Alok Sinha

Public health risk assessment with bioaccessibility considerations for soil PAHs at oil refinery vicinity areas in India

Populations living in the vicinity of oil refinery sludge deposition sites may be at greater risk of potential exposure to polycyclic aromatic hydrocarbons (PAHs) through inhalation, ingestion, and direct contact with contaminated media. Three Indian oil refinery sludge deposition sites (at Haldia, Barauni and Guwahati) were chosen for study. Soil samples were collected from three different locations at each site. Mild solvent extraction by butanol and exhaustive extraction by acetone/hexane have been conducted to estimate the bioaccessible PAHs beside the total extractable PAHs content of the soil samples. Concentrations of 13 PAHs in the soils were found to be in a range of 67.02-95.21μg/g and bioaccessible PAHs were in a range of 19.296-36.657μg/g. A probabilistic health risk assessment with bioaccessibility considerations was carried out using Monte Carlo simulations for the estimation of the cancer risk exposed to the PAHs. The 90th percentiles cancer risks with bioaccessibility considerations of soil PAHs for children is 6.506E-05 and for the adults the risk is 6.609E-05. Risk assessments on extracted PAHs from exhaustive solvent extraction can overestimate the risk by 2.87-2.89 folds at 90% confidence level with respect to the biomimetic mild extraction procedure using butanol. According to USEPA above 1×10-6 extra risk of cancer is an alarm towards management. So, public health issues due to PAHs is imminent in these oil refinery vicinity areas. Sensitivity analysis revealed exposure duration (ED) and relative skin adherence factor for soil (AF) as the most influential parameters of the assessment. The profiling and risk assessment study with bioaccessibility considerations of PAHs from soil indicates that high PAHs concentration can lead to higher cancer risk for the vicinity area residents and local government should take immediate management actions.

Profiling and Health Risk Assessment of PAHs Content in Tandoori and Tawa Bread from India

ABSTRACT The current study was carried out to assess and understand potential health risk and to examine the impact of 16 polycyclic aromatic hydrocarbons (PAHs) in Indian tandoori and tawa breads served in 8 different profile restaurants of Dhanbad city. Total PAH concentration in tandoori bread ranged between 113.36 and 211.19 µg/kg and for tawa bread between 59.64 and 77.12 µg/kg. PAHs with 4 and 5 rings found to have dominating contribution (up to 50% of total PAHs) in all the analyzed samples. The diagnostic ratio study of all the samples concluded that the PAHs in tandoori bread have pyrogenic origin, whereas in tawa bread petrogenic combustion. Cancer risk for tandoori breads ranged (5–95% probability range) from 2.33E−06 to 9.15E−05 with a mean of 3.31E−05 for children and 5.27E−06 to 1.66E−04 with a mean of 6.50E−05 for adults. Similarly, for tawa breads, the cancer risk ranges from 6.30E−07 to 2.50E−05 with a mean of 9.07E−06 for children and from 1.44E−06 to 4.45E−05 with a mean of 1.77E−05 for adults. Exposure duration and cancer slope factor are the most influential parameters of the simulation. Carcinogenic potency in tandoori bread was almost 3.7 times than that of tawa bread.

Cancer Risk Assessment of Polycyclic Aromatic Hydrocarbons in the Soils and Sediments of India: A Meta-Analysis

