Assessment of polychlorinated dibenzo-p-dioxin and dibenzofuran emissions from a hazardous waste incineration plant using long-term sampling equipment

The aim of this work is to evaluate the performance of a continuous monitoring system for the analysis of the mass concentration of PCDD/Fs from stationary sources. Data was acquired from a modern, state of the art, hazardous waste thermal treatment plant for a period of more than 2 years using a commercial available continuous monitoring system. The study consisted of a total of 16 samples, collected in periods from 1 week to 2 months resulting in an average of 360 m³ sampled flue gas per sample. The study showed the system was able to confirm that for a period of more than 2 years the plant was complying with the limit of 0.1 ng I-TEQ/Nm³. In addition, the data showed the typical fingerprint of such installations which is useful for example in impact studies. Long-term samples were compared to five short-term samples (6 h) collected every 6 months during the study period. Principal component analysis was applied to PCDD/Fs obtained data as useful statistical tool to find out trends and similarities between different samples. Improvement in terms of representativeness of data was achieved through continuous assessment since the starts of the project. The obtained data was further used to determine the emission factor for this activity and the total annual PCDD/Fs release to the atmosphere.     

Effects of bioturbation on the fate of oil in coastal sandy sediments--an in situ experiment

Effects of bioturbation by the common lugworm Arenicola marina on the fate of oil hydrocarbons (alkanes and PAHs) were studied in situ during a simulated oil spill in a shallow coastal area of Roskilde fjord, Denmark. The fate of selected oil compounds was monitored during 120 d using GC-MS and bioturbation activity (feces production and irrigation) was measured regularly during the experiment and used as input parameters in a mechanistic model describing the effects of A. marina on the transport and degradation of oil compounds in the sediment. The chemical analytical data and model results indicated that A. marina had profound and predictable effects on the distribution, degradation and preservation of oil and that the net effect depended on the initial distribution of oil. In sediment with an oil contaminated subsurface-layer A. marina buried the layer deeper in the sediment which clearly enhanced oil persistence. Conversely, A. marina stimulated both the physical removal and microbial degradation of oil compounds in uniformly oil contaminated sediments especially in deeper sediment layers (10-20 cm below the surface), whereas the fate of oil compounds deposited in surface layers (0-5 cm) mainly was affected by removal processes induced by wave actions and other bioturbating infauna such as Nereis diversicolor, Corophium volutator and Hydrobia spp. present in the experimental plots.     

Polybrominated diphenyl ethers in food and associated human daily intake assessment considering bioaccessibility measured by simulated gastrointestinal digestion

The concentrations of PBDEs in 299 vegetable and animal-based food samples of 31 species, collected in Shanghai, China, and the bioaccessibility of PBDEs in part of the samples were determined. The PBDE concentrations ranged from 0 to 1245.4 pg g⁻¹ with animal-based food containing more PBDEs than vegetables. The bioaccessibility of PBDEs, determined by a method simulating human gastrointestinal digestion process, were from 2.6% to 39.9% in vegetables, and from 5.2% to 105.3% in animal-based food. For animal-based food, good correlations were observed between the bioaccessibility of PBDEs and the fat content, thus the fat content in animal-based food was able to be used to estimate the bioaccessibility of PBDEs. The total daily intake of PBDEs via ingestion of vegetables and animal-based food for an average Shanghai resident was estimated as 13 235.7 and 13 668.0 pg d⁻¹, respectively, but the amounts available for human absorption were reduced to 2674.4 and 4316.6 pg d⁻¹ after the PBDE bioaccessibility was considered. Finally, the contributions of different food groups to the total daily intake of PBDEs were evaluated. The results revealed that, when not considering the bioaccessibility of PBDEs, vegetables were the leading contributor (49.2%), followed by fish (34.0%). However, the sequence was reversed after the PBDE bioaccessibility was taken into account. The results indicated that human exposure to PBDEs via food ingestion might have been significantly overestimated and the exposure assessment could be misleading if the bioaccessibility of PBDEs was not considered.     

