PFAs (poly and perfluoroalkyl compounds) are hazardous and bioaccumulative chemicals that do not ... more PFAs (poly and perfluoroalkyl compounds) are hazardous and bioaccumulative chemicals that do not readily biodegrade or neutralize under normal environmental conditions. They have various industrial, commercial, domestic and defence applications. According to the Organization for Economic Co-operation and Development, there are around 4700 PFAs registered to date. They are present in every stream of life, and they are often emerging and are even difficult to be detected by the standard chemical methods. This review aims to focus on the sources of various PFAs and the toxicities they impose on the environment and especially on humankind. Drinking water, food packaging, industrial areas and commercial household products are the primary PFAs sources. Some of the well-known treatment methods for remediation of PFAs presented in the literature are activated carbon, filtration, reverse osmosis, nano filtration, oxidation processes etc. The crucial stage of handling the PFAs occurs in determining and analysing the type of PFA and its remedy. This paper provides a state-of-the-art review of determination & tools, and techniques for remediation of PFAs in the environment. Improving new treatment methodologies that are economical and sustainable are essential for excluding the PFAs from the environment.
Volatile fatty acids (VFAs) are the building blocks of the chemical industry, and they are the pr... more Volatile fatty acids (VFAs) are the building blocks of the chemical industry, and they are the primary contributors to the planet's organic carbon cycle. VFA production from fossil fuels (mostly petroleum) is unsustainable, pollutes the environment, and generates greenhouse gases. As a result of these issues, there is a pressing need to develop alternate sources for the long-term generation of VFAs via anaerobic digestion. The accessible feedstocks for its sustainable production, as well as the influencing parameters, are discussed in this review. The use of VFAs as a raw material to make a variety of consumer products is reviewed in order to find a solution. It also bridges the gap between traditional and advanced VFA production and utilization methods from a variety of solid and liquid waste sources for economical stability.
Occurrence and concentrations of 26 per-and polyfluoroalkyl substances (PFASs) were evaluated in ... more Occurrence and concentrations of 26 per-and polyfluoroalkyl substances (PFASs) were evaluated in wastewater, surface water, soil and crop plants (yam (Dioscorea spp.), maize (Zea mays) and sugarcane (Saccharum officinarum)) in Nakivubo wetland and Lake Victoria at Kampala, Uganda. ∑PFAS concentrations in effluent from Bugolobi wastewater treatment plant (WWTP) were higher (5.6-9.1 ng L −1) than in the corresponding influent (3.4-5.1 ng L −1), indicating poor removal of PFASs within the WWTP. ∑PFAS concentrations decreased by a factor of approximately five between Nakivubo channel (8.5-12 ng L −1) and Lake Victoria (1.0-2.5 ng L −1), due to dilution, sorption to sediment and uptake by plants in the wetland. ∑PFAS concentrations were within the range 1700-7900 pg g −1 dry weight (dw) in soil and 160 pg g −1 dw (maize cobs) to 380 pg g −1 dw (sugarcane stems) in plants. The dominant PFASs were perfluorohexanesulfonate (PFHxS) in wastewater, perfluorooctanoate (PFOA) in surface water, perfluorooctanesulfonate (PFOS) in soil and perfluoroheptanoate (PFHpA) and PFOA in different plant tissues, reflecting PFAS-specific partitioning behaviour in different matrices. Soil-water partitioning coefficient (log K d) in wetland soil under yam was lowest for short-chain PFHxA (1.9-2.3 L kg −1) and increased with increasing chain length to 2.8-3.1 L kg −1 for perfluoroundecanoate (PFUnDA) and 2.8-3.1 L kg −1 for perfluoroctanesulfonate (PFOS). The log K oc values ranged between 2.2 and 3.6 L kg −1 , with the highest log K oc estimated for long-chain perfluorocarbon PFASs (i.e. PFUnDA 3.2-3.5 L kg −1 and PFOS 3.2-3.6 L kg −1). The concentration ratio (CR) between plants and soil was b1 for all PFASs and plant species, with the highest CR estimated for PFHpA (0.65-0.67) in sugarcane stem and PFBS (0.53-0.59) in yam root.
