Removal of organics from leachates by anaerobic filter

A laboratory-scale study was conducted on two anaerobic filters at several loading rates and four hydraulic detention times. Feed substrates were landfill leachates taken from a recently opened landfill (Keele Valley) and from an older site (Brock North) which had been closed for about 8 years. The strong raw leachate from the new landfill had a COD of 14,000 mg l⁻¹, a BOD/COD ratio of 0.7 and a COD/P value of 17,900. The partially stabilized leachate from the older landfill had a COD of only 3750 mg l⁻¹, a BOD/COD ratio of 0.3 and a COD/P value of 30,640.Results from the treatment of the two leachates were compared with those from a previous study of a “mature” landfill (Beare Road). It was demonstrated that the anaerobic filter could reduce the COD of leachate from landfills of different ages by 90%, at loading rates of 1.26–1.45 kg COD m⁻³ d⁻¹. Total biogas production ranged between 400 and 500 l gas kg⁻¹ COD destroyed and methane content between 75 and 85%. No phosphorus addition was required over the loading range studied.     

Evaluation of on-site biological treatment for landfill leachates and its impact: A size distribution study

A cost effective and widely applied approach for landfill leachate disposal is to discharge it to a municipal wastewater treatment plant (WWTP). The recalcitrant nature of leachate organics and the impact on the downstream WWTPs were comprehensively investigated in this study. Size fractionation by ultrafiltration (UF) and microfiltration (MF) was employed in conjunction with various analyses (TOC, COD, nitrogen species and UV₂₅₄ absorbance) on raw and biologically treated landfill leachates to provide insight into biological treatability. Overall, landfill leachate organics showed bio-refractory properties. Less than half of the organic matter, measured as total organic carbon (TOC), could be removed in the biological processes examined. Size distribution data showed that the <1 thousand Daltons (kDa) fraction is dominant in most untreated and treated landfill leachates, indicating difficulties for membrane treatment. Also, most removal occurred for the <1 kDa fraction in the biological processes, while the intermediate size fractions increased slightly. This may be caused by bio-flocculation and/or partial degradation of larger molecular weight fractions. Organic nitrogen was investigated in this study as one of the first explorations for landfill leachates. Organic nitrogen in landfill leachates was more bio-refractory than other organic matter. UV quenching by landfill leachates was also investigated since it interferes with the UV disinfection at WWTPs. The combination of activated carbon and activated sludge (PACT) showed some effectiveness for reducing UV quenching, indicating that carbon adsorption is a potential method for removal of UV quenching substances. Fourier transform Infrared (FT/IR) data showed that aromatic groups are responsible for the UV quenching phenomenon.     

Fluorescence of leachates from three contrasting landfills

Landfill leachates are composed of a complex mixture of degradation products including dissolved organic matter, which includes a wide range of potentially fluorescent organic molecules and compounds. Here we investigate the excitation-emission matrix fluorescence of landfill leachates from three contrasting landfill sites. Landfill fluorescence properties are all characterized by intense fluorescence at lambda(ex) =220-230nm, and lambda(em) =340-370nm which we suggest derives from fluorescent components of the Xenobiotic Organic Matter fraction such as naphthalene, as well as at lambda(ex) =320-360nm, and lambda(em) =400-470nm from a higher molecular weight fulvic-like fraction. Landfill leachates are characterized by intense fluorescence, with approximately 10(2) intensity units of fluorescence at lambda(ex)=220-230nm, and lambda(em)=340-370nmmg(-1) of total organic carbon, demonstrating leachate detection limits of <0.1mgl(-1) total organic carbon. We demonstrate that for all landfill sites, leachate fluorescence intensity has a strong correlation with ground water quality determinants ammonia, total organic carbon and biochemical oxygen demand. We investigate both within-site and between-site leachate fluorescence properties, and demonstrate that although there is significant within-site variability, leachates from all 3 sites can be statistically discriminated using just fluorescence properties (65% success rate) or with a combination of fluorescence and basic geochemical parameters (85%). Our findings suggest that fluorescence can be used as a rapid and sensitive tracer of leachate contamination of ground water, as well as help discriminate, together with geochemical determinants, leachates from different landfill sources.     

