添加牛粪对蚯蚓处理污泥的影响

采用4个相同的塑料装置,将等量的污泥、EM菌、蚯蚓及不同量的牛粪装入其中并混匀后,通过60 d的培养实验,借助对污泥含水率、pH、TP、TOC和TN的监测及蚯蚓生存状况的考察,探究添加牛粪对蚯蚓处理污泥的影响。结果表明:添加牛粪可以抑制污泥含水率的增加,但不同牛粪添加量对污泥含水率的影响无一定规律性;与初始TP相比,1#~4#中污泥TP增长率分别为81%、97%、56%和102%,除3#外,污泥TP增幅随牛粪添加量的增加而增大;因生物作用,1#~4#污泥TOC均呈下降趋势,1#~4#中污泥TOC分别下降了13.6%、22.4%、21.7%和16.1%;1#~4#污泥TN变化与牛粪添加量的变化之间无明显规律。污泥中添加牛粪,对蚯蚓健康有益。     

Effects of short-term pH fluctuations on cadmium, nickel, lead, and zinc availability to ryegrass in a sewage sludge-amended field

In this field experiment, sewage sludge was applied at 0, 5, 10, and 50tha(-1), and the availability of Cd, Ni, Pb, and Zn was assessed both by ryegrass uptake and by DTPA extractions. The aim was to investigate the role of important soil parameters, particularly pH, on heavy metal availability. It was found that metal uptake and extractability increased significantly in the 50tha(-1) treatment. In the 16th week of the experiment there was a significant, although temporary, increase in DTPA-extractable Cd, Ni, and Zn concentrations. Metal concentrations in ryegrass were also significantly elevated in week 20 compared to the subsequent cuttings. These fluctuations in both DTPA and ryegrass uptake occurred only at 50tha(-1) and were probably induced by a sudden pH decrease measured in the same treatment in week 16. This suggests that soils which have received high applications of sewage sludge may be prone to fluctuations in metal availability.     

Adsorption/desorption of copper by a sandy soil amended with various rates of manure, sewage sludge, and incinerated sewage sludge

Organic amendments are sometimes applied to agricultural soils to improve the physical, chemical, and microbiological properties of the soils. The organic fractions in these soil amendments also influence metal reaction, particularly the adsorption and desorption of metals, which, in turn, determine the bioavailability of the metals and hence their phytotoxicities. In this study, a Quincy fine sandy (mixed, mesic, Xeric Torripsamments) soil was treated with 0 to 160 g kg(-1) rates of either manure, sewage sludge (SS), or incinerated sewage sludge (ISS) and equilibrated in a greenhouse at near field capacity moisture content for 100 days. Following the incubation period, the soil was dried and adsorption of copper (Cu) was evaluated in a batch equilibration study at either 0, 100, 200, or 400 mg L(-1) Cu concentrations in a 0.01M CaCl2 solution. The desorption of adsorbed Cu was evaluated by three successive elutions in 0.01M CaCl2. Copper adsorption increased with an increase in manure rates. At the highest rate of manure addition (160 g kg(-1) soil), Cu adsorption was two-fold greater than that by the unamended soil at all rates of Cu additions. With increasing rates of Cu additions, the adsorption of Cu decreased from 99.4 to 77.6% of Cu applied to the 160 g kg(-1) manure amended soil. The desorption of Cu decreased with an increase in rate of manure amendment. Effects of sewage sludge amendments on Cu adsorption were somewhat similar to those as described for manure additions. Likewise, the desorption of Cu was the least at the high rate of SS addition (160 g kg(-1)), although at the lower rates there was not a clear indication of the rate effects. In contrast to the above two amendments, the ISS amendment had the least effect on Cu adsorption. At the highest rate of ISS amendment, the Cu adsorption was roughly 50% of that at the similar rate of either manure or SS amendments, across all Cu rates.     

Interaction effects of salinity,sewage sludge,and earthworms on the fractionations of Zn and Cu,and the metals uptake by the earthworms in a Zn- and Cu-contaminated calcareous soil

Environmental Science and Pollution Research - This study assessed the effects of salinity and sewage sludge on the fractionation of Zn and Cu in a soil around a lead-zinc mine as well as their...     

