Degradation and environmental risk of surfactants after the application of compost sludge to the soil

In this work, the degradation of anionic and non-ionic surfactants in agricultural soil amended with sewage sludge is reported. The compounds analysed were: linear alkylbenzene sulphonates (LAS) with a 10-13 carbon alkylic chain, and nonylphenolic compounds (NPE), including nonylphenol (NP) and nonylphenol ethoxylates with one and two ethoxy groups (NP1EO and NP2EO). The degradation studies were carried out under winter (12.7°C) and summer (22.4°C) conditions in Andalusia region. The concentration of LAS was reduced to 2% of the initial concentration 100 day after sludge-application to the soil. The half-life time measured for LAS homologues were ranged between 4 and 14days at 12.7°C and between 4 and 7 days at 22.4°C. With regard to NPE compounds, after 8 and 4days from the beginning of the experiment at 12.7 and 22.4°C, respectively, their concentration levels were increased to 6.5 and 13.5mg/kgdm (dry matter) as consequence of the degradation of nonylphenol polyethoxylates. These concentration levels were reduced to 5% after 63 and 70 days for 12.7°C and 22.4°C, respectively. The half-life times measured for NPEs were from 8 to 16 days at 12.7°C and from 8 to 18 days at 22.4°C. Environmental risk assessment revealed that for LAS homologues no environment risk could be expected after 7 and 8 days of sludge application to the soil for 22.4 and 12.7°C, respectively; however, potential toxic effects could be observed for the nonylphenolic compounds during the first 56 days after sludge application to the soil.     

Biotests for environmental quality assessment of composted sewage sludge

The quality of sewage sludge-based products, such as composts and growth media, is affected by the contamination of sewage sludge with, potentially, hundreds of different substances. Therefore, it is difficult to achieve the reliable environmental quality assessment of sewage sludge-based products solely based on chemical analysis. In the present work, we demonstrate the use of the kinetic luminescent bacteria test (ISO 21338) to evaluate acute toxicity and the Vitotox? test to monitor genotoxicity of sewage sludge and composted sewages sludge. In addition, endocrine-disrupting and dioxin-like activity was studied using yeast-cell-based assays. The relative contribution of industrial waste water treated at the Waste Water Treatment Plants led to elevated concentrations of polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polychlorinated dibenzo-p-dioxins and -furans (PCDD/F) in sewage sludge. The effect of elevated amounts of organic contaminants could also be identified with biotests able to demonstrate higher acute toxicity, genotoxicity, and potential for endocrine-disruptive properties. Additional extraction steps in kinetic luminescent bacteria test with DMSO and hexane increased the level of toxicity detected. Composting in a pilot-scale efficiently reduced the amounts of linear alkylbenzensulphonates (LASs), nonylphenols and nonylphenolethoxylates (NPE/NPs) and PAH with relative removal efficiencies of 84%, 61% and 56%. In addition, decrease in acute toxicity, genotoxicity and endocrorine-disrupting and dioxin-like activity during composting could be detected. However, the biotests did have limitations in accessing the ecotoxicity of test media rich with organic matter, such as sewage sludge and compost, and effects of sample characteristics on biotest organisms must be acknowledged. The compost matrix itself, however, which contained a high amount of nutrients, bark, and peat, reduced the sensitivity of the genotoxicity tests and yeast bioreporter assays.     

The production, use and quality of sewage sludge in Denmark

In Denmark, the production of municipal sewage sludge decreased from approximately 170,000 ton d.m. in 1994 to 140,000 ton d.m. in 2002. The sludge is handled and treated in a number of ways. The quality of Danish sludge has steadily improved since the middle of the 1980s, when the first set of quality criteria for heavy metals was introduced. In 1997, cut-off criteria for the organic pollutants, LAS, DEHP, nonylphenol and PAHs were introduced. Effective control from authorities, voluntary phasing out agreements with industry, improved source identification tools, better handling and after-care methods have in combination with higher waste duties led to a significant reduction in the sludge level of especially cadmium, mercury, chromium, LAS and nonylphenol. The increased quality demand has, nevertheless, also led to a minor reduction in the use of sewage sludge as organic fertiliser on agricultural land.     

