Chantal Block

Automotive shredder residue (ASR): Reviewing its production from end-of-life vehicles (ELVs) and its recycling, energy or chemicals’ valorisation

ASR is in Europe classified as hazardous waste. Both the stringent landfill legislation and the objectives/legislation related to ELV treatment of various countries, will limit current landfilling practice and impose an increased efficiency of the recovery and recycling of ELVs. The present paper situates ASR within the ELV context. Primary recovery techniques recycle up to 75% of the ELV components; the remaining 25% is called ASR. Characteristics of ASR and possible upgrading by secondary recovery techniques are reviewed. The latter techniques can produce a fuel- or fillergrade ASR, however with limitations as discussed. A further reduction of ASR to be disposed of calls upon (co-)incineration or the use of thermo-chemical processes, such as pyrolysis or gasification. The application in waste-to-energy plants, in cement kilns or in metallurgical processes is possible, with attention to the possible environmental impact: research into these impacts is discussed in detail. Pyrolysis and gasification are emerging technologies: although the sole use of ASR is debatable, its mixing with other waste streams is gradually being applied in commercial processes. The environmental impacts of the processes are acceptable, but more supporting data are needed and the advantage over (co-)incineration remains to be proven.

Mass balance for POPs in hazardous and municipal solid waste incinerators

The amount of different persistent organic pollutants (POPs) in the input of waste incinerators was compared to that in the output. Three cases were considered: a rotary kiln incinerating hazardous waste, a grate furnace incinerating municipal solid waste (MSW) and the same grate furnace co-incinerating plastics of waste of electrical and electronic equipment (WEEE) and automotive shredder residue (ASR) with MSW. The mass balance for PCBs in the rotary kiln indicates that these POPs are destroyed effectively during incineration. The grate furnace can be a sink or source of PCDD/Fs and PCBs depending on the concentrations in the incinerated waste. In order to compare the total amount of POPs in input and output, a methodology was developed whereby the amount of POPs was weighed according to minimal risk doses (MRDs) or cancer potency factors. For both incinerators the PCDD/Fs, PCBs and polyaromatic hydrocarbons (PAHs) are the main contributors to total weighed POP output. In MSW, the PCDD/Fs, PBDD/Fs and polybrominated diphenylethers (PBDEs) are the main contributors to the weighed POP input. The ratios of the weighed POP-input over -output clearly indicate that the rotary kiln incinerating hazardous waste is a weighed POP sink. The grate furnace incinerating MSW is a weighed POP sink or source depending on the POP-concentrations in the waste, but the difference between output and input is rather limited. When e.g. ASR and plastics of WEEE, containing high concentrations of PBDEs and PCBs, are co-incinerated in the grate furnace, it is clearly a weighed POP sink.

Destruction and formation of dioxin-like PCBs in dedicated full scale waste incinerators

Destruction and formation of dioxin-like PCBs in full scale waste incinerators is studied by analysing input waste streams and boiler and fly ash of a grate furnace incinerator (GFI) incinerating MSW, of a Fluidised Bed Combustor (FBC) incinerating a mix of 50% sludge, 25% refuse derived fuel (RDF) and 25% automotive shredder residue (ASR) and of a rotary kiln incinerator (RKI) incinerating hazardous waste. The dioxin-like PCB fingerprints of the waste inputs show that PCB oils Aroclor 1242 and Aroclor 1254 late are the major dioxin-like PCB contamination source of sludge, RDF and ASR. The dioxin-like PCB fingerprints of the waste inputs are clearly different from the fingerprints of the outputs, i.e. boiler and fly ash, indicating that in full scale waste incinerators dioxin-like PCBs in the input waste are destroyed and other dioxin-like PCBs are newly formed in the post combustion zone. The dioxin-like PCB fingerprint of boiler and fly ash of all three incinerators corresponds well to the fly ash fingerprint obtained in lab scale de novo synthesis experiments, indicating that dioxin-like PCBs are mainly formed through this mechanism. The high PCB concentration in the input waste mix of the RKI does not promote the formation of dioxin-like PCBs through precursor condensation.

