Food waste collection and recycling for value-added products: potential applications and challenges in Hong Kong

About 3600 tonnes food waste are discarded in the landfills in Hong Kong daily. It is expected that the three strategic landfills in Hong Kong will be exhausted by 2020. In consideration of the food waste management environment and community needs in Hong Kong, as well as with reference to the food waste management systems in cities such as Linköping in Sweden and Oslo in Norway, a framework of food waste separation, collection, and recycling for food waste valorization is proposed in this paper. Food waste can be packed in an optic bag (i.e., a bag in green color), while the residual municipal solid waste (MSW) can be packed in a common plastic bag. All the wastes are then sent to the refuse transfer stations, in which food waste is separated from the residual MSW using an optic sensor. On the one hand, the sorted food waste can be converted into valuable materials (e.g., compost, swine feed, fish feed). On the other hand, the sorted food waste can be sent to the proposed Organic Waste Treatment Facilities and sewage treatment works for producing biogas. The biogas can be recovered to produce electricity and city gas (i.e., heating fuel for cooking purpose). Due to the challenges faced by the value-added products in Hong Kong, the biogas is recommended to be upgraded as a biogas fuel for vehicle use. Hopefully, the proposed framework will provide a simple and effective approach to food waste separation at source and promote sustainable use of waste to resource in Hong Kong.     

The use of food wastes as feed ingredients for culturing grass carp (<Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>) in Hong Kong

Different types of food wastes, e.g., meats, bones, cereals, fruits, and vegetables, were collected from hotels in Hong Kong, mixed in different ratio, and processed into feed pellets (food wastes (FWs) A, B, and C) for feeding trials in aquaculture species. Grass carp fed with cereal-dominant feed (FW A) showed the best growth (in terms of specific growth rate, relative weight gain, and protein efficiency ratio), among all food waste feeds. However, the growth rates of food waste groups especially the meat product-contained feeds (FW B and FW C) were lower than the commercial feed, Jinfeng^® 613 formulation (control). The results indicated that grass carp utilized plant proteins better than animal proteins and preferred carbohydrate as a major energy source than lipid. The high-lipid content in feed containing meat products was also a possible reason for hindering growth and resulted high body lipid. It is suggested that lipid should be removed in the preparation of food waste feed or further investigations by implementing supplements, e.g., enzymes in feed to enhance lipid or protein utilization by fish. This utilization of food waste could be an effective and practical way to deal with these wastes in this densely populated city.     

Life cycle of PCBs and contamination of the environment and of food products from animal origin

This report gives a summary of the historic use, former management and current release of polychlorinated biphenyls (PCBs) in Germany and assesses the impact of the life cycle of PCBs on the contamination of the environment and of food products of animal origin. In Germany 60,000 t of PCBs were used in transformers, capacitors or as hydraulic oils. The use of PCB oils in these “closed applications”, has been banned in Germany in 2000. Thirty to 50% of these PCBs were not appropriately managed. In West Germany, 24,000 t of PCBs were used in open applications, mainly as additive (plasticiser, flame retardant) in sealants and paints in buildings and other construction. The continued use in open applications has not been banned, and in 2013, an estimated more than 12,000 t of PCBs were still present in buildings and other constructions. These open PCB applications continuously emit PCBs into the environment with an estimated release of 7–12 t per year. This amount is in agreement with deposition measurements (estimated to 18 t) and emission estimates for Switzerland. The atmospheric PCB releases still have an relevant impact on vegetation and livestock feed. In addition, PCBs in open applications on farms are still a sources of contamination for farmed animals. Furthermore, the historic production, use, recycling and disposal of PCBs have contaminated soils along the lifecycle. This legacy of contaminated soils and contaminated feed, individually or collectively, can lead to exceedance of maximum levels in food products from animals. In beef and chicken, soil levels of 5 ng PCB-TEQ/kg and for chicken with high soil exposure even 2 ng PCB-TEQ/kg can lead to exceedance of EU limits in meat and eggs. Areas at and around industries having produced or used or managed PCBs, or facilities and areas where PCBs were disposed need to be assessed in respect to potential contamination of food-producing animals. For a large share of impacted land, management measures applicable on farm level might be sufficient to continue with food production. Open PCB applications need to be inventoried and better managed. Other persistent and toxic chemicals used as alternatives to PCBs, e.g. short chain chlorinated paraffins (SCCPs), should be assessed in the life cycle for exposure of food-producing animals and humans.     

