applied at four total N rates equivalent to 45, 90, 135, and 180 kg⋅ha−1 and an additional control treatments of 0 was also included. The PPB contained 379 and 14 g⋅kg−1 total N and C and its C:N ratio was 27. Nitrogen treatment significantly (P ⋅plant−1 where application of 180 kg⋅ha−1 of PPB-N produced the smallest plant biomass. Numerically the dry biomass of corn that did not receive any N, corn fertilized with any PPB, and corn fertilized with any urea was 38.3, 26.9 - 41.1 and 38.1 - 40.92 g⋅plant−1 respectively. Nitrogen concentration in corn plants ranged 6.2 - 11.5 g⋅kg−1. Nitrogen concentration in corn that did not receive any urea or corn that received urea was 8.7 - 11.5 g⋅kg−1 and was significantly more than corn treated with any PPB. Total N uptake (removed from soil) by the corn plant was 166 - 455 mg⋅plant−1. Total N uptake by corn that did not receive any N, corn fertilized with any PPB, and corn fertilized with any urea were 327, 166 - 278, and 379 - 455 mg⋅plant−1 respectively. The data suggest that the high C/N ratio (27.2) of PPB resulted in immobilization of PPB-N. Thus the next step will be to research the optimal rates of inorganic N that should be incorporated into this PPB to reduce its C:N to make it an effective high organic matter content N fertilizer. Nitrogen treatment significantly (P g⋅kg−1. The SOM of the treatments fertilized with 90 and 180 kg⋅ha−1 of PPB-N was 19.4 - 19.7 g⋅kg−1 and was significantly higher than soil that did not receive any N. The application of PPB significantly increased the soil total C which was 36.0 and 23.6 g⋅kg−1 in the soil amended with 180 kg⋅ha−1 of PPB-N and the control respectively. The observed increase in SOM and total C in PPB treated soil points to the potential soil health and C sequestration benefits of PPB provided that its C/N ratio can be increased by incorporating inorganic N into it.

Utilizing Water Treatment Residuals to Reduce Phosphorus Runoff from Biosolids

Approximately 40% of biosolids （sewage sludge） produced in the U.S. are incinerated or landfilled rather than land applied due to concern over non-point source P （phosphorus） runoff. The objective of this study was to determine the impact of chemical amendments on WEP （water-extractable phosphorus） in applied treatments and DRP （dissolved reactive phosphorus） in runoff from biosolids-amended soils. Rainfall simulations were conducted in 2006 on field plots fertilized with biosolids that had been treated with alum [（A12804）3＂ 14H20], ferric chloride （FeC13） or an alum-based WTR （water treatment residual） at a rate of 20% （wt/wt） to reduce DRP in runoff. In 2007, rainfall simulations were conducted using WTR/biosolid blends of 15% and 30% （wt/wt） that were allowed to incubate for three weeks prior to application. Cumulative DRP runoff load observed for the 20% WTR treatment was not significantly different from other chemical treatments and resulted in a 45% reduction in DRP runoff as compared to the untreated biosolids application. Cumulative DRP runoff load in 2007 for the 15% and 30% WTR treatments resulted in significantly lower DRP loads compared to untreated biosolids and led to DRP runoff load reductions of 78% and 85% （compared to the untreated biosolids application）, respectively.

Dispersion Modeling of Particulate Matter in Different Size Ranges Releasing from a Biosolids Applied Agricultural Field Using Computational Fluid Dynamics

This paper proposes a methodology using computational fluid dynamics (CFD)-FLUENT to simulate the dispersion of particulate matter releasing from a biosolid applied agricultural field and predict the particulate concentrations for different ranges of particle sizes. The discrete phase model (Lagrangian-Eulerian approach) was used in combination with each of the four turbulence models: Standard kε (kε), Realizable kε (Rkε), Standard kω (kω), and Shear-stress transport k-ω (SST) to predict particulate matter size concentrations for distances downwind of the agricultural field. In this modeling approach, particulates were simulated as discrete phase and air as continuous phase. The predicted particulate matter concentrations were compared statistically with their corresponding field study observations to evaluate the performance of turbulence models. The statistical analysis concluded that among four turbulence models, the discrete phase model when used with Rkε performed the best in predicting particulate matter concentrations for low (u < 2 m/s) and medium (2 < u < 5 m/s) wind speeds. For high (u > 5 m/s) wind speeds, Rkε, kω, and SST showed similar performances. The discrete phase model using Rkε performed very well and modeled the best concentrations for the particle sizes (μm): 0.23, 0.3, 0.4, 0.5, 0.65, 0.8, 1, 1.6, 2, 3, 4, and 5. For particle sizes: 7.5 and 10, the performances of Rkε, kε, kω, and SST were similar.