Influence of cadmium on carbon and nitrogen mineralization in sewage sludge amended soils

The effect of cadmium on C and N mineralization in sewage sludge amended and unamended sandy loam, loam and clay loam soils was studied during 2 months incubation at 30+/-1 degrees C. The sludge amendment caused 15-39% increase in microbial respiration, with the maximum C mineralization in sandy loam and the minimum in loam soil. The addition of 10 microg Cd g(-1) soil had no remarkable effect on C and N mineralization and microbial biomass; whereas significant decreases in the above parameters were observed at 25 and 50 microg Cd g(-1) soil, irrespective of the sludge addition. Less NO3(-)-N accumulated at higher Cd concentration. Cd recovery was high in sandy loam and low in clay loam soil. DTPA extractable Cd exhibited a significant negative correlation with microbial biomass (r=-0.58* to -0.86*; p < 0.05).     

Phytoextraction of cadmium and zinc from arable soils amended with sewage sludge using Thlaspi caerulescens: development of a predictive model

The objectives of this study were to assess the potential for using Thlaspi caerulescens as a phytoextraction plant and develop a user-advice model, which can predict the frequency of phytoextraction operation required under prescribed conditions. Pot and field trials were conducted using soil collected from a dedicated sewage sludge disposal facility. Soil amendments (sulphuric acid, potassium chloride and EDTA) intended to increase Cd solubility were also tested. Predictive models of Cd and Zn uptake were developed which were able to reproduce the observed pH-dependence of Cd uptake with an apparent maximum around pH 6. Chemical treatments did not significantly increase the uptake of Cd. The periodic use of phytoextraction with T. caerulescens to maintain soils below statutory metal concentration limits, when modern sewage sludges are repeatedly applied, seems very attractive given the non-intrusive and cost-effective nature of the process. The major limitations lie with the large-scale husbandry of T. caerulescens.     

Effects of cadmium,zinc, copper and manganese on hepatic parenchymal cell gluconeogenesis

Abstract

The effects of divalent cations on gluconeogenesis in enzy‐matically isolated rat hepatic parenchymal cells were examined. Cadmium, zinc and copper decreased glucose production from lactate (10 mM). However, manganese at 0.05 to 1.0 mM levels stimulated gluconeogenesis by the cells and reduced the effects of the Cd⁺², Zn⁺² and Cu⁺² on gluconeogenesis. The results indicate that under these in vitro conditions the cations altered an aspect of hepatic function—gluconeogenesis from lactate.     

Effect of soil pH on availability to crops of metals in sewage sludge-treated soils. I. Nickel, copper and zinc uptake and toxicity to ryegrass

The effect of soil pH value on concentrations of Ni, Cu and Zn in ryegrass grown on two sludge-treated soils was examined under field conditions and the maximum permissible soil limit values for these elements were determined which prevent phytotoxicity in crops where sewage sludge is applied to agricultural soils with pH <6.0. Concentrations of all the elements in ryegrass decreased as simple linear functions of increasing soil pH and this response was consistent across the range of pH values measured (pH 4.2-7.0). The response of individual elements tended to differ though, with Cu being less sensitive to changing pH conditions compared with Zn and Ni which responded in a similar manner. The yield of ryegrass also increased with increasing soil pH value probably due to the effects on Zn uptake as the crop content of Zn exceeded known upper critical tissue concentrations for this element at both sites. The proportional change in metal content of ryegrass at pH 5.0, 5.5 and 7.0 from tissue concentrations at pH 6.0 was calculated to determine the permissible soil concentration values on the basis of current maximum limits set by the Sludge Regulations in the UK for sludge-treated agricultural land at pH 6.0-7.0. The estimated permissible concentrations of Ni and Zn in soil corresponded with the regulatory values at the low pH ranges, but were substantially above the current soil limits at pH 7.0 indicating larger quantities of these elements could be safely applied under alkaline soil conditions. The estimated soil limits for Cu implied that the current Regulations were highly precautionary for this element.     

