Demonstrating PM2.5 and road-side dust pollution by heavy metals along Thika superhighway in Kenya, sub-Saharan Africa

This study assessed the level of heavy metal in roadside dust and PM2.5 mass concentrations along Thika superhighway in Kenya. Thika superhighway is one of the busiest roads in Kenya, linking Thika town with Nairobi. Triplicate road dust samples collected from 12 locations were analysed for lead (Pb), chromium (Cr), cadmium (Cd), nickel (Ni), zinc (Zn), and copper (Cu) using atomic absorption spectrophotometry (AAS). PM2.5 samples were collected on pre-weighed Teflon filters using a BGI personal sampler and the filters were then reweighed. The ranges of metal concentrations were 39–101 μg/g for Cu, 95–262 μg/g for Zn, 9–28 μg/g for Cd, 14–24 μg/g for Ni, 13–30 μg/g for Cr, and 20–80 μg/g for Pb. The concentrations of heavy metals were generally highly correlated, indicating a common anthropogenic source of the pollutants. The results showed that the majority of the measured heavy metals were above the background concentration, and in particular, Cd, Pb, and Zn levels indicated moderate to high contamination. Though not directly comparable due to different sampling timeframes (8 h in this study and 24 h for guideline values), PM2.5 for all sites exceeds the daily WHO PM2.5 guidelines of 25 μg/m3. This poses a health risk to people using and working close to Thika superhighway, for example, local residents, traffic police, street vendors, and people operating small businesses. PM2.5 levels were higher for sites closer to Nairobi which could be attributed to increased vehicular traffic towards Nairobi from Thika. This study provides some evidence of the air pollution problem arising from vehicular traffic in developing parts of the world and gives an indication of the potential health impacts. It also highlights the need for source apportionment studies to determine contributions of anthropogenic emissions to air pollution, as well as long-term sampling studies that can be used to fully understand spatiotemporal patterns in air pollution within developing regions

Removal of selected antibiotics and antiretroviral drugs during post‐treatment of municipal wastewater with UV, UV/chlorine and UV/hydrogen peroxide

Active pharmaceutical ingredients (APIs) are only partially removed by convectional wastewater treatment plants. This study aimed at assessing the post‐treatment degradation of selected antibiotics and antiretroviral drugs by direct UV photolysis and advanced oxidation processes (UV/H2O2 and UV/Cl2) using low‐pressure mercury lamp. The rate of degradation largely followed pseudo first‐order reaction kinetics. Amongst the six studied APIs, sulfamethoxazole, ciprofloxacin and zidovudine were readily degraded by more than 90% using direct UV photolysis. Addition of Cl2 and H2O2 to the UV process led to an increase in the rate of degradation for all the compounds. The effectiveness UV/Cl2 process was affected to a greater extent by the background effluent organic matter. This implies that higher electrical energy and oxidant would be required in the UV/Cl2 process relative to UV/H2O2 process. Generally, electrical energy required to remove 90% of the target compounds increased in the order UV/H2O2 < UV/Cl2 < UV processes.peerReviewe

A multiresidue analytical method for trace level determination of antibiotics and antiretroviral drugs in wastewater and surface water using SPE-LC-MS/MS and matrix-matched standards

An analytical method for simultaneous determination of seven commonly used antibiotics and three antiretrovirals in surface water and urban wastewater at the ng L−1 level has been developed. The method involves concentration and clean-up by solid phase extraction (SPE) followed by identification and quantification by liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS). The use of matrix-matched calibration curves constructed by spiking surface water was evaluated for quantification and compared with the internal standard method using isotopically labelled compounds. The method gave absolute recoveries of 41–116% with most of the compounds having recoveries >50%. The LOQs ranged from 5 to 63 ng L−1 allowing for the determination of the analytes at trace levels in the environmental samples considered. The difference in the quantification results obtained using surface water matrix-matched standards and internal standards was within a ±20% margin. The method provides an affordable and relatively fast alternative with acceptable accuracy and precision. The method was applied to study the occurrence of the target analytes in the surface water of Lake Päijänne and wastewater from the Jyväskylä wastewater treatment plant (WWTP) in Central Finland. All target compounds were detected in the WWTP streams with concentrations ranging between 10 and 570 ng L−1 while low ng L−1 levels were measured for some of the analytes in surface waters. The results institute the need for further monitoring in other WWTP streams and receiving waters as well as improvements of the wastewater treatment process with the aim of minimizing the pharmaceutical load in the effluents.peerReviewe