Removal and transformation of recalcitrant organic matter from stabilized saline landfill leachates by coagulation-ozonation coupling processes

The Bordo Poniente sanitary landfill in Mexico City currently receives 11,500 ton/day of solid wastes. The landfill has been in operation since 1985, in what was formerly Texcoco Lake, now a dried-up lakebed. The physico-chemical characteristics of the leachate generated by this particular landfill are altered by the incorporation of freatic saline water present in the area. This paper reports the results from a study evaluating coagulation and ozonation as alternative processes for removing and transforming recalcitrant organic matter from stabilized saline landfill leachate. Coagulation with ferric sulfate was found to remove up to 67% of COD and 96% of leachate color. The remaining 33% COD was removed with ozone. Recalcitrant organic matter removal by ozonation is limited by the reaction kinetic due mainly to ozone's low reactivity with the organic compounds present in the leachates (amines, amides, alcohols, aliphatic compounds, and carboxylic acids). However, ozone contributes greatly to changing the recalcitrant characteristics of organic matter. Leachate biodegradability was found to be significantly enhanced through ozonation: BOD(5) values reach 265%, and the BOD(5)/COD ratio increases from 0.003 to 0.015. Infrared analysis of ozonated leachates shows that the main by-products of recalcitrant organic matter ozonation are an increase in the hydroxyl and carboxylic groups, and the presence of aldehydes groups.     

Characterization of humic substances present in landfill leachates with different landfill ages and its implications

Humic and fulvic acids extracted from landfill leachates were characterized using elemental analysis and various spectroscopic methods. Molecular size distribution of the humic substances (HS) was also determined using batch ultrafiltration technique and permeation coefficient model. The element analysis and spectral features obtained from UV/visible, IR, and 1H and 13C NMR showed that the aromatic character in the leachate HS was relatively lower than that of commercial humic acid (Aldrich Co.), and higher in the HS of older landfill leachate. Fluorescence spectra indicated that humic acids had a relatively higher content of condensed aromatic compounds than the fulvic acids obtained from the same sources, and the spectrum of commercial humic acid showed that aromatic compounds may be present in a much more condensed and complex form. Molecular size distribution data revealed that the leachate humic acids contained a higher percentage of smaller molecules of < 10,000 D, compared with that of the commercial humic acid (45 approximately 49% vs. 33%), and molecular size of the leachate HS had a tendency to increase as landfill age increased. These results indicate that the HS from landfill leachates were in an early stage of humification, and the degree of humification increased as the landfilling age increased, which implies important information on various related researches, such as interactions of HA with pollutants in terrestrial environments, and optimization of leachate treatment processes with respect to landfill age.     

Phthalic acid esters in dissolved fractions of landfill leachates

The distribution of phthalic acid esters (PAEs) (including diisobutylphthalate (DIBP), di-n-butylphthalate (DnBP) and bis(2-ethyl)hexylphthalate (DEHP)) in dissolved organic matter (DOM) fractions of leachates from sanitary or bioreactor landfills was evaluated. The leachate DOM was fractionated into humic acid (HA), fulvic acid (FA) and hydrophilic (HyI) fractions. Measurements showed that the PAEs were bound mostly to the HA fraction in leachate, regardless of their landfill age or the presence of leachate recirculation. The PAEs affinity for HA and FA differed considerably relative to the sorption coefficients reported for model compounds. Molecular weight of DOM correlated with PAEs partition in collected leachate samples fractions while aromaticity was a poor predictor. Based on the presence of phenolic, carboxyl or amide groups in DOM fractions, hydrogen bonding is likely to be involved in interactions between PAEs and leachate DOM. The peptide groups, particularly presented in HA fracion, might explain the strong affinity of PAEs for HA. The fluorescence excitation emission matrix contour plots showed that the HyI fractions shared certain similarities with humic substances in terms of molecular structure, which may be one reason why PAEs exhibited a clear sorption to the HyI fractions.     