Co-cropping for phyto-separation of zinc and potassium from sewage sludge

The use of sewage sludge as a fertilizer and soil amendment has resulted in high concentrations of heavy metals in the soil limiting its use. The present study was carried out to find the possibility of phyto-separating toxic and beneficial elements from the sludge using suitable plants. Of the five plants tested the hyperaccumulator Sedum alfredii H achieved the greatest removal of Zn, while shoots of Alocasia marorrhiza accumulated high content of K. Co-cropping these two plants on the sludge verified the previous observations on A. marorrhiza and the shoots of this plant could accumulate more than 120 g K kg(-1) dry matter in the median growth stage. Zn hyperaccumulated in Sedum's shoots to an extent more than 10 g kg(-1) dry matter; K concentrated five to ten times in the Alocasia's shoots which could be used as a good organic-K-fertilizer. Hence, the two elements were simultaneously phytoseparated and could be recycled. Furthermore, cultivation of plants in the sludge resulted in significant decreases in total Zn but kept the favorable agronomic characteristics of the sludge material, such as pH, organic matter content, and NPK concentrations and ameliorated its biological stability. These results suggest that simultaneous phyto-separation of toxic and beneficial elements from sewage sludge are possible by co-cropping using specific plants without the input of any chemicals.     

Evaluation of surrogate measures of cadmium, lead, and zinc bioavailability to Eisenia fetida

We evaluated weak-electrolyte (0.1 M Ca(NO3)2) soil extractions and ion-exchange membranes coated with a metal chelator as measures of Cd, Pb, and Zn bioavailability in spiked artificial soil by comparing their metal availability estimates to acute lethal toxicity in the earthworm Eisenia fetida. Ca(NO3)2 extractions were precisely related to toxicity in all toxicity tests, and enabled the development of time-independent LC50S (incipient lethal-levels, ILLs) calculated using exposure levels based on extraction data. ILLs with 95% CIs for the Cd, Pb, and Zn toxicity tests were 9.8 (9.4-10.3), 1.16 (1.11-1.22), and 6.33 (6.18-6.49) Ca(NO3)2-extractable mmol metal/kg soil, respectively. Mixture toxicity of Cd, Pb, and Zn, assessed using the toxic unit (TU) approach, was 1.35 TU, suggesting additivity. Chelating ion-exchange membrane uptake was variable, and not well related to toxicity. Weak-electrolyte extractions show promise as precise, inexpensive surrogate measures of Cd, Pb, and Zn bioavailability in soil.     

Effects of earthworms and effective microorganisms on the composting of sewage sludge with cassava dregs in the tropics

The present study revealed the role of earthworm-effective microorganisms (EM) in converting sewage sludge and cassava dregs into a valuable product. Sewage sludge was toxic to earthworm, therefore it was mixed with cassava dregs in 80:20 proportions (dry weight). Treatments included mixed substrate inoculated versus not inoculated with EM and treated with or without earthworms. The pH, total organic carbon, total nitrogen, and C:N ratio decreased from the initial measurements in the range of 17.43–18.46%, 25.48–33.82%, 19.60–25.37%, and 6.68–14.05% respectively; but electrical conductivity and available phosphorus increased in the range of 113.47–158.16% and 42.42–57.58%, respectively. In addition, they interactively increased total phosphorus from 19.84–63.01% and potassium from 16.41–50.78%, and decreased the polycyclic aromatic hydrocarbons content of substrate from 21.17% to 32.14% with an increase in earthworms from 51.71 to 57.69, respectively. Earthworms and EM could be used together as an efficient method for co-composting sewage sludge plus cassava dregs in the tropics. This could be expected to result in stabilization of waste, increase in nutrients, and reduction of pollutant content.

Implications: The first reports of interaction of earthworms and effective microorganisms in the treatment of sewage sludge and cassava dregs in the tropics. Co-composting was an efficient technology for treating sewage sludge and cassava dregs at the same time, in the tropics. The survival rate of the earthworms both> 95%, the highest number of cocoons (640.33) and hatchlings (4694.33) both in EW+EM (Earthworms added and EM inoculated) treatment. Earthworms and EM (Only EM inoculated) interactively increased total phosphorus and potassium content, and decreased the PAH content of substrate with increase in earthworms.     

Lead,cadmium, zinc,copper and iron in the atmosphere of Greater Bombay

Air concentrations of Pb, Cd, Zn, Cu and Fe have been measured at eight locations in Greater Bombay. Airborne Pb concentration in the city area showed a significant correlation with the vehicular traffic density at the time of sampling. The particle size distribution of Pb aerosol has been studied at two selected locations, in the city of Bombay and a nearby hill station Matheran.     