Characteristics of Microcrystalline Cellulose from Coir Fibers

This work aimed to extract and characterize microcrystalline cellulose from coir fibers. Extraction was achieved in a two-step process in which the coir fibers were treated with sodium hydroxide for 3 h at 100°C followed by bleaching with peracetic acid to remove residual lignin and hemicellulose. The microcrystalline cellulose powder characteristics such as the bulk density, tapped density, angle of repose and swelling ratio were found to be 0.08 ± 0.00 g/cm3, 0.12 ± 0.0 g/cm3, 38° and 8.15 ± 0.14 g/g, respectively. Fourier transform infrared spectroscopy exhibited characteristic microcrystalline cellulose peaks. The degree of crystallinity microcrystalline cellulose was found to be 39.5% as determined by X-ray diffraction analysis. The Differential scanning calorimetry and Thermogravimetric analysis revealed that the glass transition and onset of degradation temperature for microcrystalline cellulose were 206°C and 196°C, respectively. From the results, it was concluded that the coir fibers could be a good source of microcrystalline cellulose for applications in the binder, pharmaceutical, and paper making industries due to its powder properties, good swelling, and compressibility

Occurrence of antibiotics and antiretroviral drugs in source-separated urine, groundwater, surface water and wastewater in the peri-urban area of Chunga in Lusaka, Zambia

Recently, there has been an increased interest in bridging the knowledge gap in the occurrence and fate of pharmaceuticals in African urban water cycles. In this study, the occurrence of 7 antibiotics and 3 antiretrovirals in source-separated urine, groundwater, wastewater and surface water of the peri-urban area of Chunga in Lusaka, Zambia, was studied. In groundwater, the pharmaceuticals were only sporadically present with 4 antibiotics and 1 antiretroviral detected. The concentration of the antibiotics ranged from below limit of quantification (peerReviewe

Contamination of Surface Water and River Sediments by Antibiotic and Antiretroviral Drug Cocktails in Low and Middle-Income Countries : Occurrence, Risk and Mitigation Strategies

Presence of antimicrobial cocktails in the hydrological cycles is of interest because of their potential to mediate antimicrobial resistance within the natural environment. In this study, we determined the concentrations of selected antibiotics and antiretroviral drugs (ARVDs) in wastewater treatment plant (WWTP) effluent, effluent suspended particulate matter (SPM), surface waters and river sediments in Kenya in order to determine the extent of pollution within the sampled environment. Target analysis for the most common antibiotics and ARVDs was done. Sulfamethoxazole (SMX), ciprofloxacin (CIP), trimethoprim (TMP), norfloxacin (NOR), zidovidine (ZDV), lamivudine (3TC) and nevirapine (NVP) were analyzed using LC-ESI-MS/MS. Effluent aqueous phase had concentrations ranging between 1.2 µg L−1 to 956.4 µg L−1 while the effluent SPM showed higher concentrations, ranging between 2.19 mg Kg−1 and 82.26 mg Kg−1. This study shows emission of active pharmaceutical ingredients (APIs) from WWTP to the environment mainly occurs via the SPM phase, which is usually overlooked in environmental analyses. Concentrations in surface waters and river sediments ranged between 1.1 µg L−1 to 228 µg L−1 and 11 µg Kg−1 to 4125 µg Kg−1 respectively. ARVDs occurred at consistently higher concentrations than antibiotics in both the aqueous and solid samples. The wastewater treatment plants and lagoons where sludge degradation should occur, are sources of active pharmaceutical ingredients (APIs) including transformational products, nutrients and organic matter that are released back to the aqueous phase.peerReviewe

Pharmaceuticals and personal care products in the aquatic environment : how can regions at risk be identified in the future?

Pharmaceuticals and personal care products (PPCPs) are an indispensable component of a healthy society. However, they are well established environmental contaminants, and many can elicit biological disruption in exposed organisms. It is now a decade since the Society of Environmental Toxicology and Chemistry (SETAC) published its landmark review of PPCPs in the environment (Boxall et al., 2012). Here we discuss key research priorities for the next 10 years with an aim on how regions where PPCPs pose the greatest risk to environmental and human health, either now or in the future, can be identified. Specifically, we discuss why this problem is of importance and review our current understanding of PPCPs in the aquatic environment. Foci include PPCP occurrence and what drives their environmental emission as well as our ability to both quantify and model their distribution. We highlight critical areas for future research including the involvement of citizen science for environmental monitoring and using modelling techniques to bridge the gap between research capacity and needs. As prioritisation of regions in need of environmental monitoring is needed to assess future/current risk, we also propose four criteria with which this may be achieved. Applying these criteria to available monitoring data we narrow the focus on where monitoring efforts for PPCPs are most urgent. Specifically, 19 cities across Africa, Central America, the Caribbean, and Asia were highlighted as priorities for future environmental monitoring and risk characterisation. Together, this informs our suggestion of four priority research questions for the next 10 years

Occurrence of antibiotics and risk of antibiotic resistance evolution in selected Kenyan wastewaters, surface waters and sediments