Priority and emerging pollutants in sewage sludge and fate during sludge treatment

This paper aims at characterizing the quality of different treated sludges from Paris conurbation in terms of micropollutants and assessing their fate during different sludge treatment processes (STP). To achieve this, a large panel of priority and emerging pollutants (n = 117) have been monitored in different STPs from Parisian wastewater treatment plants including anaerobic digestion, thermal drying, centrifugation and a sludge cake production unit. Considering the quality of treated sludges, comparable micropollutant patterns are found for the different sludges investigated (in mg/kg DM – dry matter). 35 compounds were detected in treated sludges. Some compounds (metals, organotins, alkylphenols, DEHP) are found in every kinds of sludge while pesticides or VOCs are never detected. Sludge cake is the most contaminated sludge, resulting from concentration phenomenon during different treatments. As regards treatments, both centrifugation and thermal drying have broadly no important impact on sludge contamination for metals and organic compounds, even if a slight removal seems to be possible with thermal drying for several compounds by abiotic transfers. Three different behaviors can be highlighted in anaerobic digestion: (i) no removal (metals), (ii) removal following dry matter (DM) elimination (organotins and NP) and iii) removal higher than DM (alkylphenols – except NP – BDE 209 and DEHP). Thus, this process allows a clear removal of biodegradable micropollutants which could be potentially significantly improved by increasing DM removal through operational parameters modifications (retention time, temperature, pre-treatment, etc.).     

Comparative study of the methods used for treatment and final disposal of sewage sludge in European countries

Municipal wastewater treatment results to the production of large quantities of sewage sludge, which requires proper and environmentally accepted management before final disposal. In European Union, sludge management remains an open and challenging issue for the Member States as the relative European legislation is fragmentary and quite old, while the published data concerning sludge treatment and disposal in different European countries are often incomplete and inhomogeneous. The main objective of the current study was to outline the current situation and discuss future perspectives for sludge treatment and disposal in EU countries. According to the results, specific sludge production is differentiated significantly between European countries, ranging from 0.1 kg per population equivalent (p.e.) and year (Malta) to 30.8 kg per p.e. and year (Austria). More stringent legislations comparing to European Directive 86/278/EC have been adopted for sludge disposal in soil by several European countries, setting lower limit values for heavy metals as well as limit values for pathogens and organic micropollutants. A great variety of sludge treatment technologies are used in EU countries, while differences are observed between Member States. Anaerobic and aerobic digestion seems to be the most popular stabilization methods, applying in 24 and 20 countries, respectively. Mechanical sludge dewatering is preferred comparing to the use of drying beds, while thermal drying is mainly applied in EU-15 countries (old Member States) and especially in Germany, Italy, France and UK. Regarding sludge final disposal, sludge reuse (including direct agricultural application and composting) seems to be the predominant choice for sludge management in EU-15 (53% of produced sludge), following by incineration (21% of produced sludge). On the other hand, the most common disposal method in EU-12 countries (new Member States that joined EU after 2004) is still landfilling. Due to the obligations set by Directive 91/271/EC, a temporary increase of sludge amounts that are disposed in landfills is expected during the following years in EU-12 countries. Beside the above, sludge reuse in land and sludge incineration seem to be the main practices further adopted in EU-27 (all Member States) up to 2020. The reinforcement of these disposal practices will probably result to adoption of advanced sludge treatment technologies in order to achieve higher pathogens removal, odors control and removal of toxic compounds and ensure human health and environmental protection.     

Production of well-matured compost from night-soil sludge by an extremely short period of thermophilic composting

The effect of various operational conditions on the decomposition of organic material during the composting of night-soil treatment sludge was quantitatively examined. The optimum composting conditions were found to be a temperature of ca. 60 °C and an initial pH value of 8. Rapid decomposition of organic matter ceased by the sixth day of composting under these optimum conditions, and the final value of the cumulative emission of carbon (E_C), which represents the degree of organic matter decomposition, was less than 40%, indicating that the sludge contained only a small amount of easily degradable organic material. A plant growth assay using Komatsuna (Brassica campestris L. var. rapiferafroug) in a 1/5000a standard cultivation pot was then conducted for the compost at various degrees of organic matter decomposition: the raw composting material, the final compost obtained on day 6, and the 2 intermediate compost products (i.e., E_C = 10% and 20%). It was found that the larger the E_C, the greater the yield of Komatsuna growth. It was also found that 6 days of composting is sufficient to promote Komatsuna growth at the standard loading level, which is equivalent to a 1.5 g N/pot, since the promotion effect was as high as that obtained using chemical fertilizer. It can therefore be concluded that well-matured compost could be obtained in a short period of time (i.e., as early as 6 days), when night-soil sludge is composted under optimum conditions.     