Treating landfill leachate using passive aeration trickling filters; effects of leachate characteristics and temperature on rates and process dynamics

Biological ammoniacal-nitrogen (NH₄⁺-N) and organic carbon (TOC) treatment was investigated in replicated mesoscale attached microbial film trickling filters, treating strong and weak strength landfill leachates in batch mode at temperatures of 3, 10, 15 and 30 °C. Comparing leachates, rates of NH₄⁺-N reduction (0.126-0.159 g m^− 2 d^− 1) were predominantly unaffected by leachate characteristics; there were significant differences in TOC rates (0.072-0.194 g m^− 2 d^− 1) but no trend relating to leachate strength. Rates of total oxidised nitrogen (TON) accumulation (0.012-0.144 g m^− 2 d^− 1) were slower for strong leachates. Comparing temperatures, treatment rates varied between 0.029-0.319 g NH₄⁺-N m^− 2 d^− 1 and 0.033-0.251 g C m^− 2 d^− 1 generally increasing with rising temperatures; rates at 3 °C were 9 and 13% of those at 30 °C for NH₄⁺-N and TOC respectively. For the weak leachates (NH₄⁺-N < 140 mg l^− 1) complete oxidation of NH₄⁺-N was achieved. For the strong leachates (NH₄⁺-N 883-1150 mg l^− 1) a biphasic treatment response resulted in NH₄⁺-N removal efficiencies of between 68 and 88% and for one leachate no direct transformation of NH₄⁺-N to TON in bulk leachate. The temporal decoupling of NH₄⁺-N oxidation and TON accumulation in this leachate could not be fully explained by denitrification, volatilisation or anammox, suggesting temporary storage of N within the treatment system. This study demonstrates that passive aeration trickling filters can treat well-buffered high NH₄⁺-N strength landfill leachates under a range of temperatures and that leachate strength has no effect on initial NH₄⁺-N treatment rates. Whether this approach is a practicable option depends on a range of site specific factors.     

Dissolved organic matter (DOM) in recycled leachate of bioreactor landfill

Landfill leachate needs sufficient treatment before safe disposal. Bioreactor landfill technology could effectively degrade the organic matters in recirculated leachate, hence leaving a leachate stream of low biodegradability. This study characterized the dissolved organic matter (DOM) in the leachate from simulated bioreactor landfill columns with or without presence of trace oxygen. The removal efficiencies of this DOM using coagulation-sedimentation or electrolysis processes were demonstrated. Recirculated leachates were sampled from the simulated landfill columns applying conventional mode, intermittent-aeration mode, and natural aeration mode, whose DOM was fractionated into humic acids (HA), fulvic acids (FA) and hydrophilic fractions (HyI) by the XAD-8 resin combined with the cation exchange resin method. The recirculated leachate had low BOD/COD ratio, high humic substances contents, and high aromatic content. Their HA fraction comprised mainly large molecules (>10 k Da), while the FA and HyI were composed of smaller molecules (<50 k and <4 k Da, respectively). With the presence of oxygen, the TOC contents and the contents of HA, FA and HyI in leachate reduced, with FA and HyI fractions of molecular weight (MW) lower than 4 k Da more readily degraded. The organic matters left in leachates from intermittent-aeration mode and natural aeration mode were of low biodegradability. It was tested in the following sections the effects of coagulation-sedimentation process and of electrolysis process on the removal of residual DOM in recirculated leachate. Coagulation-sedimentation tests revealed that poly ferric sulphate (PFS) could remove more COD (58.1%) from leachate than polyaluminum chloride (PACl) (22.9%), particularly on the HA fraction with MW>10 k Da. Coagulation-sedimentation could not remove most of HyI in leachate. Furthermore, the corresponding BOD/COD ratio was not improved through coagulation. Electrolysis test could also effectively removed HA of MW>10 k Da. However, the biodegradability of treated effluent considerably was improved. The electrolysis could decompose high MW substances and increase biodegradability of recirculated leachate from bioreactor landfill.     

PAEs and BPA removal in landfill leachate with Fenton process and its relationship with leachate DOM composition

An increasing attention has been paid to the trace endocrine disrupting compounds (EDCs) in landfill leachate. In this paper, the removal of EDCs including phthalic acid esters (PAEs) and bisphenol A (BPA) from the fresh and mature landfill leachate by Fenton treatment was studied. More than 40% of PAEs and about 62% of BPA were removed from the raw mature leachate while only 20% of PAEs and 37% of BPA in the raw fresh leachate were reduced, respectively. After the fresh and mature leachates were spiked with PAEs to 1.5 mg L^− 1 and BPA to 0.08 mg L^− 1, the removal efficiencies of BPA and PAEs increased to more than 88%. The results indicated that the removing efficiencies of the EDCs in the leachate had a relationship with their concentrations, and that the trace levels of EDCs in leachate challenged the treatment capacity of the Fenton process. Most of the EDCs in the enriched leachate were removed by oxidation, which had no clear correlation with the hydrophobicity of the EDCs. The flocculation played an important role in the removal of di-(2-ethylhexyl) phthalate that could not be completely oxidized in the Fenton process, in that the EDCs with high n-octanol/water partition coefficient inclined to precipitate after the Fenton process. The dissolved organic matter (DOM) in the fresh leachate inhibited the EDCs removal more than the DOM in the mature leachate did. Both the composition of the leachate DOM and the characteristics of the EDCs determined the removing efficiencies of the EDCs in the Fenton process.     