A carcinogenic risk assessment of polycyclic aromatic hydrocarbons in soils and sediments was conducted using the probabilistic approach from a national perspective. Published monitoring data of polycyclic aromatic hydrocarbons present in soils and sediments at different study points across India were collected and converted to their corresponding BaP equivalent concentrations. These BaP equivalent concentrations were used to evaluate comprehensive cancer risk for two different age groups. Monte Carlo simulation and sensitivity analysis were applied to quantify uncertainties of risk estimation. The analysis denotes 90% cancer risk value of 1.770E−5 for children and 3.156E−5 for adults at heavily polluted site soils. Overall carcinogenic risks of polycyclic aromatic hydrocarbons in soils of India were mostly in acceptance limits. However, the food ingestion exposure route for sediments leads them to a highly risked zone. The 90% risk values from sediments are 7.863E−05 for children and 3.999E−04 for adults. Sensitivity analysis reveals exposure duration and relative skin adherence factor for soil as the most influential parameter of the assessment, followed by BaP equivalent concentration of polycyclic aromatic hydrocarbons. For sediments, biota to sediment accumulation factor of fish in terms of BaP is most sensitive on the total outcome, followed by BaP equivalent and exposure duration. Individual exposure route analysis showed dermal contact for soils and food ingestion for sediments as the main exposure pathway. Some specific locations such as surrounding areas of Bhavnagar, Raniganj, Sunderban, Raipur, and Delhi demand potential strategies of carcinogenic risk management and reduction. The current study is probably the first attempt to provide information on the carcinogenic risk of polycyclic aromatic hydrocarbons in soil and sediments across India.

Health risk assessment and source study of PAHs from roadside soil dust of a heavy mining area in India

ABSTRACT The total concentrations of 13 detected polycyclic aromatic hydrocarbons (PAHs) in different traffic soil samples of Dhanbad heavy mining area, India, were between 8.256 and 12.562 µg/g and were dominated by four ring PAHs (44%). Diagnostic ratio study revealed that fossil fuel burning and vehicular pollution are the most prominent sources of the PAHs in roadside soil even at a heavy coal mining area. The 90th percentiles cancer risks determined by probabilistic health risk assessment (Monte Carlo simulations) for both the age groups (children and adults) were above tolerable limit (>1.00E-06) according to USEPA. The simulated mean cancer risk was 1.854E-05 for children and 1.823E-05 for adults. For different exposure pathways, dermal contact was observed to be the major pathway with an exposure load of 74% for children and 85% for adults. Sensitivity analysis demonstrated relative skin adherence factor for soil (AF) is the most influential parameter of the simulation, followed by exposure duration (ED).

A Review on Membrane Fouling in Membrane Bioreactors: Control and Mitigation

The growing interest toward the effective treatment of wastewater of different origin has increased worldwide, where membrane bioreactor (MBR) technology appears as the most appropriate treatment system. Membrane provides solid–liquid separation in MBRs and releases high-quality effluents which could be further reused for different purposes. The conventional biological treatment system often faces challenge of sludge disposal and requires larger footprint for their operation. These issues can be combated using MBR systems. However, MBR system associates with the membrane fouling problems, which limits its widespread application in wastewater treatment systems. Membrane fouling requires repeated cleaning that may reduce the membrane life span and frequent membrane replacement which incurs high cost. Membrane fouling leads to increase in transmembrane pressure (TMP), rapid declination of permeate flux, and increase in filtration resistance. The main factors that influence the membrane fouling are membrane characteristics, biomass characteristics, operating conditions, and membrane configuration. To address the recent advances made in MBR fouling, this paper reviews the mechanism, influencing factors, and methods for controlling and preventing membrane fouling. In addition, this chapter also deliberates the use of various adsorbents for controlling membrane fouling in MBRs.

Assessment of hazard on human health and aquatic life in acid mine drainage treated with novel technique

ABSTRACT The research investigates a novel method to treat acid mine drainage (AMD) using lime and sodium hydroxide modified fly ash (NCFA) with varied dose and time. The analysis showed that pH was raised to 8.24 and approximately 99% of Al, Cd, Cr, Cu, Ni, Pb; 97% of Co, Mn, Zn; 83% of Fe; 35% of Mg; 21% of Na, SO4; and 49% of Cl were removed after 20 min of reaction with 70 gm L−1 dose. The precipitation of these metals as well as sulfate in the form of gypsum on the NCFA surface was detected by X-ray diffraction and field emission scanning electron microscope. The possible mineral phases were identified by PHREEQC geochemical modeling. However, this analysis does not evaluate the hazard of the treated water to aquatic life and human health. Therefore, water quality index (WQI) and hazard index (HI) is proposed in this study to evaluate the risk and identify the optimum dose and time for AMD treatment. These indices confirmed that AMD should be treated with 70 gm L−1 dose of NCFA for 20 min to safeguard human and aquatic life. This study gives a new direction to treat AMD effectively and identify its potential risk to living organisms.