Behavior of PAHs from sewage sludge incinerators in Korea

Although production of sewage sludge increases every year, its proper treatment has only been recently raised as a new issue, as current landfill and ocean dumping arrangements are expected to become increasingly difficult to manage in the future. The Korean Ministry of Environment plans to diversify its processing facilities and expand its processing systems by 2011, with the purpose of processing all sludge produced in Korea. According to this plan, incineration (including incineration of municipal wastes) will process 30% of the entire sewage sludge throughout the country in 2011. This study reviews the characteristics of PAH, which is one of the organic substances found in sewage sludge during the incinerating process. The total amount of PAH produced from sewage sludge incineration was found to be 6.103 mg/kg on average, and investigation performed on 16 PAHs of inlets and outlets of the air control devices at five full-scale incineration facilities showed that concentrations of the PAHs on the inlet and on the outlet ranged from 3.926 to 925.748 microg/m(3) and from 1.153 to 189.449 microg/m(3), respectively. In the case of the incineration facility fed with municipal waste (95%) and sewage sludge (5%), the total of the PAH emissions concentration was higher than that found at the incineration facilities used exclusively to treat sewage. The combustion of waste vinyl and plastics contained in municipal waste fed into the facility might contribute to the high levels of PAHs in the stack gas. However more investigation is needed on the production mechanism of PAHs at different operating conditions of the incineration facilities, such as the types of waste, and other relevant factors.     

Changes in soil chemical and microbiological properties during 4 years of application of various organic residues

A 4-year field trial was established in eastern Sweden to evaluate the effects of organic waste on soil chemical and microbiological variables. A simple crop rotation with barley and oats was treated with either compost from household waste, biogas residue from household waste, anaerobically treated sewage sludge, pig manure, cow manure or mineral fertilizer. All fertilizers were amended in rates corresponding to 100kgNha(-1)year(-1). The effects of the different types of organic waste were evaluated by subjecting soil samples, taken each autumn 4 weeks after harvest, to an extensive set of soil chemical (pH, Org-C, Tot-N, Tot-P, Tot-S, P-AL, P-Olsen, K-AL, and some metals) and microbiological (B-resp, SIR, microSIR active and dormant microorganisms, PDA, microPDA, PAO, Alk-P and N-min) analyses. Results show that compost increased pH, and that compost as well as sewage sludge increased plant available phosphorus; however, the chemical analysis showed few clear trends over the 4 years and few clear relations to plant yield or soil quality. Biogas residues increased substrate induced respiration (SIR) and, compared to the untreated control amendment of biogas residues as well as compost, led to a higher proportion of active microorganisms. In addition, biogas residues increased potential ammonia oxidation rate (PAO), nitrogen mineralization capacity (N-min) as well as the specific growth rate constant of denitrifiers (microPDA). Despite rather large concentrations of heavy metals in some of the waste products, no negative effects could be seen on either chemical or microbiological soil properties. Changes in soil microbial properties appeared to occur more rapidly than most chemical properties. This suggests that soil microbial processes can function as more sensitive indicators of short-term changes in soil properties due to amendment of organic wastes.     

Bacterial community patterns and thermal analyses of composts of various origins.

During composting, the degradation of organic waste is accompanied and driven by a succession of microbial populations exhibiting a broad range of functional capabilities. Detailed inventories of the microbial communities in mature compost, however, are not available. Mature composts, originating from biowaste as well as sewage sludge and anaerobic sludge, were studied by denaturing gradient gel electrophoresis-fingerprints after polymerase chain reaction (PCR) amplification of the 16S rRNA genes using three different universal primer pairs, as well as by differential scanning calorimetry and thermogravimetry. The composts of different origin had different bacterial communities. The influence of different 16S rDNA primer sets on the same batches of compost DNA was evaluated. The clearest separation of different compost types was obtained by using the PCR primer pair 338f + 518r which is suggested for future applications. Communities from the different biowaste compost samples clustered together and could be separated from sewage sludge communities indicating the establishment of different microbial consortia. A similar differentiation of composts was found with the thermogavimetric analyses. It may thus be concluded that the resulting humus quality is closely linked to the microbial communities involved.     