Dietary intake of hexabromocyclododecane diastereoisomers (α-, β-, and γ-HBCD) in the Belgian adult population

A study was performed to assess exposure of the Belgian population to HBCD diastereoisomers. Measurements of HBCD were performed by UPLC-MS/MS, on 45 composite samples from 5 major food groups: dairy (products), meat (products), eggs, fish (products) and a group of “other” products. The medium bound estimated average daily intake (EDI) of ΣHBCD in the Belgian population was 0.99 ng kg⁻¹ bw d⁻¹. The diastereoisomer contribution to the mean EDI showed a predominance of γ-HBCD at 67%, followed by α-HBCD at 25% and 8% for β-HBCD. These results are consistent with the pattern found in the two food groups contributing the most to the EDI: meat (products) and the group of “other” products. Anyway, it has to be noted that diastereomeric distribution of HBCD can change due to bioisomerisation in biological material. Levels of HBCD diastereoisomers found in Belgian food samples of animal origin were low in comparison with those found in other EU countries and the resulting EDI was substantially below the proposed thresholds.     

The effect of mercury on trees and their mycorrhizal fungi

The Oak Ridge Reservation, established in 1942, was the designated site for the construction of the atomic bomb. During a 20-year period from 1944 to 1963 radioactive and toxic chemical pollutants, especially mercury compounds were released into the surrounding waterways. Tree diversity and mycorrhizal presence and abundance were analyzed in the mercury-contaminated floodplains of East Fork Poplar Creek Oak Ridge (EFPC) (Tennessee). A subsequent greenhouse study was conducted to assess the phytotoxic effects of different mercuric solutions on Platanus occidentalis (American Sycamore), inoculated with soils from EFPC. Total soil mercury in the field had no effect on tree diversity. Organic species of mercury proved to be more toxic than inorganic species of mercury and soil inoculants from EFPC had no protective effects against Hg toxicity in our greenhouse study. Comparison of the effects of mercury contamination in our field and greenhouse studies was difficult due to uncontrolled factors.     

Wasteful waste-reducing policies? The impact of waste reduction policy instruments on collection and processing costs of municipal solid waste

We study the impact of some local policies aimed at municipal solid waste (MSW) reduction on the cost efficiency of MSW collection and disposal. We explicitly account for differences between municipalities in background conditions by using a bootstrapped version of the Data Envelopment Analysis methodology in combination with a matching technique. Using data on 299 municipalities in Flanders, Belgium, for the year 2003, our results indicate that municipalities that are member of a waste collection joint venture, or that subscribe to a voluntary agreement to reduce MSW at the highest ambition level, collect and process MSW more efficiently than other municipalities. Weekly instead of two-weekly waste collection, or using a weight-based pricing system appears to have no impact on efficiency. Our results show that aiming at MSW reduction does not lead to lower efficiency of public service provision, even on the contrary.     

A potential sanitary sewer overflow treatment technology: fixed-media bioreactors

Under certain conditions, sanitary sewer overflows (SSOs) containing raw wastewater may be discharged to public land and can contribute to environmental and public health issues. Although this problem has attracted the attention of local, state, and federal government and regulators, relatively little SSO abatement research has been published. This study used fixed-media bioreactors, a proven onsite technology in rural areas, to treat wet weather SSO wastewater and reduce its effects on the receiving water environment. The results of this 32-month laboratory study showed that fixed-media bioreactors, especially sand bioreactors, efficiently removed organic matter, solids, and nutrients during six-hour simulated SSO peak flows. Five-day biochemical oxygen demand (BODs) of the simulated SSO varied between 40 and 125 mg/L. The average effluent concentration of BOD5 was 13 mg/L in sand bioreactors at a hydraulic loading rate of 20.4 cm/h. In addition to having high hydraulic loadings, SSO events occur infrequently. This irregularity requires that treatment systems quickly start up and effectively treat wastewater after a period of no flow. This research found that an interval up to six months between two SSO peak flows did not affect the bioreactor performance. Based on this work, fixed-media bioreactors have the potential to reduce the effects of SSOs on the water environment by following proper design parameters and operation strategies. The pollution loading of approximately 18 g BODs/m2 x h is recommended for the efficient performance of sand bioreactors in the SSO treatment.