Postharvest Quality and Safety of Potted Greenhouse Tomato Grown on Forest Soil-Biosolids substrate,Blended with NPK Fertilizer

Studies on the effects of biosolids(BS)amended substrate on food quality and safety in tomato production have not been adequately addressed.The objective of this study was to investigate the influence of composted BS and NPK fertilizer on post-harvest quality and safety of potted greenhouse tomato Solanum lycopersicum L.Potted tomatoes"Maxim F1"were grown in a randomized complete block design with four replications.Inorganic fertilizer NPK(17:17:17) fertilizer was applied at 0,100 kg ha^(-1)(5g per pot)and 200 kg ha^(-1);(10g per pot),BS was applied at 0%,10%,20%,30%,and 40%v/v,in all possible combinations.Tomato were harvested and analyzed for ascorbic acid,chlorophylls,carotenoids and total phenolic compounds;weight loss,fruit firmness,titratable acidity and total soluble solids,as well as heavy metals and microbial contaminants.Results revealed that tomato fruit at 10%BS in combination with NPK fertilizer at 100 kg ha^(-1) had the highestβ-carotene(6.1 mg 100 g^(-1)),lycopene(26.1 mg 100 g^(-1)),ascorbic acids(128.0 mg 100 g^(-1)),total phenolic acids(13.2 mg 100 g^(-1)),total soluble solids(17%).However,the same rates produced tomato fruit with lower titratable acidity(2.2%)and had heavy metal residues within the permissible level,according to International EPA standards on biosolids utilization for food crops production.Similarly,no trace of pathogenic bacteria;Salmonella,Escherichia coli,Staphylococcus was observed on the harvested tomato.This study reveals at BS 10% with NPK fertilizer at 100 kg ha^(-1) substrate as a better option of plant nutrient source for quality and safe greenhouse tomato production.

Influence of the Nature of the Incoming Sludge on the Performance of a Vertical Flow Reed Beds in Dakar-Senegal

This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percentage of leachate recovered and the dryness of accumulated sludge. Plant development was measured through the density, the height and the stem diameter. Purification performance was evaluated from the reduction rate. Biosolids quality was measured after 3 months of maturation. The results show that the clogging frequencies were 9.5%;0% and 3.7%;the volume of leachate recovered was 42.2%;20.4% and 24.7% and, the dryness was 33.4%;61.1% and 52.4% for FS-ST, FS-STT and SS respectively. Plants densities were about, with densities 197.1, 171.3 and 178.3 plants/m2 in beds fed respectively with FS-ST, FS-STT and SS. Despite the high removal rates, the concentrations of pollutants in the leachates are above the Senegalese standard NS 05-061 for discharge into the environment. The biosolids are all mature with C/N and NH4+/NO3?ratios lower than 12 and 1 respectively. The biosolids are also rich in organic and mineral elements. The concentrations of Ascaris eggs are higher than the WHO recommendations. These biosolids should be stored for additional time or composted.

Enhanced biological phosphorus removal using thermal alkaline hydrolyzed municipal wastewater biosolids

This study reports the feasibility of using municipal wastewater biosolids as an alternative carbon source for biological phosphorus removal.The biosolids were treated by a lowtemperature,thermal alkaline hydrolysis process patented by Lystek International Inc.(Cambridge,ON,Canada)to produce short-chain volatile fatty acids and other readily biodegradable organics.Two sequencing batch reactors(SBRs)were operated with synthetic volatile fatty acids(Syn VFA)and readily biodegradable organics produced from the alkaline hydrolysis of municipal wastewater biosolids(Lystek)as the carbon source,respectively.Municipal wastewaters with different strengths and COD:N:P ratios were tested in the study.The reactors’performances were compared with respect to nitrogen and phosphorus removal.It was observed that phosphorus removal efficiencies were between 98%–99%and 90%–97%and nitrogen removal efficiencies were 78%–81%,and 67%for the Syn VFA and Lystek,respectively.However,the kinetics for phosphorus release and uptake during the anaerobic and aerobic stages with Lystek were observed to be significantly lower than Syn VFA due to the presence of higher order VFAs(C4 and above)and other fermentable organics in the Lystek.