Sources and behaviour of polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in Spanish sewage sludge

Presence, sources and behaviour of polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were evaluated in Spanish sewage sludge. A total of 120 samples were seasonally collected from October 2005 to September 2006 at 31 urban wastewater treatment plants (WWTPs). Concentrations of PBDEs (ranging between 57.5 and 2606 ng/g dry weight) were two to three orders of magnitude higher than those obtained for PCDDs (0.17-5.03 ng/g d.w.) and PCDFs (0.05-3.07 ng/g d.w.). All the samples presented International Toxicity Equivalents (I-TEQ) levels (ranging between 2.06 and 44.4 ng/kg d.w.) below the limit values proposed by European Union for land application. Congener patterns evaluation revealed that the use of Deca-BDE commercial mixture seems to be the major source of PBDEs in the sludge. Nevertheless, origin of PCDD/Fs should be related to atmospheric deposition, faeces and presence of PCDD/Fs precursors such as pentachlorophenol in the sludge. No correlations (p > 0.05) were found between pollutant concentrations (PBDEs and PCDD/Fs) and wastewater treatment plant (WWTP) characteristics (capacity nor sludge rate). Lower levels of PBDEs and PCDFs were found in WWTPs using biological nitrogen and phosphorous elimination, suggesting that these compounds are susceptible of microbial elimination. According to our knowledge, this is the first work comparing together both PBDEs and PCDD/Fs sludge patterns.     

Sequential extraction of metals from mixed and digested sludge from aerobic WWTPs sited in the south of Spain

The content of heavy metals is the major limitation to the application of sewage sludge in soil. However, assessment of the pollution by total metal determination does not reveal the true environmental impact. It is necessary to apply sequential extraction techniques to obtain suitable information about their bioavailability or toxicity. In this paper, sequential extraction of metals from sludge before and after aerobic digestion was applied to sludge from five WWTPs in southern Spain to obtain information about the influence of the digestion treatment in the concentration of the metals. The percentage of each metal as residual, oxidizable, reducible and exchangeable form was calculated. For this purpose, sludge samples were collected from two different points of the plants, namely, sludge from the mixture (primary and secondary sludge) tank (mixed sludge, MS) and the digested-dewatered sludge (final sludge, FS). Heavy metals, Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti and Zn, were extracted following the sequential extraction scheme proposed by the Standards, Measurements and Testing Programme of the European Commission and determined by inductively-coupled plasma atomic emission spectrometry. The total concentration of heavy metals in the measured sludge samples did not exceed the limits set out by European legislation and were mainly associated with the two less-available fractions (27-28% as oxidizable metal and 44-50% as residual metal). However, metals as Co (64% in MS and 52% in FS samples), Mn (82% in MS and 79% in FS), Ni (32% in MS and 26% in FS) and Zn (79% in MS and 62% in FS) were present at important percentages as available forms. In addition, results showed a clear increase of the concentration of metals after sludge treatment in the proportion of two less-available fractions (oxidizable and residual metal).     

Bioconversion of industrial wastes: paint sludge from automotive manufacturing

The compostability of water-based paint sludge originating from the automotive industry was investigated. Six reactors were operated. Wastewater treatment sludge from the same industry was used as additional substrate, and corncob was used as a bulking agent. The level of paint sludge within the compost mixtures varied between 55 and 85%. All reactors yielded a temperature increase up to thermophilic phase levels (>?40 °C) for a minimum of 5 days, and organic matter and C/N losses were observed. BTEX concentrations decreased during composting. Nickel and tin levels in the final product exceeded the legal compost limits. The calorific value of the compost mixtures increased from 9532 to 18774 kJ/kg at the end of the composting process. It was seen that the process applied in this study can be utilized as a biodrying step before the usage of paint sludge at cement kilns as additional fuel.     

Effect of waste water treatment technology on the elimination of anionic surfactants

The concentrations of four anionic surfactants [i.e. linear alkylbenzene sulphonate (LAS), alcohol sulphate (AS), alcohol ether sulphate (AES), and secondary alkane sulphonate (SAS)], which are important from a commercial viewpoint were determined in influents and effluent of the Ratingen waste water treatment plant which is located in the vicinity of Düsseldorf, Germany. Elimination rates, which were calculated on the basis of influent and effluent concentrations, are in the range between 99.7 (LAS) and 99.99% (AES). Comparison of effluent concentrations (LAS 7–16 μg/l, AS and AES ≤ 1 μg/l) revealed that AS and AES were slightly better removed than LAS. Comparison of these data with results from a monitoring study carried out in 1995 at a time when the Ratingen works were working at the limit of their capacity revealed that LAS and dissolved organic carbon were effectively removed even under these conditions. ©     

