An Innovative Approach to Assess the Ecotoxicological Risks of Soil Exposed to Solid Waste

The adoption of sustainable waste management strategies is a challenge faced by most European countries, mainly due to the need to generate less waste and replace landfills with new methods of waste treatment, associated with increases in the separate collection of waste and recycling rates. This paper highlights the significance of environmental legislation regarding waste removal to protect ecosystems. The aim was to predict ecological responses to heavy metals in soil exposed to hazardous waste and to identify environmental hazards in landfills, small illegal waste dumps, and litter, in addition to identifying if heavy metal accumulation in the investigated soil samples showed a single or cumulative risk. This is an innovative method to predict the ecological risk generated by hazardous waste landfills. The assessment of ecological risks was based on the evaluation of a heavy metal soil contamination factor, pollution index of soil loadings, a geo-accumulation index for heavy metals, and potential ecological risk. The current study is also the first to attempt to identify the dimension of risk based on the type of waste deposit (landfill, small illegal waste dump, and litter) and to identify potential patterns. The geological index corresponding to cadmium Igeo(Cd) showed heavy contamination in the soil samples from the landfill and moderate contamination for those from the illegal waste dumps. These findings indicate that soil contamination is influenced by contamination time, anthropogenic processes, and a history of industrial activity, and not only by waste composition and storage. The present study shows that cadmium might be considered a latent fingerprint for waste disposal, which is correlated to the industrialization level and rehabilitation procedures.

VALORIZAÇÃO DOS PRODUTOS ORIUNDOS DO RESÍDUO DE COURO WET-BLUE HIDROLISADO

RESUMOO processo de transformação de pele em couro gera um expressivo volume de efluente, emissões atmosféricas e de resíduos sólidos. Dependendo dos insumos e principalmente do curtente utilizado, o curtimento pode gerar resísuos perigosos. É o caso dos processos que utilizam o óxido cromo como curtente. Estima-se que 90% dos curtumes utiliza o óxido de cromo em função do seu custo benefício. Visando reduzir o envio de resíduo de couro wet-blue para aterros de resíduos perigosos, este trabalho tem como objetivo propor um método que permite reduzir a concentração de cromo do resíduo. O estudo compreendeu as seguintes etapas: 1) caracterização físico-química do resíduo wet-blue; 2) testes de hidrólise em fulões piloto com emprego de ácido cítrico, variando relação cromo:ácido, pH e método de lavagem; 3) caracterização físico química do colágeno hidrolisado e do banho residual do processo de hidrólise. Os resultados obtidos revelaram que a hidrólise com ácido cítrico possibilitou uma redução de até 87,35% do cromo presente no resíduo de wet-blue e resultou na geração de dois produtos: um material sólido colagênico rico em nitrogênio e com potencial de ser utilizado como fonte de nutrientes para plantas, como matéria prima para produção de adesivo ou adsorvente, e um efluente de coloração escura com pH baixo e com aproximadamente 500 mg.Cr.L-1 com possibilidade de ser reaproveitado no processo de curtimento. Assim, o estudo demonstrou uma alternativa tecnológica para o tratamento de resíduos de wet-blue, possibilitando o reaproveitamento de materiais que seriam descartados em aterros de resíduos perigosos.Palavras-chave: Descromagem. Hidrólise Ácida. Resíduo de Couro. ABSTRACTThe process of transforming skin into leather generates a significant volume of effluent, atmospheric emissions and solid waste. Depending on the inputs and mainly the tanner used, tanning can generate dangerous residues. This is the case of processes that use chromium oxide as a tanner. It is estimated that 90% of tanneries use chromium oxide due to its cost benefit. Aiming to reduce the shipment of wet-blue leather waste to hazardous waste landfills, this work aims to propose a method that allows reducing the chromium concentration of the waste. The study comprised the following steps: 1) physical chemical characterization of wet-blue waste; 2) hydrolysis tests on pilot drums using citric acid, varying the chromium: acid ratio, pH and washing method; 3) physical and chemical characterization of the hydrolyzed collagen and the residual bath of the hydrolysis process. The results obtained revealed that the hydrolysis with citric acid allowed a reduction of up to 87.35% of the chromium present in the wet-blue residue and resulted in the generation of two products: a solid collagen material rich in nitrogen and with the potential to be used as source of nutrients for plants, as raw material for the production of adhesive or adsorbent and a dark colored effluent with low pH and approximately 500 mg.Cr.L-1 with the possibility of being reused in the tanning process. Thus, the study demonstrated a technological alternative for the treatment of wet-blue waste, enabling the reuse of materials that would be disposed of in hazardous waste landfills.Keywords: Acid Hydrolysis. Decromatization. Leather residue.