Determination of cadmium, zinc, copper, chromium and arsenic in crude oil cargoes

One of the sources of trace heavy metal elements in air is emission by the oil industry, either directly through stack emissions from refineries or indirectly from emissions of combustion of hydrocarbons. Emission estimates are based mainly on the trace metal content of the crude oil processed. From a literature study carried out at the beginning of the 1990s it became clear that data on the trace metal content of crudes were scarce and showed a very large scatter. For this reason a measurement programme to assess the occurrence and concentrations of a number of trace metals, i.e. Cadmium (Cd), Zinc (Zn), Copper (Cu), Chromium (Cr), and arsenic (As), in crudes which are regularly processed in the Netherlands, was set up. By drafting strict sampling protocols and by constructing a special sampling device, as many as possible of the additional contamination sources were avoided. The study suggests that sample contamination may explain a significant amount of the scatter and some of the high concentrations reported in the literature for certain metals. The measured variation in the concentrations of Cd, Zn, and Cu is thought to be due to associated water and/or sediment particles from the producing wells or that picked up during transport. The greater consistency in our measurements for Cr and As suggests that these metals are predominantly associated with the hydrocarbon matrix. Based on the results of this work, it can be concluded that emissions of Cd, Zn, Cu, Cr, and As by the oil industry in the Netherlands are most probably significantly lower than hitherto assumed.     

Soil mobility of sewage sludge-derived dissolved organic matter, copper, nickel and zinc

A soil (sandy loam) column leaching study aimed to determine the extent of mobility and co-mobility of Cu, Ni, Zn and dissolved organic matter (DOM) released from a surface-application (equivalent to 50 t ds ha(-1) of anaerobically-digested sewage sludge. Leaching of DOM through the soil column was found to be almost un-retarded. Decidedly similar behaviour was exhibited by Ni suggesting that it migrated as organic complexes. Whilst Cu was also found to be leached, significant retardation was evident. However, the importance of DOM in promoting the mobility of both Cu and Ni was evidenced by their lack of mobility when added to the soil column as inorganic forms. The presence of DOM did not prevent Zn from becoming completely adsorbed by the soil solid phase. In relation to WHO drinking water guidelines, only Ni concentrations showed potential environmental significance, due to the relatively poor retention of Ni by the sludge solid phase.     

Reactions of compost-derived humic substances with lead, copper, cadmium, and zinc

Thermodynamic stability constants of the formation of complexes from the reactions of humic substances with various metals are usually used as parameters to judge the reactivities of both humic substances and metals. However, in calculating the thermodynamic stability constants, complicated processes for the acquisition of activities of components in reactions are absolutely inevitable. In this study, we investigated the average conditional concentration quotients of the complexes formed from the reaction of metals with humic substances and the relations of these quotients to thermodynamic stability constants. The characterized humic substances including HA (MW>1,000), FA (MW>1,000), and FA (MW<1,000) extracted from a swine compost were prepared to react with Pb, Cu, Cd, and Zn at 25 degrees C and at pH 4.00 and 6.50. Reactions of HA (MW>1,000), FA (MW>1,000), and FA (MW<1,000) with the four metals were carried out at 1:0.1, 1:0.5, 1:1, 1:5, and 1:10 ligand:metal stoichiometry. The concentrations of the free ions of Pb, Cu, Cd, and Zn in the reaction systems of metal-HA suspensions and metal-FA solutions were measured by anodic stripping voltammetry (ASV). The sequence of the average conditional concentration quotients of the formed complexes from the reaction of humic substances with metals was FA(MW<1,000)>FA(MW>1,000)>HA(MW>1,000), showing the relative reactivities of the fractions of swine compost-derived humic substances. The sequence of reacting metals with humic substances was Pb>Cu>Cd>Zn, which is in good agreement with the sequence reported by judging the thermodynamic stability constants. The average conditional concentration quotients of the formed complexes from the reaction of humic substances with metals were thus useful parameters that can be directly related to thermodynamic stability constants and other parameters.     