Composting in small laboratory pilots: performance and reproducibility

Small-scale reactors (<10 l) have been employed in composting research, but few attempts have assessed the performance of composting considering the transformations of organic matter. Moreover, composting at small scales is often performed by imposing a fixed temperature, thus creating artificial conditions, and the reproducibility of composting has rarely been reported. The objectives of this study are to design an innovative small-scale composting device safeguarding self-heating to drive the composting process and to assess the performance and reproducibility of composting in small-scale pilots. The experimental setup included six 4-l reactors used for composting a mixture of sewage sludge and green wastes. The performance of the process was assessed by monitoring the temperature, O₂ consumption and CO₂ emissions, and characterising the biochemical evolution of organic matter. A good reproducibility was found for the six replicates with coefficients of variation for all parameters generally lower than 19%. An intense self-heating ensured the existence of a spontaneous thermophilic phase in all reactors. The average loss of total organic matter (TOM) was 46% of the initial content. Compared to the initial mixture, the hot water soluble fraction decreased by 62%, the hemicellulose-like fraction by 68%, the cellulose-like fraction by 50% and the lignin-like fractions by 12% in the final compost. The TOM losses, compost stabilisation and evolution of the biochemical fractions were similar to observed in large reactors or on-site experiments, excluding the lignin degradation, which was less important than in full-scale systems. The reproducibility of the process and the quality of the final compost make it possible to propose the use of this experimental device for research requiring a mass reduction of the initial composted waste mixtures.     

Composting of a solid olive-mill by-product ("alperujo") and the potential of the resulting compost for cultivating pepper under commercial conditions

A pollutant solid material called "alperujo" (AL), which is the main by-product from the Spanish olive oil industry, was composted with a cotton waste as bulking agent, and the compost obtained (ALC) was compared with a cattle manure (CM) and a sewage sludge compost (SSC) for use as organic amendment on a calcareous soil. The experiment was conducted with a commercial pepper crop in a greenhouse using fertigation. Composting AL involved a relatively low level of organic matter biodegradation, an increase in pH and clear decreases in the C/N and the fat, water-soluble organic carbon and phenol contents. The resulting compost, which was rich in organic matter and free of phytotoxicity, had a high potassium and organic nitrogen content but was low in phosphorus and micronutrients. The marketable yields of pepper obtained with all three organic amendments were similar, thus confirming the composting performance of the raw AL. When CM and SSC were used for soil amendment, the soil organic matter content was significantly reduced after cultivation, while it remained almost unchanged in the ALC-amended plots.     

A multivariate approach to the study of the composting process by means of analytical electrofocusing

Three blends formed by: agro-industrial waste, wastewater sewage sludge, and their mixture, blended with tree pruning as bulking agent, were composted over a 3-month period. During the composting process the blends were monitored for the main physical and chemical characteristics. Electrofocusing (EF) was carried out on the extracted organic matter. The EF profiles were analyzed by principal component analysis (PCA) in order to assess the suitability of EF to evaluate the stabilisation level during the composting process. Throughout the process, the blends showed a general shifting of focused bands, from low to high pH, even though the compost origin affected the EF profiles. If the EF profile is analyzed by dividing it into pH regions, the interpretation of the results can be affected by the origin of compost. A good clustering of compost samples depending on the process time was obtained by analyzing the whole profile by PCA. Analysis of EF results with PCA represents a useful analytical technique to study the evolution and the stabilisation of composted organic matter.     

Fractionation of heavy metals in sludge from anaerobic wastewater stabilization ponds in southern Spain

The analysis of heavy metals is a very important task to assess the potential environmental and health risk associated with the sludge coming from wastewater treatment plants (WWTPs). However, it is necessary to apply sequential extraction techniques to obtain suitable information about their bioavailability or toxicity. In this paper, a sequential extraction scheme according to the Standard, Measurements and Testing Programme of the European Commission was applied to sludge samples collected from ten anaerobic wastewater stabilization ponds (WSPs) located in southern Spain. Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti and Zn were determined in the sludge extracts by inductively coupled plasma atomic emission spectrometry. In relation to current international legislation for the use of sludge for agricultural purposes, none of the metal concentrations exceeded maximum permitted levels. Overall, heavy metals were mainly associated with the two less-available fractions (34% oxidizable metal and 55% residual metal). Only Mn and Zn showed the highest share of the available (exchangeable and reducible) fractions (25-48%).     