Hazardous Waste Disposal in Stromatolitic-Limestone Terrain and Hexavalent Chromium Contamination in Chhattisgarh State, India

Background. Hexavalent chromium-containing waste from chromite ore processing is a major environmental health hazard due to its high toxicity. There have been instances of improper and unsafe disposal of this waste, leading to environmental health hazards. Objectives. The objective of the present study was to identify the cause of yellow colored water discharge and reported health issues in nearby residents and cattle. In addition, it investigated the improper disposal of chromite ore processing residue (COPR), a hazardous waste, in an abandoned quarry in stromatolitic-limestone terrain in central-east India. Methods. Standard methods of analysis of water and wastewater were used for the analyses of variables, including hexavalent chromium (Cr(VI)), pH, sulfate (SO42−), chlorine (Cl−), total hardness, calcium (Ca(II)), magnesium (Mg(II)), alkalinity and sodium (Na(I)) with proper sampling, quality assurance, and quality control protocols. Onsite Cr(VI) was analyzed using a chromium testing kit, and in the laboratory by atomic absorption spectrophotometry. Results. Large-scale contamination of surface and groundwater was noted due to the migration of hexavalent chromium-contaminated yellow colored leachate. High levels of hexavalent chromium were noted in the samples. The maximum Cr(VI) concentration observed was 1050 mg/L in leachate, 22 mg/L in surface water and 0.26 mg/L in the groundwater sample. Acute health effects were noted in cattle and by residents who consumed the highly contaminated water. Conclusions. A large volume of discharge of hexavalent chromium contamination from the COPR landfill was found, indicating the absence of containment features in the design (double high-density polyethylene liners, clay, leachate collection). Disposal of COPR in an abandoned limestone mine is inadvisable. The highly fractured stromatolitic-limestone environment at the study site was found to offer almost no resistance to the mobilization of Cr(VI) due to the absence of organic or eukaryotic deposition in the stromatolitic environment. It was also noted that the drainage pattern of the area facilitates a possible translocation of contaminated discharge to the nearby river system. Nearby residents were unaware of the adverse impacts of the contaminated leachates and were using the contaminated water for bathing, washing, etc. Applicable Indian governmental regulations regarding the construction of hazardous waste landfills were found to be insufficient with respect to the use of inactive limestone mines as landfill sites. Competing Interests. The authors declare no competing financial interests.

Halocarbon Emissions from Hazardous Waste Landfills: Analysis of Sources and Risks

Landfills are sources of fugitive volatile organic carbon (VOC) emissions, including halocarbons. The objective of this study was to evaluate the contribution of halogenated VOCs to the health risks associated with the exposure of workers operating in landfills, gathering information on the role of endogenous/exogenous sources present in anthropized areas. A hazardous waste landfill located in Turin, Italy was used as a case study. Ambient concentrations of 10 pollutants (BTEX, styrene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1,2-dichloroethane, and 1,2-dichloropropane), measured in 10 points of the landfill area, were considered and analyzed. The data had a monthly frequency and covered two years. A cumulative health risk analysis was conducted by applying a Monte-Carlo method. The results showed that the contribution of 1,2-dichloroethane and 1,2-dichloropropane was 17.9% and 19.4% for the total risk and hazard index respectively. Benzene and ethylbenzene gave the highest contribution to the total risk (56.8% and 24.8%, respectively). In the second phase of the study, waste typologies that are possibly responsible for halocarbon emissions were investigated. Halocarbon concentration trends and waste disposal records were compared. Although further investigation is needed, some waste typologies were not excluded to contribute to halocarbon emissions, in particular sludge coming from wastewater treatment plants.