Optimizing the treatment of landfill leachate by conventional Fenton and photo-Fenton processes

Landfill, a matured and economically appealing technology, is the ultimate approach for the management of municipal solid wastes. However, the inevitable generation of leachate from landfill requires further treatment. Among the various leachate treatment technologies available, advanced oxidation processes (AOPs) are among powerful methods to deal with the refractory organic constituents, and the Fenton reagent has evolved as one promising AOPs for the treatment of leachates. Particularly, the combination of UV-radiation with Fenton's reagent has been reported to be a method that allows both the photo-regeneration of Fe²⁺ and photo-decarboxylation of ferric carboxylates. In this study, Fenton and photo-Fenton processes were fine tuned for the treatment of leachates from the Colmenar Viejo (Madrid, Spain) Landfill. Results showed that it is possible to define a set of conditions under which the same COD and TOC removals (≈ 70%) could be achieved with both the conventional and photo-Fenton processes. But Fenton process generated an important quantity of iron sludge, which will require further disposal, when performed under optimal COD removal conditions. Furthermore conventional Fenton process was able to achieve slightly over an 80% COD removal from a “young” leachate, while for “old” and ”mixed” leachates was close to a 70%. The main advantage showed by the photo-assisted Fenton treatment of landfill leachate was that it consumed 32 times less iron and produced 25 times less sludge volume yielding the same COD removal results than a conventional Fenton treatment.     

The treatment of leachates from domestic wastes in landfills—I: Aerobic biological treatment of a medium-strength leachate

A medium-strength leachate from domestic solid wastes in a landfill (COD 5000 mg l⁻¹, BOD 3000 mg l⁻¹ was treated using aerobic biological processes in continuous-flow, laboratory-scale reactors at low temperatures. Each unit was completely mixed, and mixed liquor was wasted such that solids retention time (SRT) was equal to the hydraulic retention period.At 10 C with addition of phosphate (COD:P less than 100:1) SRT values of 10 days were required to obtained well-clarified effluents, and high removal of BOD (>;98%) and COD (>;92%). Reduction of temperature to 5°C resulted in adverse effects on settling of sludges from units with SRT values of less than 10 days, but in other units good removal of organic materials could still be obtained. These units operated successfully with concentrations of mixed liquor volatile suspended solids (MLVSS) of 1450 mg l⁻¹, equivalent to a ratio of F/M of 0.21 kg BOD kg⁻¹ MLVSS day⁻¹ or less. Removal of ammoniacal nitrogen which took place (influent concentration 80 mg l⁻¹ as N) resulted from incorporation in biomass, and at SRT values of 10 days no nitrification took place at 5 or 10 C. Higher concentrations of ammonia in influent leachates resulted in ammonia in effluents when the ratio of BOD:N was less than about 100:3.6. Increasing the SRT of units to 20 days resulted in erratic conversion to nitrite, but reduced pH-values and possible simultaneous denitrification caused floating sludges and poorly-clarified effluents. Removal of ammonia is identified as a major problem when treating leachates, and further research is recommended.     

Migration behavior of landfill leachate contaminants through alternative composite liners