Life cycle and economic assessment of source-separated MSW collection with regard to greenhouse gas emissions: a case study in China

In China, the continuously increasing amount of municipal solid waste (MSW) has resulted in an urgent need for changing the current municipal solid waste management (MSWM) system based on mixed collection. A pilot program focusing on source-separated MSW collection was thus launched (2010) in Hangzhou, China, to lessen the related environmental loads. And greenhouse gas (GHG) emissions (Kyoto Protocol) are singled out in particular. This paper uses life cycle assessment modeling to evaluate the potential environmental improvement with regard to GHG emissions. The pre-existing MSWM system is assessed as baseline, while the source separation scenario is compared internally. Results show that 23 % GHG emissions can be decreased by source-separated collection compared with the base scenario. In addition, the use of composting and anaerobic digestion (AD) is suggested for further optimizing the management of food waste. 260.79, 82.21, and ?86.21 thousand tonnes of GHG emissions are emitted from food waste landfill, composting, and AD, respectively, proving the emission reduction potential brought by advanced food waste treatment technologies. Realizing the fact, a modified MSWM system is proposed by taking AD as food waste substitution option, with additional 44 % GHG emissions saved than current source separation scenario. Moreover, a preliminary economic assessment is implemented. It is demonstrated that both source separation scenarios have a good cost reduction potential than mixed collection, with the proposed new system the most cost-effective one.     

Valorization of spent coffee grounds recycling as a potential alternative fuel resource in Turkey: An experimental study

In this study, recycling of spent coffee grounds (SCG) as a potential feedstock for alternative fuel production and compounds of added value in Turkey was assessed. The average oil content was found (≈ 13% w/w). All samples (before and after extraction) were tested for scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), calorific value, surface analysis and porosity, Fourier transform infrared (FT-IR), and elemental analysis to assess their potential towards fuel properties. Elemental analysis indicated that carbon represents the highest percentages (49.59% and 46.42%, respectively), followed by nitrogen (16.7% and 15.5%), hydrogen (6.74% and 6.04%), and sulfur (0.851% and 0.561%). These results indicate that SCG can be utilized as compost, as it is rich in nitrogen. Properties of the extracted oil were examined, followed by biodiesel production. The quality of biodiesel was compared with American Society for Testing and Materials (ASTM) D6751 standards, and all the properties complied with standard specifications. The fatty acid compositions were analyzed by gas chromatography. It was observed that coffee waste methyl ester (CWME) is mainly composed of palmitic (35.8%) and arachidic (44.6%) acids, which are saturated fatty acids. The low degree of unsaturation provides an excellent oxidation stability (10.4 hr). CWME has also excellent cetane number, higher heating value, and iodine value with poor cold flow properties. The studies also investigated blending of biodiesel with Euro diesel and butanol. Following this, a remarkable improvement in cloud and pour points of biodiesel was obtained. Spent coffee grounds after oil extraction is an ideal material for garden fertilizer, feedstock for ethanol, biogas production, and as fuel pellets. The outcome of such research work produces valuable insights on the recycling importance of SCG in Turkey.

Implications: Coffee is a huge industry, and coffee has been widely used due to its refreshing properties. This industry generates large quantities of waste. Therefore, recycling of spent coffee grounds for producing alternative fuels and compounds of added value is crucial. Elemental analysis indicated that coffee waste can be utilized as compost, as it is rich in nitrogen. Coffee waste after oil extraction is an ideal feedstock for ethanol and biogas production, garden fertilizer, and as fuel pellets. The low degree of unsaturation provides excellent oxidation stability. Its biodiesel has also excellent cetane number, higher heating value, and lower iodine value.     

Evaluation of PCB sources and releases for identifying priorities to reduce PCBs in Washington State (USA)

Polychlorinated biphenyls (PCBs) are ubiquitously distributed in the environment and produce multiple adverse effects in humans and wildlife. As a result, the purpose of our study was to characterize PCB sources in anthropogenic materials and releases to the environment in Washington State (USA) in order to formulate recommendations to reduce PCB exposures. Methods included review of relevant publications (e.g., open literature, industry studies and reports, federal and state government databases), scaling of PCB sources from national or county estimates to state estimates, and communication with industry associations and private and public utilities. Recognizing high associated uncertainty due to incomplete data, we strived to provide central tendency estimates for PCB sources. In terms of mass (high to low), PCB sources include lamp ballasts, caulk, small capacitors, large capacitors, and transformers. For perspective, these sources (200,000–500,000 kg) overwhelm PCBs estimated to reside in the Puget Sound ecosystem (1500 kg). Annual releases of PCBs to the environment (high to low) are attributed to lamp ballasts (400–1500 kg), inadvertent generation by industrial processes (900 kg), caulk (160 kg), small capacitors (3–150 kg), large capacitors (10–80 kg), pigments and dyes (0.02–31 kg), and transformers (<2 kg). Recommendations to characterize the extent of PCB distribution and decrease exposures include assessment of PCBs in buildings (e.g., schools) and replacement of these materials, development of Best Management Practices (BMPs) to contain PCBs, reduction of inadvertent generation of PCBs in consumer products, expansion of environmental monitoring and public education, and research to identify specific PCB congener profiles in human tissues.     

