In order to investigate phthalates in landfill leachates, four landfill simulation reactors, filled with municipal solid waste from a housing area, were studied. Plasticised polyvinyl chloride (PVC) was added to two of the reactors. Two reactors, one with and one without the additional PVC, were aerated for 3 months to achieve methanogenic conditions. The other two became acidogenic a few days after filling and closing. After approximately 3 years, the acidogenic waste became methanogenic. The leachates were analysed for phthalic acid diesters and their degradation products, phthalic acid monoesters and o-phthalic acid. The occurrence of monobenzyl phthalate (MbenzP) and mono(2-ethylhexyl) phthalate (MEHP) showed that the diesters, butylbenzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP), released from the PVC products had been transformed, and that they were not completely sorbed to particles or to the waste material. Monoesters were observed once methanogenic conditions were established. The monoesters and phthalic acid were present in concentrations several orders of magnitude higher than the diesters themselves. Our results show that it is important to include monoesters in studies of the fate of diesters. To date, monoesters have been neglected in investigations of organic pollutants in landfill leachates.

Phthalic acid diesters are additives in a variety of materials that can end up in landfills. ln a previous laboratory landfill simulation study, it was fouod that degradation intermediates such as phthalic acid monoesters and phthalic acid accumulate during the change from acidic to methanogenic conditions in municipal solid waste. In the present investigation, leachates from a series of fullscale youog landfill cells were analysed over time for dimethyl, diethyl, dibutyl, butylbenzyl, and di(2-ethylheliyl) phthalate (respectively designated DMP, DEP, DBP, BBP, and DEHP), and their corresponding monoesters monomethyl, monoethyl, monobutyl, monobenzyl, and mono(2 ethylhexyl) phthalate (MMP, MEP, MbutP, MbenzP, and MEHP, respectively), as well as ophthalic acid. One landfill cell was created in each of three consecutive years by deposition of the same type of waste in July and August. The pH, volatile fatty acids (VF As), and total orgaulc carbon (TOC) were measured to characterise development of the degradation phases in three landfill cells, which revealed early acidogenic to initial methanogenic stages. Analysis of the phthalate compounds showed that levels of the degradation products were below the detection limit in the acidogenic leachates but exceeded concentrations of their corresponding diesters in leachates from cells in the initial methanogenic phase. Maximmn and average concentrations of phthalic acid were 50 and 23 mg/L, respectively, and the corresponding values for the other phthalates were 430 and 27 µg/L. The concentrations of all phthalates decreased during the evolution of stable methanogenic conditions. The results were in aggrement with the landfill simulation reactor study.

Leachates from 17 different landfills in Europe were analysed with respect to phthalates, i.e. phthalic acid diesters (PAEs) and their degradation products phthalic acid monoesters (PMEs) and ortho-phthalic acid (PA). Diesters are ubiquitous and the human possible exposure and potential to human health and environment has put them in focus. The aim of this study was to elucidate whether monoesters and phthalic acid could be traced in landfill leachates and in what concentrations they may be found. The results showed that phthalates were present in the majority of the leachates investigated. The monoesters appeared from 1 to 20 μg/L and phthalic acid 2–880 μg/L (one divergent value of 19 mg phthalic acid/L). Their parental diesters were observed from 1 to 460 μg/L. These observed occurrences of degradation products, of all diesters studied, support that they are degraded under the landfill conditions covered by this study. Thus, we have presented strong evidences to conclude that microorganisms in landfills degrade diesters released from formulations in a variety of products, including polyvinyl chloride (PVC) species.

The distribution of a-phthalic acid and ten of its mono- and diesters in the leachate plume downgradient of an unlined landfill (Grindsted, Denmark) was mapped along an 80 m transect. A total of 27 groundwater samples were concentrated by solid-phase extraction (SPE) using a polystyrene divinylbenzene (PS-DVB) polymer. Elevated concentrations of DEP, MEP and phthalic acid were observed, with maxima of 1260, 231 and 51 µg/L, respectively. Generally, high concentrations were observed close to the landfill border and in the lower parts of the aquifer. At a distance of 50m from the landfill border, the concentrations of all the studied phthalates, including DEP, MEP and PA, had decreased to below the detection limits (1 µg/L ). The presence of the specific metabolite MEP and PA, at the landfill border and in the plume, indicates that in situ anaerobic degradation/transformation of DEP occurred both in and beneath the landfill, as well as in the leachate-contarninated soil profile. Our findings suggest that anaerobic degradation is a key process also in the aquifer at the Grindsted landfill site. Tills study emphasises that phthalates should be regarded as potential contaminants in aquifers.

Retention mechanisms of an unmodified and a hydroxylated polystyrene–divinylbenzene polymer were studied by solid-phase extraction of o-phthalic acid and some of its mono- and diesters from purified water and then analysing by GC–MS. The monoesters and phthalic acid were retained only when protonated (i.e. acidified with HCl to pH 0.9). Of all elution solvents tested, ethyl acetate gave the best overall recoveries (61–89%) with both polymers. Applicability to complex matrixes (e.g. acidogenic landfill leachates) was examined by introducing a washing step with acetone in acidified water (pH 0.9) to eliminate volatile fatty acids (C₂–C₆) from the cartridge. Finally, the method was tested on real samples.

The degradation of phthalic acid diesters may lead to formation of a-phthalic acid and phthalic acid monoesters. The ecotoxic properties of the monoesters have never been systematically investigated and concern has been raised that these degradation products may be more toxic than the diesters. Therefore, the aquatic toxicity of phthalic acid, 6 monoesters, and 5 diesters of a-phthalic acid was tested in three standardized toxicity tests using the bacteria Vibrio fischeri, the green algae Pseudokirchneriella subcapitata, and the crustacean Daphnia magna. The monoesters tested were monomethyl-, monoethyl-, monobutyl-, monobenzyl-, mono(2-ethylhexyl)-and monodecyl phthalate; while the diesters tested were dimethyl-, diethyl-, dibutyl-, butylbenzyl-, and di(2-ethylhexyl) phthalate. The compounds were tested in concentrations below the water solubility and concentrations were confirmed by chemical analyses. The EC₅₀-values for the three organisms ranged from 103 mg/L to >4710 mg/L for phthalic acid, and corresponding values for the monoesters ranged from 2.3 mg/L (monodecyl phthalate in bacteria test) to 4130 mg!L (monomethyl phtalate in bacteria test). Dhnethyl- and diethyl- phthalate were found to be the least toxic of the diesters (EC₅₀ from 26.2-377 mg/L) and the toxicity of the other diesters (butylbenzyland dibutyl phthalate) ranged from 0.96 mg/L to 7.74 mg/L. In general, the phthalate monoesters (degradation products) were less toxic than the corresponding diesters (mother compounds).