Active pharmaceutical ingredients, especially antibiotics, are micropollutants whose continuous flow into hydrological cycles has the potential to mediate antibiotic resistance in the environment and cause toxicity to sensitive organisms. Here, we investigated the levels of selected antibiotics in four wastewater treatment plants and the receiving water bodies. The measured environmental concentrations were compared with the proposed compound-specific predicted no-effect concentration for resistance selection values. The concentration of doxycycline, amoxicillin, sulfamethoxazole, trimethoprim, ciprofloxacin and norfloxacin within the influents, effluents, surface waters and river sediments ranged between 0.2 and 49.3 μgL−1, 0.1 to 21.4 μgL−1; ˂ 0.1 and 56.6 μgL−1; and 1.8 and 47.4 μgkg−1, respectively. Compared to the effluent concentrations, the surface waters upstream and downstream one of the four studied treatment plants showed two to five times higher concentrations of ciprofloxacin, norfloxacin and sulfamethoxazole. The risk quotient for bacterial resistance selection in effluent and surface water ranged between ˂0.1 and 53, indicating a medium to high risk of antibiotic resistance developing within the study areas. Therefore, risk mitigation and prevention strategies are a matter of priority in the affected areas.peerReviewe

Influence of Transesterification Catalysts Synthesized with Citric Acid on the Quality and Oxidative Stability of Biodiesel from Black Soldier Fly Larvae

In biodegradable waste management, use of Black Soldier Fly Larvae (BSFL) is a promising method for bioconversion of waste into crude insect fat as feedstock for biodiesel production. Biodiesel is a renewable alternative to fossil fuel, but it is more susceptible to oxidative degradation over long-term storage. This study investigates the effectiveness of NaOH and CaO catalysts synthesized with citric acid (CA) in improving the oxidative stability of biodiesel. The biodiesel and biodiesel/diesel blends derived from BSFL were stored at 63 °C for 8 days. The quality of biodiesel was determined by analysis of the physicochemical and fuel properties by: Fourier transform infrared (FTIR) spectroscopy, ultraviolet visible spectrophotometer (UV-Vis), gas chromatography-mass spectroscopy (GC-MS), bomb calorimeter and titration methods. Properties that were analyzed included: peroxide value, acid value, iodine value, refractive index, density, calorific value, total oxidation (TOTOX), anisidine value and fatty acid profile. The results showed that catalysts synthesized with CA retarded the decomposition of unsaturated fatty acids, resulting in a significant delay in the formation of hydroperoxides. Besides, 10-oxo-octadecanoic acid, an antioxidant, was present in biodiesel produced using catalysts synthesized with CA, hence enhancing the stability of biodiesel against oxidation. Catalysts synthesized with CA slowed the decomposition of monounsaturated fatty acids by 6.11–11.25%. Overall, biodiesel produced using catalysts synthesized with CA was observed to degrade at a slower rate than biodiesel produced using commercial calcium oxide. The reduced degradation rates demonstrate the effectiveness of the synthesized catalysts in enhancing the oxidation stability and consequently the fuel qualities of biodiesel from BSFL under accelerated storage

Mass loading, distribution, and removal of antibiotics and antiretroviral drugs in selected wastewater treatment plants in Kenya

The discharge of active pharmaceutical ingredients (APIs) into the aquatic environment from wastewater effluents is a concern in many countries. Although many studies have been conducted to evaluate the APIs removal efficiencies and emissions to the environment in wastewater treatment plants (WWTPs), most of these studies considered the aqueous and sludge phases, disregarding the suspended particulate matter (SPM) phase. To try to understand the role of the SPM, the occurrence of five most common antibiotics and three antiretroviral drugs (ARVDs) commonly used in Kenya were investigated in this study. APIs partitioning and mass loading in influents and effluents of three different WWTPs: trickling filters, stabilization ponds, and decentralized fecal sludge system, were evaluated. API concentration levels ranging from ˂LOQ (limit of quantification) to 92 μgL−1 and ˂LOQ to 82.2 mgkg−1 were observed in aqueous samples and solid samples respectively, with SPM accounting for most of the higher concentrations. The use of the aqueous phase alone for determination of removal efficiencies showed underestimations of API removal as compared to when solid phases are also considered. Negative removal efficiencies were observed, depending on the compound and the type of WWTP. The negative removals were associated with deconjugation of metabolites, aggregated accumulation of APIs in the WWTPs, as well as unaccounted hydraulic retention time during sampling. Compound characteristics, environmental factors, and WWTPs operation influenced WWTPs removal efficiencies. Wastewater stabilization ponds had the poorest removals efficiencies with an average of −322%. High total mass loads into the WWTPs influent and effluent of 22,729 and 22,385 mg day−1 1000 PE−1 were observed respectively. The results aims at aiding scientists and engineers in planning and designing of WWTPs. Findings also aim at aiding policy-making on pharmaceutical drug use and recommend proper wastewater management practices to manage the high mass loading observed in the WWTPs.peerReviewe