Abstract Pharmaceuticals are biologically active compounds which are used to impart therapeutic e... more Abstract Pharmaceuticals are biologically active compounds which are used to impart therapeutic effects in humans and animals. These pharmaceuticals compounds are contaminants of emerging concern due to their heavy use and release into the environment. Their persistence in waterways and drinking water has gained attention across the globe and among lawmakers, regulators, and the public, because they are active and often escape from the wastewater treatment plants (WWTPs) undisturbed or in transformed states. Most of the biological treatment technologies are not specifically designed to remove the pharmaceuticals. Moreover, the biological systems require careful selection of microbial consortium to efficiently eradicate or reduce the concentration of pharmaceuticals without having their adverse effects on the microorganisms. Therefore, in this chapter, the commonly used conventional (activated sludge process) and available technologies to eradicate pharmaceuticals from wastewater (WW) were discussed. Further novel method and advance treatment options to remove pharmaceuticals from the effluents were discussed in details. The removal mechanisms of pharmaceuticals, mainly sorption or biodegradation process and the impact parameters were elaborated. Moreover, the insights of the engineering aspects to improve the treatment efficiency of the pharmaceuticals were presented. For the stake holder, the insights of the technical and economic evaluation of the biological process were provided. In addition to pharmaceuticals WW generated from industries, the small flows generated from the healthcare centers (i.e., from pathology laboratories, private dental establishment, etc.), and their effect on the environment and the necessary measure were deliberated. Moreover, the consequences of climate change on the WWTPs and pathogen survival were well explained. Finally, the challenges to be addressed in mere future were detailed.
Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without p... more Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without pre-treatment, were assessed using mass-energy balance and the corresponding greenhouse gas (GHG) emissions. For a digestion period of 30 days, volatile solids degradation of the control sludge and the ultrasonicated secondary sludge was 51.4% and 60.1%, respectively. Mass balance revealed that the quantity of digestate required for dewatering, transport and land application was the lowest (20.2 × 10(6) g dry sludge/day) for ultrasonicated secondary sludge at 31.4 g TS/L. Furthermore, for ultrasonicated secondary sludge at 31.4 g TS/L, the maximum net energy (energy output - energy input) of total dry solids (TDS) was 7.89 × 10(-6) kWh/g and the energy ratio (output/input) was 1.0. GHG emissions were also reduced with an increase in the sludge solids concentration (i.e., 40.0 g TS/L < 30.0 g TS/L < 20.0 g TS/L). Ultrasonication pre-treatment proved to be efficient and beneficial for enhancing anaerobic digestion efficiency of the secondary sludge when compared to the primary and mixed sludge.
PFAs (poly and perfluoroalkyl compounds) are hazardous and bioaccumulative chemicals that do not ... more PFAs (poly and perfluoroalkyl compounds) are hazardous and bioaccumulative chemicals that do not readily biodegrade or neutralize under normal environmental conditions. They have various industrial, commercial, domestic and defence applications. According to the Organization for Economic Co-operation and Development, there are around 4700 PFAs registered to date. They are present in every stream of life, and they are often emerging and are even difficult to be detected by the standard chemical methods. This review aims to focus on the sources of various PFAs and the toxicities they impose on the environment and especially on humankind. Drinking water, food packaging, industrial areas and commercial household products are the primary PFAs sources. Some of the well-known treatment methods for remediation of PFAs presented in the literature are activated carbon, filtration, reverse osmosis, nano filtration, oxidation processes etc. The crucial stage of handling the PFAs occurs in determining and analysing the type of PFA and its remedy. This paper provides a state-of-the-art review of determination & tools, and techniques for remediation of PFAs in the environment. Improving new treatment methodologies that are economical and sustainable are essential for excluding the PFAs from the environment.
Volatile fatty acids (VFAs) are the building blocks of the chemical industry, and they are the pr... more Volatile fatty acids (VFAs) are the building blocks of the chemical industry, and they are the primary contributors to the planet's organic carbon cycle. VFA production from fossil fuels (mostly petroleum) is unsustainable, pollutes the environment, and generates greenhouse gases. As a result of these issues, there is a pressing need to develop alternate sources for the long-term generation of VFAs via anaerobic digestion. The accessible feedstocks for its sustainable production, as well as the influencing parameters, are discussed in this review. The use of VFAs as a raw material to make a variety of consumer products is reviewed in order to find a solution. It also bridges the gap between traditional and advanced VFA production and utilization methods from a variety of solid and liquid waste sources for economical stability.