Four identical pilot-scale landfill reactors with different alternative composite liners were simultaneously operated for a period of about 540 days to investigate and to simulate the migration behaviors of phenolic compounds (phenol, 2-CP, 2-MP, 3-MP, 4-MP, 2-NP, 4-NP, 2,4-DNP, 2,4-DCP, 2,6-DCP, 2,4,5-TCP, 2,4,6-TCP, 2,3,4,6-TeCP, PCP) and heavy metals (Pb, Cu, Zn, Cr, Cd, Ni) from landfill leachate to the groundwater. Alternative landfill liners of four reactors consist of R1: Compacted clay liner (10 cm + 10 cm, k = 10⁻⁸ m/sn), R2: Geomembrane (2 mm HDPE) + compacted clay liner (10 cm + 10 cm, k = 10⁻⁸ m/sn), R3: Geomembrane (2 mm HDPE) + compacted clay liner (10 cm, k = 10⁻⁸ m/sn) + bentonite liner (2 cm) + compacted clay liner (10 cm, k = 10⁻⁸ m/sn), and R4: Geomembrane (2 mm HDPE) + compacted clay liner (10 cm, k = 10⁻⁸ m/sn) + zeolite liner (2 cm) + compacted clay liner (10 cm, k = 10⁻⁸ m/sn). Wastes representing Istanbul municipal solid wastes were disposed in the reactors. To represent bioreactor landfills, reactors were operated by leachate recirculation. To monitor and control anaerobic degradation in the reactors, variations of conventional parameters (pH, alkalinity, chloride, conductivity, COD, TOC, TKN, ammonia and alcaly metals) were also investigated in landfill leachate samples. The results of this study showed that about 35-50% of migration of organic contaminants (phenolic compounds) and 55-100% of migration of inorganic contaminants (heavy metals) to the model groundwater could be effectively reduced with the use of bentonite and zeolite materials in landfill liner systems. Although leachate contaminants can reach to the groundwater in trace concentrations, findings of this study concluded that the release of these compounds from landfill leachate to the groundwater may potentially be of an important environmental concern based on the experimental findings.     

Screening of organic matter in leachates from sanitary landfills using gas chromatography combined with mass spectrometry

Sanitary landfills are potential groundwater pollution sources, normally producing leachate with very high content of organic matter. Leachates from five Danish sanitary landfills were sampled in order to investigate the composition of the organic matter. The samples were extracted using dichloromethane followed by sodium hydroxide solution, in this way dividing the sample into one phase containing the basic and neutral compounds and one containing the acidic compounds. One of the leachates was extracted using pentane, for analysis of volatile compounds. The three extracts were analysed using gas chromatography combined with mass spectrometry. Several compounds were identified, including chlorinated pesticides (2 of the 5 leachates), aromatic carboxylic acids and alkylbenzenes. Benzene, toluene and trichloroethylene were found in the leachate analysed for volatile compounds. Some of the compounds identified in this work have been reported in the literature to give rise to severe groundwater problems.     

Organic indicators of groundwater pollution by a sanitary landfill

The organic composition of leachate from the Barcelona sanitary landfill is described. According to the low degree of stabilization of the disposed garbage the acid fraction accounts for 80–90% of the total organic extract. More than 50 individual organic components have been identified, indicating catabolic degradation of lipids (e.g. C₄–C₁₁ carboxylic acids), proteins (e.g. indole derivatives) and lignins (e.g. p-hydroxyphenyl derivatives) or simply compounds originally present in the refuse that have been washed out by percolating waters (nicotine, caffeine, phthalates).To obtain a monitoring system for the groundwater pollution originated by this landfill leachate, an analytical method is proposed based on the GC-ECD fingerprinting of groundwater acidic extracts after derivatization with PFB bromide. The chromatogram contains carboxylic and phenolic components and the profiles exhibited by waters from several test wells in the downstream edge of the landfill were indicative of the suspected leachate pollution.     

DISTRIBUTION OF TRITIUM IN THE LEACHATES AND METHANE GAS CONDENSATES FROM MUNICIPAL WASTE LANDFILLS IN KOREA

In this paper, the tritium levels in the leachates and methane gas condensates which have occurred at 13 sanitary landfills of municipal solid wastes (MSW) are investigated and reported. During the 6 months investigation period, the mean tritium concentrations of the raw leachates were distributed from 17 to 1,196 TU. They corresponded to several scores or hundreds higher tritium levels than that of the normal environmental level except for two cases. High tritium levels were also detected in the effluents of the leachate treatment facilities. Generally, the tritium existed in the dissolving fraction of the leachate but for some cases about 10% of the total tritium content was present as colloidal particles of over 0.45 μm in size. In general, the relationship between the tritium and other contaminants in the raw leachate was low, but it was relatively high between the tritium and TOC. Thus, it is predicted that the dissolving state of the tritium in the leachates would be affected by the tritium sources of the tipped wastes in a MSW.     

