An experimental simulation study of conventional waste burning practices in India for the assessment and inventorisation of PCDD/F/dl-PCB emissions.

The paper reports an update to the polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) annual emission inventory of India from open burning of municipal solid wastes (MSW) through the generation of nation-specific emission factors for air (EFair) and burned residue (EFland) vectors. The MSW characteristics and modes of disposal practiced in Indian cities exhibits subtle variations from that of developed nations due to differences in food habits, living standards and climatic conditions. The annual emission calculations based on EFs from hitherto studies simulating conditions prevailing in developed countries can lead to anomalous accounting of emission levels. It is the first experimental study reported from Indian subcontinent to determine EFs of dioxins and dl-PCBs from MSW open burning by simulated combustion experiments conducted in a custom fabricated Open Burning Test Facility (OBTF) - "Burn Hut", using real dumpsite waste samples. Iso-kinetic sampling and coning and quartering methods were employed for the sampling of air and land emissions from combustion experiments. The PCDD/F's EFair ranged from 3 to 675 µg toxicity equivalence (TEQ)/ton of waste with a geometric mean (GMair) of 67.0 µgTEQ/ton and EFland ranged from 10 to 2531 µgTEQ/ton waste (GMland - 100.0 µgTEQ/ton). The EFair and EFland of dl-PCBs ranged from 0.5 to 46 µgTEQ/ton (GMair 7.0 µgTEQ/ton) and 0.5 to 96 µgTEQ/ton of waste (GMland 6.0 µgTEQ/ton) respectively. A detailed assessment of correlations between emission and MSW composition/combustion practices were conducted along with a comparative evaluation of EFpresent vis-à-vis EFs reported elsewhere.

Development of saleable chloride free iron oxide from hazardous waste in titanium industries via layered double hydroxide formation.

Mining and metal processing industries constitutes a major source of environmental pollution, albeit its huge impact on a nation's economic and industrial growth. The collaborative approach in waste management where wastes in one process/industry turns out to be a resource for another is extremely useful to sustain industries. Titanium dioxide pigment production industry operating via chloride process expels hazardous iron oxide waste byproduct rich in chloride content. The slow leaching of highly acidic and chloride rich effluents (2-5 wt.%) along with toxic heavy metals from iron oxide storage ponds in titanium industries pose serious threat to the human health and environment. The present paper describes the development of an innovative zero discharge chloride removal process via formation of layered double hydroxides (LDHs) from iron oxide waste byproduct, thereby enabling the end use applications of iron oxide. It is the first such study reported on the value addition of hazardous industrial residues via LDH formation. The developed co-precipitation process recorded maximum chloride removal efficiency in the range of 85-95%. The resultant precipitate i.e., the Friedel's salt was characterized by various techniques such as XRD, XRF and SEM-EDX and confirmed the effective removal of chlorides. The application potential of the process in real iron oxide wash waters with 95% removal efficiency and the possible reusability of precipitate utilizing the "memory effect" of LDHs were found to be highly promising. The study demonstrated the unique application potential of the process in chloride rich iron oxide wash waters unlike other industrial/domestic wastewaters, wherein other anionic species has a detrimental effect. The value added iron oxide can find application in steel industries and can mitigate the environmental and health concerns arising from the long term storage of hazardous iron oxide in mineral processing industries.

Foraging animal origin food samples as passive indicators of dioxin-like POPs contamination in industry sites: Method development, characterisation and risk assessment.

Titanium dioxide (TiO2) is an important industrial chemical, and studies suggest its major production route - the chloride process could lead to the generation of unintentional dl-POPs. However, no relevant studies assessed the occurrence of dl-POPs associated with TiO2 production in the industrial zones, which is mostly due to the ultra-trace level distribution of these compounds in environmental compartments. The present study explored the novel possibility of utilising foraging animal-origin foods as sensitive indicators for addressing this challenge and generated a globally beneficial dataset by assessing the background levels of dl-POPs in the vicinity of a TiO2 production house in Southern India. Systematic sampling of foraging cow's milk and free-ranging hen's eggs was carried out from the study site, and the dl-POPs assessments were conducted utilising an in-house developed cost-effective GC-MS/MS-based analytical methodology. The median dl-POPs levels in milk and egg samples were about 3 times higher than the control samples collected from farm-fed animals and retail markets. The contaminant loads in the foraging animal-origin food samples were further traced to their presence in environmental compartments of soil and sediment and admissible degree of correlations were observed in congener fingerprints. Elevated health risks were inferred for the population in the industrial zones with weekly intakes weighing about 0.15-17 times the European Food Safety Authority-assigned levels. The consumption of foraging cow's milk was observed to have a higher contribution towards the hazard indices and cancer risk estimates and were significantly higher (p < 0.05) for children. The study also presents a critical validation of the GC-MS/MS-based method for the purpose of regulatory monitoring of dl-POPs, which could be of practical significance in economies in transition.