Occurrence and concentrations of 26 per-and polyfluoroalkyl substances (PFASs) were evaluated in ... more Occurrence and concentrations of 26 per-and polyfluoroalkyl substances (PFASs) were evaluated in wastewater, surface water, soil and crop plants (yam (Dioscorea spp.), maize (Zea mays) and sugarcane (Saccharum officinarum)) in Nakivubo wetland and Lake Victoria at Kampala, Uganda. ∑PFAS concentrations in effluent from Bugolobi wastewater treatment plant (WWTP) were higher (5.6-9.1 ng L −1) than in the corresponding influent (3.4-5.1 ng L −1), indicating poor removal of PFASs within the WWTP. ∑PFAS concentrations decreased by a factor of approximately five between Nakivubo channel (8.5-12 ng L −1) and Lake Victoria (1.0-2.5 ng L −1), due to dilution, sorption to sediment and uptake by plants in the wetland. ∑PFAS concentrations were within the range 1700-7900 pg g −1 dry weight (dw) in soil and 160 pg g −1 dw (maize cobs) to 380 pg g −1 dw (sugarcane stems) in plants. The dominant PFASs were perfluorohexanesulfonate (PFHxS) in wastewater, perfluorooctanoate (PFOA) in surface water, perfluorooctanesulfonate (PFOS) in soil and perfluoroheptanoate (PFHpA) and PFOA in different plant tissues, reflecting PFAS-specific partitioning behaviour in different matrices. Soil-water partitioning coefficient (log K d) in wetland soil under yam was lowest for short-chain PFHxA (1.9-2.3 L kg −1) and increased with increasing chain length to 2.8-3.1 L kg −1 for perfluoroundecanoate (PFUnDA) and 2.8-3.1 L kg −1 for perfluoroctanesulfonate (PFOS). The log K oc values ranged between 2.2 and 3.6 L kg −1 , with the highest log K oc estimated for long-chain perfluorocarbon PFASs (i.e. PFUnDA 3.2-3.5 L kg −1 and PFOS 3.2-3.6 L kg −1). The concentration ratio (CR) between plants and soil was b1 for all PFASs and plant species, with the highest CR estimated for PFHpA (0.65-0.67) in sugarcane stem and PFBS (0.53-0.59) in yam root.
Abstract Pharmaceuticals are biologically active compounds which are used to impart therapeutic e... more Abstract Pharmaceuticals are biologically active compounds which are used to impart therapeutic effects in humans and animals. These pharmaceuticals compounds are contaminants of emerging concern due to their heavy use and release into the environment. Their persistence in waterways and drinking water has gained attention across the globe and among lawmakers, regulators, and the public, because they are active and often escape from the wastewater treatment plants (WWTPs) undisturbed or in transformed states. Most of the biological treatment technologies are not specifically designed to remove the pharmaceuticals. Moreover, the biological systems require careful selection of microbial consortium to efficiently eradicate or reduce the concentration of pharmaceuticals without having their adverse effects on the microorganisms. Therefore, in this chapter, the commonly used conventional (activated sludge process) and available technologies to eradicate pharmaceuticals from wastewater (WW) were discussed. Further novel method and advance treatment options to remove pharmaceuticals from the effluents were discussed in details. The removal mechanisms of pharmaceuticals, mainly sorption or biodegradation process and the impact parameters were elaborated. Moreover, the insights of the engineering aspects to improve the treatment efficiency of the pharmaceuticals were presented. For the stake holder, the insights of the technical and economic evaluation of the biological process were provided. In addition to pharmaceuticals WW generated from industries, the small flows generated from the healthcare centers (i.e., from pathology laboratories, private dental establishment, etc.), and their effect on the environment and the necessary measure were deliberated. Moreover, the consequences of climate change on the WWTPs and pathogen survival were well explained. Finally, the challenges to be addressed in mere future were detailed.
Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without p... more Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without pre-treatment, were assessed using mass-energy balance and the corresponding greenhouse gas (GHG) emissions. For a digestion period of 30 days, volatile solids degradation of the control sludge and the ultrasonicated secondary sludge was 51.4% and 60.1%, respectively. Mass balance revealed that the quantity of digestate required for dewatering, transport and land application was the lowest (20.2 × 10(6) g dry sludge/day) for ultrasonicated secondary sludge at 31.4 g TS/L. Furthermore, for ultrasonicated secondary sludge at 31.4 g TS/L, the maximum net energy (energy output - energy input) of total dry solids (TDS) was 7.89 × 10(-6) kWh/g and the energy ratio (output/input) was 1.0. GHG emissions were also reduced with an increase in the sludge solids concentration (i.e., 40.0 g TS/L < 30.0 g TS/L < 20.0 g TS/L). Ultrasonication pre-treatment proved to be efficient and beneficial for enhancing anaerobic digestion efficiency of the secondary sludge when compared to the primary and mixed sludge.
Uploads
Papers by Sridhar Pilli