Impact of biosolids,ZnO,ZnO/biosolids on bacterial community and enantioselective transformation of racemic–quizalofop–ethyl in agricultural soil

The effects of biosolids,ZnO,and ZnO/biosolids on soil microorganism and the environmental fate of coexisting racemic–quizalofop–ethyl(rac-QE)were investigated.Microbial biomass carbon in native soil,soil/biosolids decreased by 62%and 52%in the presence of ZnO(2‰,weight ratio).The soil bacterial community structure differed significantly among native soil,soil/biosolids,soil/ZnO,and soil/biosolids/ZnO based on a principal co-ordinate analysis(PCo A)of OTUs and one-way ANOVA test of bacterial genera.Chemical transformation caused by ZnO only contributed 4%and 3% of the overall transformation of R-quizalofop-ethyl(R-QE)and S-quizalofop-ethyl(S-QE)in soil/ZnO.The inhibition effect of ZnO on the initial transformation rate of R-QE(rR-QE)and S-QE(rR-QE)in soil only observed when enantiomer concentration was larger than 10 mg/kg.Biosolids embedded with ZnO(biosolids/ZnO)caused a 17%–42% and 22%–38%decrease of rR-QE and rS-QE,although rR-QE and rS-QE increased by 0%–17% and 22%–58%by the addition of biosolids.The results also demonstrated that the effects of biosolids on agricultural soil microorganism and enantioselective transformation of chiral pesticide was altered by the embedded nanoparticles.

Emerging contaminants in biosolids:Presence,fate and analytical techniques

Emerging contaminants(ECs)represent a small fraction of the large chemical pollution puzzle where a wide variety of potentially hazardous chemicals reach the environment,and new compounds are continuously synthesized and released in wastewater treatment plants and ultimately in effluent and biosolids.ECs have been classified into various categories;however,this article focuses on the fate of major categories,namely pharmaceutical and personal care products(PPCPs),per-and poly-fluoroalkyl substances(PFAS),flame retardants,surfactants,endocrine-disrupting chemicals(EDCs),and microplastics(MPs).These ECs when discharged to sewer and downstream wastewater treatment plants can undergo further transformations and either degrade,persist or convert into by-products which have the potential in some cases to be more hazardous.Because of potential dangerous impacts of the availability of these contaminants in the environment,information on the fate and behavior of these pollutants is highly important to develop new strategies,such as the regulation of chemicals imported into Australia and Australian consumer goods and environmental policies to mitigate them in a sustainable way.Moreover,advanced technologies are required for the detection and identification of novel contaminants emerging in the environment at ultra low levels.The application of chromatographic techniques coupled with mass spectroscopy has provided attractive breakthroughs to detect new emerging contaminants.However,it is crucially important to understand the sensitivity and robustness of these analytical techniques when dealing with complex matrices such as biosolids.In addition,most of the literature was focused on selected compounds or a family of compounds and the existing reviews have paid less attention to examine the formation of metabolites during the wastewater treatment process and their impacts on the ecosystem.This review presents an overview of the presence of different classes of ECs around the world,their quantification from different sources like wastewater(influents or effluents),sludge and biosolids.In addition,the transformation of ECs during the treatment process,the formation of intermediate products and their impacts on the environment are also critically discussed.Three major steps of ECs analysis include sample preparation,extraction and clean-up,and analysis;hence,different methods employed for extraction and clean-up,and analytical techniques for identification are thoroughly discussed,their advantages and limitations are also highlighted.This comprehensive review article is believed to enhance the understanding of ECs in sewage sludge and would be useful to the readers of the relevant communities and various stakeholders to investigate potential technologies to maximize destruction of ECs.

Biosolids Management Strategies:an Evaluation of Energy Production as an Alternative to Land Application

Abstract:Currently,more than half of the biosolids produced within the USA are land applied.Land application of biosolids introduces organic contaminants into the environment.There are potential ecological and human health risks associated with land application of biosolids.Biosolids may be used as a renewable energy source.Nutrients may be recovered from biosolids used for energy generation for use as fertilizer.The by-products of biosolids energy generation may be used beneficially in construction materials.It is recommended that energy generation replace land application as the leading biosolids management strategy.