Recycling of spent adsorbents for oxyanions and heavy metal ions in the production of ceramics

Spent adsorbents for oxyanion forming elements and heavy metals are classified as hazardous materials and they are typically treated by stabilization/solidification before landfilling. The use of lime or cement for stabilization/solidification entails a high environmental impact and landfilling costs are high. This paper shows that mixing spent adsorbents in the raw material for the production of ceramic materials is a valuable alternative to stabilize oxyanion forming elements and heavy metals. The produced ceramics can be used as construction material, avoiding the high economic and environmental impact of stabilization/solidification followed by landfilling. To study the stabilization of oxyanion forming elements and heavy metals during the production process, two series of experiments were performed. In the first series of experiments, the main pollutant, Mo was adsorbed onto iron-based adsorbents, which were then mixed with industrial sludge (3 w/w%) and heated at 1100°C for 30 min. Mo was chosen, as this element is easily adsorbed onto iron-based adsorbents and it is the element that is the most difficult to stabilize (i.e. the highest temperatures need to be reached before the concentrations in the leachate are reduced). Leaching concentration from the 97/3 sludge/adsorbent mixture before heating ranged between 85 and 154 mg/kg; after the heating process they were reduced to 0.42-1.48 mg/kg. Mo was actually stabilized, as the total Mo concentration after addition was not affected by the heat treatment. In the second series of experiments, the sludge was spiked with other heavy metals and oxyanion forming elements (Cr, Ni, Cu, Zn, As, Cd and Pb) in concentrations 5 times higher than the initial concentrations; after heat treatment the leachate concentrations were below the regulatory limit values. The incorporation of spent adsorbents in ceramic materials is a valuable and sustainable alternative to the existing treatment methods, saving raw materials in the ceramics production process and avoiding the use of stabilizing agents. Besides, spent adsorbents added to the raw material for ceramic products, may improve their aesthetic and structural properties.

Assessment of the impact on human health of industrial emissions to air: does the result depend on the applied method?

The impact on human health of substances emitted to air by the Flemish industry was calculated with characterization factors (CFs) provided by the CML, Eco-indicator 99, EPS, EDIP and USEtox impact assessment methods. A comparison of the results pointed out that the choice of the CFs can greatly influence conclusions on the trend of the impact over time and on the relative contribution of the individual substances. If the impact on human health of organic substances and heavy metals was assessed separately, the differences between methods were less pronounced. In this case, the impacts on human health obtained by simply dividing the emitted masses of substances by the respective minimal risk concentrations or minimal risk doses, were comparable to those calculated with the CFs of the model-based methods.

Toward a Carbon Dioxide Neutral Industrial Park

The industrial park of Herdersbrug (Brugge, Flanders, Belgium) comprises 92 small and medium‐sized enterprises, a waste‐to‐energy incinerator, and a power plant (not included in the study) on its site. To study the carbon dioxide (CO) neutrality of the park, we made a park‐wide inventory for 2007 of the CO emissions due to energy consumption (electricity and fossil fuel) and waste incineration, as well as an inventory of the existing renewable electricity and heat generation. The definition of CO neutrality in Flanders only considers CO released as a consequence of consumption or generation of electricity, not the CO emitted when fossil fuel is consumed for heat generation. To further decrease or avoid CO emissions, we project and evaluate measures to increase renewable energy generation. The 21 kilotons (kt) of CO emitted due to electricity consumption are more than compensated by the 25 kt of CO avoided by generation of renewable electricity. Herdersbrug Industrial Park is thus CO neutral, according to the definition of the Flemish government. Only a small fraction (6.6%) of the CO emitted as a consequence of fossil fuel consumption (heat generation) and waste incineration is compensated by existing and projected measures for renewable heat generation. Of the total CO emission (149 kt) due to energy consumption (electricity + heat generation) and waste incineration on the Herdersbrug Industrial Park in 2007, 70.5% is compensated by existing and projected renewable energy generated in the park. Forty‐seven percent of the yearly avoided CO corresponds to renewable energy generated from waste incineration and biomass fermentation.