Projected future climate change and Baltic Sea ecosystem management

Climate change is likely to have large effects on the Baltic Sea ecosystem. Simulations indicate 2–4 °C warming and 50–80 % decrease in ice cover by 2100. Precipitation may increase ~30 % in the north, causing increased land runoff of allochthonous organic matter (AOM) and organic pollutants and decreased salinity. Coupled physical–biogeochemical models indicate that, in the south, bottom-water anoxia may spread, reducing cod recruitment and increasing sediment phosphorus release, thus promoting cyanobacterial blooms. In the north, heterotrophic bacteria will be favored by AOM, while phytoplankton production may be reduced. Extra trophic levels in the food web may increase energy losses and consequently reduce fish production. Future management of the Baltic Sea must consider the effects of climate change on the ecosystem dynamics and functions, as well as the effects of anthropogenic nutrient and pollutant load. Monitoring should have a holistic approach, encompassing both autotrophic (phytoplankton) and heterotrophic (e.g., bacterial) processes.     

A comparative study on per capita waste generation according to a waste collecting system in Korea

As cities are becoming increasingly aware of problems related to conventional mobile collection systems, automated pipeline-based vacuum collection (AVAC) systems have been introduced in some densely populated urban areas. The reasons are that in addition to cost savings, AVAC systems can be efficient, hygienic, and environmentally friendly. Despite difficulties in making direct comparisons of municipal waste between a conventional mobile collection system and an AVAC system, it is meaningful to measure the quantities in each of these collection methods either in total or on a per capita generation of waste (PCGW, g/(day*capita)) basis. Thus, the aim of this study was to assess the difference in per capita generation of household waste according to the different waste collection methods in Korea. Observations on household waste show that there were considerable differences according to waste collection methods. The value of per capita generation of food waste (PCGF) indicates that a person in a city using AVAC produces 60 % of PCGF (109.58 g/(day*capita)), on average, compared with that of a truck system (173.10 g/(day*capita)) as well as 23 %p less moisture component than that with trucks. The value of per capita generation of general waste (PCGG) in a city with an AVAC system showed 147.73 g/(day*capita), which is 20 % less than that with trucks delivered (185 g/(day*capita)). However, general waste sampled from AVAC showed a 35 %p increased moisture content versus truck delivery.     

Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment Cores of Selected Creeks in Delta State,Nigeria

The spatial and seasonal distribution and concentrations of polycyclic aromatic hydrocarbons (PAHs) were investigated in core sediments of Ubeji, Ifie, and Egbokodo creeks in the Niger Delta, Nigeria. A total of 222 core sediment samples were collected during the wet season (August 2010) and the dry season (January 2011). The samples were dried, Soxhlet extracted, fractionated, and injected into a gas chromatograph with flame ionization detector (GC-FID). The concentrations of PAHs ranged from not detected to 2,654 μg/kg (wet season) and not detected to 3,513 μg/kg (dry season). In general, the concentrations of PAHs for a number of stations in this study are comparable to sites with high anthropogenic activities in the Niger Delta. The toxicity risk assessment based on the total BaP equivalent quotient of the seven carcinogenic PAHs (BaA, Chry, BbF, BkF, BaP, DBA, and Iper) was 97.416 μg/kg and did not exceed the method B cleanup level for benzo(a)pyrene (137 μg/kg), according to toxic equivalency factors, which implied that PAHs in sediments of the present study currently have minimal adverse effects. This study provided information on the concentrations and profiles of PAHs sediment cores, which is useful for source diagnosis, environmental quality management, contamination history, and environmental forensic studies.     

Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes

Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m³ tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH?<?2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1–5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5 % w/w) which were more basic (pH?>?9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation.     