首项污泥国际标准ISO19698:2020浅析

文章介绍了ISO 19698∶2020的编制背景和整体结构框架,对污染物指标、无害化要求与措施、生物固体品质与施用量等方面内容进行了分析解读,并得出其对我国污泥规范标准化工作的启示。

中国城市污泥的重金属含量及其变化趋势

对相关研究结果的系统统计表明 ,Zn是我国城市污泥中平均含量最高的重金属元素 ,其次是Cu ,再次是Cr,而毒性较大的元素Hg、Cd、As含量往往较低 ,通常在几个到十几个mg kg范围内 ;70 %统计样本的As含量在 2 0mg kg以内 ,而Cd、Cr、Cu、Hg、Ni、Pb、Zn含量则分别在 2 8、2 5 0、4 17、5、75、130、170 1mg kg以内 .我国城市污泥中的重金属含量普遍低于英美等发达国家 ,而且其中的重金属含量呈现逐渐降低的趋势 .按照 1984年颁布的《农用污泥污染物控制标准》(GB4 2 84 84 ) ,Zn是我国城市污泥中超标问题最突出的重金属 ,其超标率为 5 5 % ;但按照 2 0 0 2年新修订的《城镇污水处理厂污染物排放标准 (报批稿 )》 ,Zn的超标率仅为 9% .一方面 ,我国的土壤和儿童普遍缺Zn ,另一方面 ,我国现行的农用污泥污染物控制标准对城市污泥中的Zn控制过于严格 ,而且也不尽合理 ,急需对其进一步完善 ,以合理解决城市污泥的处理处置途径 。

粉煤灰与若干有机固体废弃物配施改良土壤的研究进展

鉴于废弃物堆积引起的环境恶化和水土流失、矿山开采等导致土地退化,利用废弃物改良土壤、修复生态环境的研究和技术推广便具有十分重要的意义。文章介绍了粉煤灰与若干有机固体废弃物的理化特性,分析了其单一施用改土的弊病,重点阐述了粉煤灰与有机固体废弃物配施对土壤理化生性质的影响。认为粉煤灰与若干有机固体废弃物配施具有良好的土壤改良效果,也是我国固体废弃物处置和利用的最佳途径之一。此外,分析了有关废弃物配施改土中有待进一步解决的问题,并提出了今后工作的若干建议。

污泥农用对痕量元素在小麦-玉米轮作体系中的积累及转运的影响

利用田间试验初步研究了污泥农用对小麦、玉米大田作物及土壤环境影响以及污泥中痕量元素在土壤与植物可食部分之间转移规律。结果表明,施用污泥后,尤其是36t·hm-2施用量时,土壤中Zn、Cu、Cd、Pb、As和Hg的含量均显著增加,但是施用污泥4.5至36t·hm-2后,除小麦籽粒中Zn、Cu含量和玉米籽粒中Zn、Cr含量显著增加外,其他痕量元素在小麦和玉米籽粒中的含量没有显著增加。作物籽粒中Zn含量与土壤中污泥施加量之间存在着显著的线性回归关系,土壤中增施1t·hm-2污泥,小麦和玉米籽粒中Zn的含量分别增加0.570和0.118mg·kg-1。小麦和玉米籽粒除Ni和Pb的富集系数相近外,对其他痕量元素而言,小麦籽粒的富集系数显著高于玉米籽粒。从痕量元素的累积速率和现行土壤环境质量标准考虑,北京污泥中Hg是优先考虑控制的元素,但是污泥中Hg对食品安全的影响还需要进行长期的大田实验研究。

氮肥形态对污泥农用土壤中重金属活性及玉米对其吸收的影响

采用根箱试验,研究了不同形态氮肥对污泥处理的根-土界面氮素转化、pH、重金属活性以及植物吸收重金属的影响.结果表明,铵态氮肥能降低根际土壤的pH,提高根际土壤中的重金属活性,促进玉米对重金属的吸收;而硝态氮的作用刚好相反.因此,氮肥形态的选择供应可作为控制作物对重金属吸收的一种措施.