Changes in sewage sludge carbon forms along a treatment stream

The behaviour and fate of macronutrients and pollutants in sewage sludge applied to the land are affected by the chemical composition of the sludge organic matter, which in turn is influenced by both sewage source and by sewage treatment processes. In this study, (13)C nuclear magnetic resonance (NMR) spectroscopy was used to characterise the organic matter of sludges collected at three different points along the treatment stream of a municipal sewage works with a domestic catchment. Sludge at the first point, an undigested liquid (UL) sludge, had a substantially different composition to the anaerobically digested (AD) and dewatered sludge cake (DC) materials, which were similar to each other. In particular, the UL sludge contained more alkyl C than the AD or DC sludges. All three sludges were found to contain mobile alkyl C that is poorly observed using the cross polarisation (CP) technique, necessitating the use of the less sensitive, but more quantitatively reliable direct polarisation (DP) technique to obtain accurate distributions of C types.     

Computational spectroscopic study of copper, cadmium, lead and zinc interactions in the environment

Molecular modelling has been used to investigate the interactions of various heavy metals, in order to understand and possibly to control the nature and behaviour of metals, especially in the aquatic environment. The interactions of copper, cadmium, lead and zinc with organic acids were studied using density functional theory (DFT) calculations. Carboxylic acid was used as a model molecule. The structure of each metal carboxylate was optimized and the vibrational spectrum calculated. The results indicate that there is a shift in the calculated v_S(C=O) of metal carboxylates compared with that of carboxylic acid. It was also found that hexaaqua structures of both cadmium and zinc are stable whereas those of copper and lead are not. Furthermore, dipole moment calculations indicate that cadmium carboxylate dihydrate is more representative of cadmium interactions in the aquatic environment. Moreover, hexaaquo cadmium could further interact with surrounding molecules in the aquatic environment.     

Earthworms as biological monitors of cadmium, copper, lead and zinc in metalliferous soils

Earthworms (Lumbricus rebellus and Dendrodrilus rubidus) were sampled from one uncontaminated and fifteen metal-contaminated sites. Significant positive correlations were found between the earthworm and 'total' (conc. nitric acid-extractable) soil Cd, Cu, Pb and Zn concentrations (data log1) transformed). The relationships were linear, and the accumulation patterns for both species were similar when a single metal was considered, even though there were species difference in mean metal concentrations. Generally, the earthworm Cd concentration exceeded that of the soil; by contrast, the worm Pb concentration was lower than the soil Pb concentration in all but one (acidic, low soil Ca) site. Our observations suggest that Cu and Zn accumulation may be physiologically regulated by both species. Total-soil Cd explained 82-86% of the variability (V2) in earthworm Cd concentration; 52-58% of worm Pb and worm Zn concentrations were explained by the total-soil concentrations of the respective metals. Total-soil Cu explained only 11-32% of the worm Cu concentration. The effect of soil pH, total Ca concentration, cation-exchange capacity (CEC) and organic carbon on metal accumulation by L. rubellus and D. rubidus was investigated by multiple regression analysis. Soil pH (coupled with CEC) and soil Ca had a major influence on Pb accumulation (V2 of worm Pb increased to 77-83%), and there was some evidence that Cd accumulation may be suppressed in extremely organic soils. The edaphic factors investigated had no effect on Cu or Zn accumulation by earthworms. In the context of biomonitoring, it is proposed that earthworms have a potential in a dual role: (1) as 'quantitative' monitors of total-soil metal concentrations (as shown for Cd); and (2) as estimators of 'ecologically significant' soil metal, integrating the effects of edaphic factors (as shown for Pb).     

污泥基生物炭吸附重金属Cd的动力学和热力学

炭化是污泥资资源化利用的重要途径。研究了污泥基生物炭对Cd的吸附过程,探讨了污泥基生物炭吸附重金属Cd的动力学和热力学特征。结果显示污泥基生物炭对Cd的吸附符合准二级动力学方程。Freundlich方程能较好的模拟吸附等温线。随着温度增加,吸附呈现逐渐增强趋势。吸附热力学结果显示35℃时吸附并非自发进行,随着温度增加,吸附转为吸热并自发进行。污泥基生物炭对Cd的吸附主要以化学吸附为主,同时存在多种机制共同作用。研究结果表明污泥基生物炭有作为重金属Cd污染废水修复剂的潜力。