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.

Dioxins emissions from bio-medical waste incineration: A systematic review on emission factors, inventories, trends and health risk studies

COVID-19 has aggravated the biomedical waste generation all over the world and the concern for its safe disposal is on the rise. The vast majority of healthcare systems employ incineration as their treatment method considering its agility to reduce the waste volume by up to 95-96% and high-temperature inactivation of infectious biological materials. However, incinerator emission is a significant contributor of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) according to various national inventories across the globe. Bio-Medical Waste Incinerators (BMWIs) are the dominant form of incinerator plants in developing nations and hence BMWI emissions were found to contribute lion's share of national dioxins inventories in most of these countries. The Stockholm Convention on POPs played a key role in imbibing significant urge on the dl-POPs monitoring studies of incinerators internationally and on controlling the average incinerator emission levels. Though many national/international agencies endorse a stringent incinerator stack emission standard of 0.1 ngTEQ/Nm3, there are some differences observed in nation-to-nation regulatory scenarios. This paper reviews and reports on the dioxins emission and health risk studies associated with bio-medical waste incineration over the last three decades (1990-2020) with a comprehensive spatial and temporal emission trend analysis. An overview of important national and international regulations, national inventories and emission factors for the biomedical waste incineration sector is also reviewed in detail. The study observes that continuous regulatory monitoring and logical relaxations can enhance the performance of the existing facilities ensuring low emissions and minimal risk.

Integrated Fenton-like and ozonation based advanced oxidation processes for treatment of real-time textile effluent containing azo reactive dyes

The treatment of real-time textile effluent, collected from the Common Effluent Treatment Plant (CETP) of Kerala Industrial Infrastructure Development Corporation (KINFRA) at Kannur (District), Kerala (State), India, have been studied by utilizing the Fenton-like and ozone (O3) based advanced oxidation processes (AOPs). The Fenton-like AOP has been conducted as the pre-treatment of textile effluent involving the activation of persulfate (PS) and hydrogen peroxide (H2O2) as a single and the mixed oxidants by using the Flyash (FA)-Pd composite particles as the activator. The maximum chemical oxygen demand (COD) removal of 84% has been observed for a stand-alone O3 based treatment at an O3 flow rate of 5-6 g h-1. By conducting the pre-treatment of textile effluent with the PS, H2O2, and mixed oxidants (PS and H2O2) based Fenton-like AOPs, the COD removal after an O3 based post-treatment has been observed to be 83, 87, and 93% respectively at an O3 flow rate of 2, 3, and 5 g h-1. Hence, the Fenton-like pre-treatment involving the activation of mixed oxidants has been determined to be the best method for the highest COD removal of real-time textile effluent. The optimum values of initial oxidant-ratio (initial [H2O2]:initial [PS]), initial oxidant-dosage, and ozonation time, for the mixed oxidants based Fenton-like pre-treatment, have been determined to be 3 wt% mM-1, 6:2 wt% mM-1, and 60 min respectively. Under the most optimum conditions, the COD removal has been attributed to the combination of O2•- (for the pre-treatment) and •OOH (for the post-treatment) which possess relatively lower oxidation potential values.

Abandonment of fibreglass reinforced plastic fishing boats in Kerala, India, and chemical emissions arising from their burning

Little information exists on the fate and impacts of boats constructed of fibreglass reinforced plastic (FRP) once they reach their end-of-life. In this study, the number of abandoned fishing boats constructed of FRP or constructed of plywood-wood and sheathed by FRP has been determined along the coast of Kerala, India, and chemical emissions have been estimated when boats are burned as a means of disposal. A total of 292 abandoned boats were observed across eight coastal transects constructed around selected landing centres, with abandonment ranging from 13 to 48 per km (average = 29 km-1). This results in the generation of 1420 kg of FRP debris (glass mat and epoxy resin) per km of coastline. A controlled combustion experiment, simulating open burning, revealed that 63% of original boat mass is emitted to the atmosphere, with the remainder forming a burnt residue. Total concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans emitted and remaining were found to be 2.6 ng Nm-3 and 249.6 μg kg-1, respectively, with respective calculated toxicity equivalence (TEQ) levels of 437.6 pg TEQ Nm-3 in air emissions and 26.6 μg TEQ kg-1 in the residue. These figures are equivalent to the total emission from FRP boat burning of about 17,000 μg TEQ t-1. Burning also generates significant quantities of potentially toxic metals, with resulting concentrations of Co, Cr and Cu close to or exceeding soil guideline values. The study calls for a greater awareness of the impacts arising from boat abandonment and burning amongst fishermen, and guidelines or regulatory protocols regarding safe and sustainable boat disposal or recycling.

Dioxin-like POPs emission trends as a decision support tool for developing sustainable MSW management scheme -an exploratory study

The paper reports on an innovative application of dioxin-like persistent organic pollutants (dl-POPs) emission trends as a measure of environmental performance for designing feasible municipal solid waste management (MSWM) schemes. MSWM systems are highly dependent on the income status and the population density and it is quintessential for developing countries to devise strategies suiting to its characteristics rather than simply adapting successful processes/technologies in developed nations. Hence a lower-middle-income, high-density populated state of India - Kerala, which represents the typical scenario of majority of towns in developing countries was selected as the verification study site. Annual inventorisation of dl-POPs for the current scenario of the state was developed as a spatial model at the lowest administrative block level using geographical information system for the easy and effective comparative assessment. Further, a dl-POPs emission based MSWM scheme which could reduce up to 65% of emissions from current scenario has been developed and compared it with contemporary life cycle assessment (LCA) and life cycle cost analysis (LCCA) schemes in terms of green-house gas emissions (GHG) and landfill area requirements as environmental performance validation. Daily exposure dose of dl-POPs were predicted from the per-capita annual emission associated with different MSWM schemes and hazard quotients were also calculated to provide an overview of the health risk posed by the emissions. The predicted health risk factors were observed to be 5 times higher than the threshold level in current scenario whereas 10 times reduction in dose levels could be achieved through the proposed scheme of MSWM.

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 (EF_air) and burned residue (EF_land) 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 EF_air ranged from 3 to 675 μg toxicity equivalence (TEQ)/ton of waste with a geometric mean (GM_air) of 67.0 μgTEQ/ton and EF_land ranged from 10 to 2531 μgTEQ/ton waste (GM_land - 100.0 μgTEQ/ton). The EF_air and EF_land of dl-PCBs ranged from 0.5 to 46 μgTEQ/ton (GM_air 7.0 μgTEQ/ton) and 0.5 to 96 μgTEQ/ton of waste (GM_land 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 EF_present 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.