Biodegradability and Mechanical Properties of Poly(vinyl alcohol)-Based Blend Plastics Prepared Through Extrusion Method

Plastic blend materials consisting of poly(vinyl alcohol), glycerol and xanthan or gellan were prepared through laboratory extrusion. Their base mechanical properties were compared with the properties of poly(vinyl alcohol) foil and their biodegradability in soil, compost and both activated and anaerobic sludge were assessed. In samples with lower polysaccharide content (10–21 %w/w) the tensile strength of 15–20 MPa was found; the elongation at break of all blends was relatively close to the parameter of poly(vinyl alcohol) foil. The biodegradability levels of the blends tested corresponded to the content of natural components, and the mineralization of the samples with the highest carbohydrate proportion (42 %) reached 50–78 %, depending on the type of the environment. Complete biodegradation of all samples occurred in activated sludge.     

Waste paper and clinoptilolite as a bulking material with dewatered anaerobically stabilized primary sewage sludge (DASPSS) for compost production

Environmental problems associated with sewage sludge disposal have prompted strict legislative actions over the past few years. At the same time, the upgrading and expansion of wastewater treatment plants have greatly increased the volume of sludge generated. The major limitation of land application of sewage sludge compost is the potential for high heavy metal content in relation to the metal content of the original sludge. Composting of sewage sludge with natural zeolite (clinoptilolite) can enhance its quality and suitability for agricultural use. However, the dewatered anaerobically stabilized primary sewage sludge (DASPSS) contained a low concentration of humic substances (almost 2%), and the addition of the waste paper was necessary in order to produce a good soil conditioner with high concentrations of humics. The final results showed that the compost produced from DASPSS and 40-50% w/w of waste paper was a good soil fertilizer. Finally, in order to estimate the metal leachability of the final compost product, the generalized acid neutralization Capacity (GANC) procedure was used, and it was found that by increasing the leachate pH, the heavy metal concentration decreased. The application of the sequential chemical extraction indicated that metals were bound to the residual fraction characterized as a stabilize fractions.     

Reducing salinity and organic contaminants in the Pearl Harbor dredged material using soil amendments and plants

Phytoremediation is an emerging technique that can be used to economically remediate sites contaminated with trace elements and/or man‐made organic contaminants. This technique was used on Pearl Harbor (Oahu, Hawaii) dredged material (PHDM) containing polycyclic aromatic hydrocarbons (PAHs) and some heavy metals. The dredged material was first amended with a high‐calcium soil (Waialua Mollisol) and a biosolids‐based compost at different proportions to yield varying salinity levels. A mixture that yielded an electrical conductivity (EC, a measure of salinity) of the saturated paste extract of 15 to 20 dS/m was identified and used to evaluate the salt tolerance of five plant species. Relative germination and one‐month‐old biomass indicated that common bermuda grass (Cynodon dactylon), seashore paspalum (Paspalum vaginatum), beach pea (Vigna marina), and cow pea (Vigna unguiculata) can produce at least 40 percent of biomass of the control at an EC of approximately 18 dS/m, suggesting the four plants are relatively salt tolerant. In contrast, Desmodium intortum either did not germinate or died within two weeks after germination at the same salinity level. A subsequent greenhouse experiment, using mixtures of the PHDM (0 or 25 percent dry weight), organic amendments (10 percent leucaena green manure or biosolids‐based compost), and a Mollisol (65 or 90 percent dry weight) in 6‐liter pots containing 4 kilograms of material yielded the following results: (1) A combination of transplanted seashore paspalum, seeded bermuda grass, and seeded beach pea was effective in taking up sodium (Na), thereby reducing salinity and making the medium more amenable to diversified microbes and plants, which may be effective PAH degraders; (2) total PAH concentration was reduced by about 30 percent after three months of active plant growth, but degradation of individual PAH members varied significantly, however; (3) leguminous green manure, as a soil amendment, was more effective than compost for use in bio‐ and/or phytoremediations; and (4) soil amendments, when applicable, could supplement living plants in reducing organic contaminants, such as PAHs. © 2002 Wiley Periodicals, Inc.