Performance evaluation and substrate removal kinetics in an up-flow anaerobic hybrid membrane bioreactor treating simulated high-strength wastewater

ABSTRACT The prime objective of the present study is to evaluate the performance of novel up-flow anaerobic hybrid membrane bioreactor (An-HMBR) treating high-strength wastewater (synthetic) using polyurethane foam as filter media. Treatment efficiency of the entire An-HMBR varied from 88–97% corresponding to 0.67–3.90 d of hydraulic retention time (HRT) with organic loading rate of 6.4–1.06 kg COD m−3 d−1. The modified Stover–Kincannon model was the most appropriate model for An-HMBR and anaerobic hybrid bioreactor (excluding membrane). The suspended growth system in An-HMBR could be described by both modified Stover–Kincannon and Grau second order model. The attached growth system in An-HMBR followed conventional Monod’s kinetics. A novel combination of suspended, attached and membrane in single reactor increased the solid retention time to as high as 756 d at 3.9 d HRT which not only improved the COD removal efficiency but also enhanced the performance of the membrane. GRAPHICAL ABSTRACT

Assessment of Serratia sp. isolated from Iron Ore mine in Hexavalent Chromium reduction: Kinetics, Fate and Variation in Cellular Morphology

ABSTRACT Serratia sp. strain SU.ISM.1 was isolated from Noamundi iron ore mines for the first time and was observed for hexavalent chromium reduction, and growth kinetics modelling was applied for bacterial chromium reduction. For 4–8 ppm of hexavalent chromium concentration, complete reduction was observed within 36 h when the selected isolate was applied, and for 12–20 ppm chromium concentration, complete reduction was achieved within 48 h. The viable biomass concentration increased up to 36 h of treatment time, after which the biomass concentration gradually declined. The Aiba model of product inhibition growth kinetics best described the growth of biomass in the presence of hexavalent chromium. The total mass conversion of Cr(VI) to Cr(III) for 4, 8, 12, 16 and 20 ppm was found to be 94.9%, 88.5%, 74.66%, 70.75% and 78.8%, respectively. The AFM and FESEM studies showed that the roughness of the cell surface increased with increasing concentration of hexavalent chromium, probably due to adsorption of chromium. GRAPHICAL ABSTRACT

Modification, characterization and investigations of key factors controlling the transport of modified nano zero-valent iron (nZVI) in porous media

ABSTRACT Enhancement of nano zero-valent iron (nZVI) stability and transport in the subsurface environment is important for in situ degradation of contaminants. Various biodegradable dispersants (poly (acrylic acid) (PAA), Tween 20 and Reetha Extracts) have been tested to evaluate their effectiveness in this regard. Application of dispersants during the synthesis of nZVI have positively affected the reduction in particle size. The transport capacity in terms of fraction elution at different pore water velocities and collector grain size (filter media) was analyzed using correlation equation for the filtration model by Rajagopalan and Tien (RT model). At a surfactant concentration of 5% for PAA, Tween 20 and Reetha (Sapindus trifoliata) extracts, the lowest particle size and the highest zeta potential achieved are 8.67 nm and −55.29 mV, 75.24 nm and −62.68 mV, 61.6 nm and −37.82 mV, respectively. The trend of colloidal stability by The Derjaguin—Landau—Verwey—Overbeek (DLVO) Theory model for PAA and Reetha applied concentration was 3% > 4% > 5% > 2% > 1% > 0%. For Tween 20, modified nZVI particle shows a higher repulsive force with increasing Tween 20 concentration. Results indicated that some mechanisms such as aggregation, ripening and surface modification with different carrier pore water velocities had a considerable impact on nZVI retention in porous media. The results indicate that natural surfactant like Reetha extracts exhibits an alternative potential capacity for nZVI modification in comparison with synthetic surfactants (PAA and Tween 20). GRAPHICAL ABSTRACT