Electricity generation from landfill gas in Turkey

Landfill gas (LFG)-to-energy plants in Turkey were investigated, and the LFG-to-energy plant of a metropolitan municipal landfill was monitored for 3 years. Installed capacities and actual gas engine working hours were determined. An equation was developed to estimate the power capacity for LFG-to-energy plants for a given amount of landfilled waste. Monitoring the actual gas generation rates enabled determination of LFG generation factors for Turkish municipal waste. A significant relationship (R = 0.524, p < 0.01, two-tailed) was found between the amounts of landfilled waste and the ambient temperature, which can be attributed to food consumption and kitchen waste generation behaviors influenced by the ambient temperature. However, no significant correlation was found between the ambient temperature and the generated LFG. A temperature buffering capacity was inferred to exist within the landfill, which enables the anaerobic reactions to continue functioning even during cold seasons. The average LFG and energy generation rates were 45 m³ LFG/ton waste landfilled and 0.08 MWhr/ton waste landfilled, respectively. The mean specific LFG consumption for electricity generation was 529 ± 28 m³/MWhr.

Implications: The paper will be useful for local authorities who need to manage municipal waste by using landfills. The paper will also be useful for investors who want to evaluate the energy production potential of municipal wastes and the factors affecting the energy generation process mostly for economical purposes. Landfills can be regarded as energy sources and their potentials need to be investigated. The paper will also be useful for policymakers dealing with energy issues. The paper contains information on real practical data such as engine working hours, equation to estimate the necessary power for a given amount of landfilled waste, and son on.     

Hexabromocyclododecanes in soils and plants from a plastic waste treatment area in North China: occurrence,diastereomer- and enantiomer-specific profiles,and metabolization

Plastic waste is a source of organic contaminants such as hexabromocyclododecanes (HBCDs). HBCDs have been found to cause developmental and reproductive toxicity; it is important to investigate the occurrence and metabolization of HBCDs in the soil environments with plastic waste contamination. This work analyzed HBCDs and their metabolites in soil and plant samples collected from Xinle and Dingzhou—the major plastic waste recycling centers in North China. Results showed that total HBCD concentrations in soils followed the order: plastic waste treatment site (11.0–624 ng/g) > roadside (2.96–85.4 ng/g) ≥ farmland (8.69–55.5 ng/g). HBCDs were detected in all the plant samples with total concentrations ranging from 3.47 to 23.4 ng/g. γ-HBCD was the dominant congener in soils, while α-HBCD was preferentially accumulated in plants. Compositions of HBCD isomers in soils and plants were significantly different (P < 0.05) among sampling sites and among plant species. HBCDs in farmland soil and all plant samples exhibited high enantio-selectivity based on the enantiomeric fractions (EFs). Furthermore, metabolites of pentabromocyclododecenes (PBCDEs) were frequently identified in soils, and mono-OH-HBCDs were the most common ones in plants. This study for the first time provides evidences of HBCD contamination in the soil-plant system caused by plastic waste, their stereo-selectivity, and metabolization behavior, improving our understanding of the environmental behavior and fate of HBCDs.     

Harnessing dark fermentative hydrogen from pretreated mixture of food waste and sewage sludge under sequencing batch mode

Food waste and sewage sludge are the most abundant and problematic organic wastes in any society. Mixture of these two wastes may provide appropriate substrate condition for dark fermentative biohydrogen production based on synergistic mutual benefits. This work evaluates continuous hydrogen production from the cosubstrate of food waste and sewage sludge to verify mechanisms of performance improvement in anaerobic sequencing batch reactors. Volatile solid concentration and mixing ratio of food waste and sludge were adjusted to 5 % and 80:20, respectively. Five different hydraulic retention times (HRT) of 36, 42, 48, 72, and 108 h were tested using anaerobic sequencing batch reactors to find out optimal operating condition. Results show that the best performance was achieved at HRT 72 h, where the hydrogen yield, the hydrogen production rate, and hydrogen content were 62.0 mL H₂/g VS, 1.0 L H₂/L/day, and ~50 %, respectively. Sufficient solid retention time (143 h) and proper loading rate (8.2 g COD/L/day as carbohydrate) at HRT 72h led to the enhanced performance with better hydrogen production showing appropriate n-butyrate/acetate (B/A) ratio of 2.6. Analytical result of terminal-restriction fragment length polymorphism revealed that specific peaks associated with Clostridium sp. and Bacillus sp. were strongly related to enhanced hydrogen production from the cosubstrate of food waste and sewage sludge.     