Hydraulic Conductivity of Compacted Lime-Softening Sludge Used as Landfill Liners

The research goal was to investigate the hydraulic conductivity of compacted lime-softening sludge as a material to be applied to landfill liners. In doing so, the effect of compaction and moulding moisture content on the sludge hydraulic conductivity was assessed. An approximate polynomial k10mean at hydraulic gradients ≥30 for degree of compaction (0.95–1.05) and moulding moisture content (28%–36%) was determined. The results of short-term tap water permeation tests revealed that all hydraulic conductivity values were less than 2.5•10–8 m/s. A lowest hydraulic conductivity of 6.5•10–9 m/s, as well as a corresponding moisture content of 31% were then established. The long-term hydraulic conductivity was measured with tap water, distilled water, NaOH and HCl solutions and municipal waste leachate. The factors of permeating liquids and permeation time significantly affected the initial hydraulic conductivity. The long-term hydraulic conductivity increased for NaOH and HCl solutions and decreased for tap and distilled water. A significant reduction of hydraulic conductivity was observed for leachate permeation. The investigated material met the requirements for the liner systems of inert landfill sites regardless of pH and the limit value for hazardous and non-hazardous waste landfills.

Identification of management strategies and generation factors for spent lead acid battery recovery plant wastes in Turkey

The recovery of spent or waste lead acid batteries is important both for the management of lead input to the environment and to meet the lead demand of the market in a more energy and cost effective manner than primary production. As an important producer of lead acid batteries for the Middle Eastern and Eastern European market, Turkey seems to meet 22%–52% of its total lead demand by waste lead acid battery recovery. In this study, the wastes from Turkish waste lead acid battery recovery plants are identified and management strategies that are both technically sufficient and economically feasible for each of these wastes are complied. Furthermore, ranges of the amount of each waste generated per mass of final lead produced in these plants are estimated. Some of the most significantly generated wastes are lead containing dusts, wash water treatment sludges and slags from smelting furnaces with generation rates between 5–250, 1–150 and 5–100 kg t−1 of product lead, respectively. Many of these can be fed back to the recovery process inside the plants except a subset of slags that are called ‘final slag’ and have low (5%–6%) lead content. Final slags can either be recovered for the production of cement, road-filling materials or abrasives proven that they are in a non-leachable, stable state or should be stored at hazardous waste landfills. For improved environmental performance, newly emerging techniques that eliminate the generation of such slags are also discussed and suggested.

icsid’s Neoliberal Approach to Environmental Regulation in Developing Countries

With the intensification of their participation in the foreign investment regime, Latin American States are finding it difficult to implement measures beneficial to protecting their environments due to their obligations to third States. This governance deficit is further compounded by the regime’s neoliberal predisposition in favour of property protection, which has penetrated the system and implicated the system of investment treaty arbitration, the regime’s primary dispute settlement mechanism. The International Centre for Settlement of Investment Disputes (icsid) has also been implicated. This is seen in the momentous diversity in investor-State disputes resolved by various icsid tribunals, which concern attempts by Latin American States to protect their physical environments such as the protection of wildlife or other matters such as the regulation of hazardous waste landfills and ensuring that citizens have access to clean water. Tribunals have approached such disputes primarily from a commercial standpoint, ignoring non-market alternatives such as environmental considerations.

Characterizing the ageing of a geosynthetic clay liner through electrical resistivity

In closed hazardous waste landfills, impermeable layered covers mainly composed of clays, geosynthetic clay liner (GCL) or geomembrane, etc. are used to seal in the waste to minimize water infiltration and accumulation of leachate inside the waste. An experimental site of landfill cap was realized with sodium-activated calcium bentonite GCL at a depth of 0.45 m covered by gravels and top soil. The monitoring of this site was performed during 32 months with measurements of weather conditions, and electrical resistivity tomography (ERT) and geotechnical measurements at the end of the monitoring. The two different methods underlined that the GCL’s electrical resistivity decreased after 22 months subsequent to its installation; moreover, it was possible to detect the defects that had been made in the GCL prior to closure, to simulate factors affecting GCL performance. Thereby the analyses made on the GCL samples taken at two locations in the vicinity of the ERT profile highlighted changes in the intrinsic properties of the material. Changes in the proportion of sodium and calcium cations occurred and its hydraulic conductivity increased from 5 × 10−11 to 3 × 10−6 m/s. Thus, this study shows that electrical resistivity is suitable to characterize the ageing of a GCL.