Environmental impact of incineration of calorific industrial waste: Rotary kiln vs. cement kiln

Rotary kiln incinerators and cement kilns are two energy intensive processes, requiring high temperatures that can be obtained by the combustion of fossil fuel. In both processes, fossil fuel is often substituted by high or medium calorific waste to avoid resource depletion and to save costs. Two types of industrial calorific waste streams are considered: automotive shredder residue (ASR) and meat and bone meal (MBM). These waste streams are of current high interest: ASR must be diverted from landfill, while MBM can no longer be used for cattle feeding. The environmental impact of the incineration of these waste streams is assessed and compared for both a rotary kiln and a cement kiln. For this purpose, data from an extensive emission inventory is applied for assessing the environmental impact using two different modeling approaches: one focusing on the impact of the relevant flows to and from the process and its subsystems, the other describing the change of environmental impact in response to these physical flows. Both ways of assessing emphasize different aspects of the considered processes. Attention is paid to assumptions in the methodology that can influence the outcome and conclusions of the assessment. It is concluded that for the incineration of calorific wastes, rotary kilns are generally preferred. Nevertheless, cement kilns show opportunities in improving their environmental impact when substituting their currently used fuels by more clean calorific waste streams, if this improvement is not at the expense of the actual environmental impact.

Adsorption of Oxyanions from Industrial Wastewater using Perlite-Supported Magnetite.

Most studies on oxyanion adsorption focus on their removal from synthetic solutions. It is often claimed that the considered adsorbents can be used to treat real (industrial) wastewaters, but this is seldom tested. Perlite-supported magnetite was characterized first by determining its specific surface area, magnetite content and by examining the coating. Tests on a synthetic solution showed that at the ideal pH values (pH 3 to 5), the order of adsorption is Mo(VI) > As(V) > Sb(V) > Cr(VI) > Se(VI). Most oxyanions can be removed for more than 75% with an adsorbent dosage of 1 g/l. Furthermore, perlite-supported magnetite has a higher removal efficiency for oxyanions than commercially available adsorbents and comparable adsorbents described in literature. Perlite-supported magnetite is suitable for treating real wastewaters: it can remove several oxyanions simultaneously from the considered industrial wastewater, but the adsorption order changes due to the presence of interfering anions.

Mo, Sb and Se Removal from Scrubber Effluent of a Waste Incinerator

Common physicochemical treatment of industrial wastewater is not very efficient regarding the removal of the oxyanion forming elements selenium, molybdenum and antimony. An industrial case is described where effluents from the wet treatment of flue gases from a rotary kiln for the incineration of industrial waste, contain variable amounts of the elements mentioned. The effluent of the scrubbers is neutralized, coagulated and flocculated. Mercury is removed by precipitation with TMT. The installation shows satisfactory results, complying with the regulations for common cations. The effluent of the settling tank still contains variable concentrations of selenium, molybdenum and antimony and the overall removal efficiency is not reproducible for these elements. Laboratory experiments are presented for the removal by coprecipitation and the results are discussed. Possible treatment methods are selected and evaluated in a matrix that may help in the selection of methods for the simultaneous removal of oxyanion forming elements.

Sustainable Waste Processing In A Grate Furnace And In A Fluidized Bed Incinerator: WtE, Recycling And Environmental Concerns

The Indaver integrated grate furnace, incinerating municipal solid waste (MSW) along with comparable industrial waste, is described. In the installation, energy is recovered by producing steam which is delivered to other companies, or used to generate electricity. The bottom ashes are wet-washed; ferrous and non-ferrous metals and granulates are recovered. Next to the grate furnace, a fluidized bed combustor (FBC) operated by SLECO is situated. It can co-incinerate various types of industrial wastes (including ASR), RDF, waste water treatment (WWT) sludges, etc. and produces steam to generate electricity. The bottom ashes are recovered as secondary raw material. It is demonstrated that both installations have a good environmental performance and address many aspects of cleaner production. This way, both grate furnace and FBC may play an important role in sustainable waste management. Depending on the fractions of the energy carrier(s), the actual energy recovery varies from 41% for the grate furnace (steam + electricity) to 27% for the FBC (only electricity). The most important airborne emissions and solid residues are monitored in both installation and are discussed in detail. For all components of interest, emissions remain well below Flemish limit values. Moreover, it was shown that both installations act as a POP sink when flue gas emissions are taken into account as a POP output. From the bottom ashes of both incinerators ferrous and non-ferrous metals and granulates are recovered, representing 19.9 and 9.2 wt% of the original waste input of respectively the grate furnace and the FBC. When introducing higher amounts of heavy metals into the FBC, co-incinerating ASR, the bottom ashes still fulfil Flemish requirements for use as secondary raw material.