Biological effects of ammonia released from a composting plant assessed with lichens

In this study, we investigated whether ammonia emissions from industrial composting of organic waste may influence the surrounding environment, using lichens as bioindicators. To this purpose, samples of N-tolerant and N-sensitive lichens, namely Xanthoria parietina and Evernia prunastri, were transplanted for 1–3 months along transects at increasing distance (0–400 m) from a composting facility in Tuscany, Italy. Atmospheric concentrations of ammonia were measured using passive samplers. The physiological response of lichen transplants was investigated by means of the photosynthetic efficiency (measured as chlorophyll a fluorescence emission), the integrity of cell membranes (measured as electrolyte leakage), and sample viability (measured as enzymatic activity of dehydrogenase). Epiphytic lichen communities were investigated using biodiversity indices. The results showed decreasing concentrations of ammonia, from 48.7 μg/m³ at the composting facility to 2.7 μg/m³ at 400 m. The N-tolerant X. parietina was not affected and some physiological parameters even showed a higher performance, while the N-sensitive E. prunastri showed a reduced performance with increasing atmospheric concentrations approaching the source. A shift from lichen communities composed by meso-acidophilous species (actual condition) to more nitrophilous communities in the near future, approaching the composting facility is suggested. It is concluded that lichens can provide useful data for decision-makers to establish correct science-based environmentally sustainable waste management policies.     

Evaluating levels and health risk of heavy metals in exposed workers from surgical instrument manufacturing industries of Sialkot,Pakistan

The study aimed to monitor heavy metal (chromium, Cr; cadmium, Cd; nickel, Ni; copper, Cu; lead, Pb; iron, Fe; manganese, Mn; and zinc, Zn) footprints in biological matrices (urine, whole blood, saliva, and hair), as well as in indoor industrial dust samples, and their toxic effects on oxidative stress and health risks in exposed workers. Overall, blood, urine, and saliva samples exhibited significantly higher concentrations of toxic metals in exposed workers (Cr; blood 16.30 μg/L, urine 58.15 μg/L, saliva 5.28 μg/L) than the control samples (Cr; blood 5.48 μg/L, urine 4.47 μg/L, saliva 2.46 μg/L). Indoor industrial dust samples also reported to have elevated heavy metal concentrations, as an example, Cr quantified with concentration of 299 mg/kg of dust, i.e., more than twice the level of Cr in household dust (136 mg/kg). Superoxide dismutase (SOD) level presented significant positive correlation (p?≤?0.01) with Cr, Zn, and Cd (Cr?>?Zn?>?Cd) which is an indication of heavy metal’s associated raised oxidative stress in exposed workers. Elevated average daily intake (ADI) of heavy metals resulted in cumulative hazard quotient (HQ) range of 2.97–18.88 in workers of different surgical units; this is an alarming situation of health risk implications. Principal component analysis-multiple linear regression (PCA-MLR)-based pie charts represent that polishing and cutting sections exhibited highest metal inputs to the biological and environmental matrices than other sources. Heavy metal concentrations in biological matrices and dust samples showed a significant positive correlation between Cr in dust, urine, and saliva samples. Current study will help to generate comprehensive base line data of heavy metal status in biomatrices and dust from scientifically ignored industrial sector. Our findings can play vital role for health departments and industrial environmental management system (EMS) authorities in policy making and implementation.     

Impact of treated urban wastewater for reuse in agriculture on crop response and soil ecotoxicity

The scarcity of freshwater resources is a serious problem in arid regions, such as Tunisia, and marginal quality water is gradually being used in agriculture. This study aims to study the impact of treated urban wastewater for reuse in agriculture on the health of soil and food crops. The key findings are that the effluents of Sfax wastewater treatment plant (WWTP) did not meet the relevant guidelines, therefore emitting a range of organic (e.g., up to 90 mg L^?1 COD and 30 mg L^?1 BOD₅) and inorganic pollutants (e.g., up to 0.5 mg L^?1 Cu and 0.1 mg L^?1 Cd) in the receiving aquatic environments. Greenhouse experiments examining the effects of wastewater reuse on food plants such as tomato, lettuce, and radish showed that the treated effluent adversely affected plant growth, photosynthesis, and antioxidant enzyme contents. However, the pollution burden and biological effects on plants were substantially reduced by using a 50 % dilution of treated sewage effluent, suggesting the potential of reusing treated effluent in agriculture so long as appropriate monitoring and control is in place.     