The chemistry of cadmium in natural water—II. The adsorption of cadmium on river muds and naturally occurring solids

The adsorption of cadmium on mud solids and particles of clay, silica, humic material and other naturally occurring solids has been studied. Radiochemical methods were employed so that cadmium concentrations in the μg l⁻¹ range could be used. The variation of the extent of adsorption with many of the large number of factors involved was investigated, concentration factors (distribution coefficients) were determined, and in the course of the work, loss of cadmium by adsorption on container surfaces and filters was investigated.Rates of adsorption and desorption were shown to be rapid. Concentration factors for river muds varied between 5000 and 50,000 and depended mainly on the type of solid, its state of subdivision, the concentration of metal ion present, the time of contact and the concentration of complexing ligands. Humic material appeared to be the main component of river mud responsible for adsorption. Adsorption and desorption processes are likely to be major factors in controlling the concentration of cadmium in natural waters and will tend to counteract changes in the concentration of the metal ion in solution.     

Oxone/Co oxidation as an advanced oxidation process: Comparison with traditional Fenton oxidation for treatment of landfill leachate

In this paper, the application of Fenton and Oxone/Co²⁺ oxidation processes for landfill leachate treatment was investigated. The removal of the chemical oxygen demand (COD), suspended substances (SS) and the color of the landfill leachate by Fenton oxidation to that by Oxone/Co²⁺ oxidation were compared under optimal operational conditions. For Fenton oxidation process, the optimal conditions were determined as: [H₂O₂] = 80 mmol L⁻¹, [H₂O₂]/[Fe²⁺] = 2.0, initial pH = 2.5, reaction temperature = 37.5 ± 1 °C, reaction time = 160 min, number of stepwise addition = 3. Under the given conditions, 56.9% of the COD removal efficiency was achieved, but the SS and the color of the treated landfill leachate increased due to the generation of a large quantity of ferric hydroxide sludge. In reference to Oxone/Co²⁺ oxidation process, the optimal conditions were determined as: [Oxone] = 4.5 mmol L⁻¹, [Oxone]/[Co²⁺] = 10⁴, pH = 6.5, reaction temperature = 30 ± 1 °C, reaction time = 300 min, number of stepwise addition = 7, the COD, SS and the color removal efficiencies were 57.5, 53.3 and 83.3%, respectively. From this work, it can be concluded that Oxone/Co²⁺ oxidation process demonstrated higher degradation efficiencies of the COD, SS and color for landfill leachate treatment than that by Fenton oxidation process. It also suggested that Oxone/Co²⁺ oxidation process could be considered as one of the most promising technologies for practical applicability to treat landfill leachate in large scale. For further improving the efficiency of Oxone/Co²⁺ oxidation process, we proposed that combination of it with other technologies in future such as ultraviolet, ultrasound and biological methods.     

城市垃圾卫生填埋场垂直防渗技术

针对城市垃圾卫生填埋场渗滤液成分复杂、浓度高、污染性强的特点，分析了在卫生填埋场构筑防渗系统的功能要求，根据粘土固化浆液的组成特征和固化机理，研究了粘土固化注浆帷幕对渗滤液的抗渗性能和对污染物质的吸附特性，结合粘土固化注浆帷幕在卫生填埋场防渗工程中的应用实例，从施工质量检测、防渗效果监测和技术经济角度，证明了这种垂直防渗技术应用在垃圾填埋场的可靠性和经济性。     

The determination of cadmium. lead, copper and zinc in ground water, estuarine water, sewage and sewage effluent by anodic stripping voltammetry

Anodic stripping voltammetry (ASV) using the thin-film mercury electrode was shown to be a successful technique for the determination of total (free plus complexed) trace metal concentrations in various types of aqueous sample. The method developed involved the minimum of sample treatment and required only simple and inexpensive equipment. The practical limit of sensitivity was about 0·1 μg I⁻¹ for cadmium, lead and copper. The determination of zinc was found to be complicated by the formation of an intermetallic compound with copper. Interference by other trace metals and by complexing agents was investigated. Photochemical oxidation for the decomposition of complexes of the metals with organic ligands in filtered sewage and sewage effluent was found to be successful, although the process is slower for cadmium than for the other metals. Good agreement with atomic absorption spectroscopy was obtained for all the types of aqueous sample investigated. Possible improvements of the ASV technique are discussed.