Upgrading food wastes by means of bromelain and papain to enhance growth and immunity of grass carp (<Emphasis Type="Italic">Ctenopharyngodon idella</Emphasis>)

The fast growing of global aquaculture industry accompanied with increasing pressure on the supply and price of traditional feed materials (e.g., fish meal and soy bean meal). This circumstance has urged the need to search alternative sources of feed stuff. Food waste was used as feed stuff in rearing fish which possess substantial protein and lipid. Grass carp are major species reared in Hong Kong with lower nutritional requirements; it is also an ideal species for investigating the feasibility of using food waste as fish feeds for local aquaculture industry. The growth and immunity, reflected by total protein, total immunologlobulin (IgI), and nitroblue tetrazolium (NBT) activity of grass carp blood, were depressed when feeding with food waste feeds without enzymes. However, the supplementation of bromelain and papain in fish feed enhanced the efficient use of food waste by grass carp, which in turn improved the fish immunity. The present results indicated that the addition of those enzymes could enhance the feed utilization by fish and hematological parameters of grass carp, and the improvement on growth and immunity superior to the control (commercial feed) was observed with the addition of bromelain and papain supplement. Addition of 1 and 2 % mixture of bromelain and papain could significantly enhance the lipid utilization in grass carp.     

Accelerated carbonation of wood combustion ash for CO<Subscript>2</Subscript> removal from gaseous streams and storage in solid form

In this work, ash generated by the combustion of wood in a central heating plant was used to remove and permanently store by accelerated carbonation CO₂ contained in a gas mixture simulating biogas. The process was studied as an alternative treatment to the ones currently available on the market for biogas upgrading. The process was investigated at laboratory scale by setting up a facility for directly contacting the wood ash and the synthetic biogas in a fixed bed reactor. The process was able to completely remove CO₂ during its initial phase. After about 30 h, CO₂ started to appear again in the outlet stream and its concentration rapidly increased. The specific CO₂ uptake achieved in solid carbonate form was of about 200 g/kg of dry wood ash. This value is an order of magnitude higher than the ones found for waste incineration bottom ash carrying out similar experiments. The difference was ascribed to the physicochemical properties of the ash, characterized by a fine particle size (d₅₀ <?0.2 mm) and high content of reactive phases with CO₂ (e.g., Ca hydroxides). The leaching behavior of the wood ash was examined before and after the accelerated carbonation process showing that the release of several elements was lower after the treatment; Ba leaching in particular decreased by over two orders of magnitude. However, the release of the critical elements for the management of this type of residues (especially Cr and sulfates) appeared not to be significantly affected, while V leaching increased.     

Monitoring OH-PCBs in PCB transport worker’s urine as a non-invasive exposure assessment tool

In this study, we analyzed hydroxylated polychlorinated biphenyls (OH-PCBs) in urine of both PCB transport workers and PCB researchers. A method to monitor OH-PCB in urine was developed. Urine was solid-phase extracted with 0.1% ammonia/ methanol (v/v) and glucuronic acid/sulfate conjugates and then decomposed using β-glucuronidase/arylsulfatase. After alkaline digestion/derivatization, the concentration of OH-PCBs was determined by HRGC/HRMS-SIM. In the first sampling campaign, the worker’s OH-PCB levels increased several fold after the PCB waste transportation work, indicating exposure to PCBs. The concentration of OH-PCBs in PCB transport workers’ urine (0.55~11 μg/g creatinine (Cre)) was higher than in PCB researchers’ urine (< 0.20 μg/g Cre). However, also a slight increase of OH-PCBs was observed in the researchers doing the air sampling at PCB storage area. In the second sampling, after recommended PCB exposure reduction measures had been enacted, the worker’s PCB levels did not increase during handling of PCB equipment. This suggests that applied safety measures improved the situation. Hydroxylated trichlorobiphenyls (OH-TrCBs) were identified as a major homolog of OH-PCBs in urine. Also, hydroxylated tetrachlorobiphenyls (OH-TeCBs) to hydroxylated hexachlorobiphenyls (OH-HxCBs) were detected. For the sum of ten selected major indicators, a strong correlation to total OH-PCBs were found and these can possibly be used as non-invasive biomarkers of PCB exposure in workers managing PCB capacitors and transformer oils. We suggest that monitoring of OH-PCBs in PCB management projects could be considered a non-invasive way to detect exposure. It could also be used as a tool to assess and improve PCB management. This is highly relevant considering the fact that in the next 10 years, approx. 14 million tons of PCB waste need to be managed. Also, the selected populations could be screened to assess whether exposure at work, school, or home has taken place.