Occurrence, distribution, and risk assessment of pharmerciuticals in wastewater and open surface drains of peri-urban areas: Case study of Juja town, Kenya.

The occurrence of Active Pharmaceutical Ingredients (APIs) in the environment is becoming a major area of concern due to their undesirable effects on non-target organisms. This study investigated the occurrence and risk of contamination by five antibiotics and three antiretrovirals drugs in a fast-growing peri-urban area in Kenya, with inadequate sewer system coverage. Due to poor sewage connectivity and poorly designed decentralized systems, wastewater is directly released in open drains. Water and sediment samples were collected from open surface water drains, while wastewater samples were collected from centralized wastewater treatment plants (WWTP). Solid-phase extraction and ultrasonic-assisted extraction for the aqueous and sediment samples respectively were carried out and extracts analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) using isotopically labeled internal standards. APIs were observed with the detection frequency ranging from 36% to 100%. High mean concentrations of 48.7 µg L-1, 108 µg L-1, and 532 µg L-1 were observed in surface drains for Lamivudine (3 TC), Sulfamethoxazole (SMX), Ciprofloxacin (CIP) respectively. Drain sediments also showed high concentrations of APIs ranging from 2.1 to 13,100 µg kg-1. APIs in this study exceeded those observed in existing literature studies. JKUAT WWTP removal efficiencies varied from -90.68% to 72.67%. Total APIs emission load of the study area was 3550 mg d-1 with WWTP effluent contributing higher loads (2620 mg d-1) than surface water drains (640 mg d-1). Zidovudine (ZDV), nevirapine (NVP), and trimethoprim (TMP) loads in drains, however, exceeded WWTP effluent. Low to high ecotoxicity risk of the individual APIs were observed to the aquatic environment, with high risks for the development of antibiotic resistance in microbiome as determined by the risk quotient (RQ) approach. Risk management through efficient wastewater collection, conveyance, and treatment is necessary to suppress the measured concentrations.

The effect of urine storage on antiviral and antibiotic compounds in the liquid phase of source-separated urine.

The behaviour of pharmaceuticals related to the human immunodeficiency virus treatment was studied in the liquid phase of source-separated urine during six-month storage at 20°C. Six months is the recommended time for hygienization and use of urine as fertilizer. Compounds were spiked in urine as concentrations calculated to appear in urine. Assays were performed with separate compounds and as therapeutic groups of antivirals, antibiotics and anti-tuberculotics. In addition, urine was amended either with faeces or urease inhibitor. The pharmaceutical concentrations were monitored from filtered samples with solid phase extraction and liquid chromatography. The concentration reductions of the studied compounds as such or with amendments ranged from less than 1% to more than 99% after six-month storage. The reductions without amendments were 41.9-99% for anti-tuberculotics; <52% for antivirals (except with 3TC 75.6%) and <50% for antibiotics. In assays with amendments, the reductions were all <50%. Faeces amendment resulted in similar or lower reduction than without it even though bacterial activity should have increased. The urease inhibitor prevented ureolysis and pH rise but did not affect pharmaceutical removal. In conclusion, removal during storage might not be enough to reduce risks associated with the studied pharmaceuticals, in which case other feasible treatment practises or urine utilization means should be considered.

Bacterial diversity and active biomass in full-scale granular activated carbon filters operated at low water temperatures.

Granular activated carbon (GAC) filtration enhances the removal of natural organic matter and micropollutants in drinking water treatment. Microbial communities in GAC filters contribute to the removal of the biodegradable part of organic matter, and thus help to control microbial regrowth in the distribution system. Our objectives were to investigate bacterial community dynamics, identify the major bacterial groups, and determine the concentration of active bacterial biomass in full-scale GAC filters treating cold (3.7-9.5°C), physicochemically pretreated, and ozonated lake water. Three sampling rounds were conducted to study six GAC filters of different operation times and flow modes in winter, spring, and summer. Total organic carbon results indicated that both the first-step and second-step filters contributed to the removal of organic matter. Length heterogeneity analysis of amplified 16S rRNA genes illustrated that bacterial communities were diverse and considerably stable over time. α-Proteobacteria, ß-Proteobacteria, and Nitrospira dominated in all of the GAC filters, although the relative proportion of dominant phylogenetic groups in individual filters differed. The active bacterial biomass accumulation, measured as adenosine triphosphate, was limited due to low temperature, low flux of nutrients, and frequent backwashing. The concentration of active bacterial biomass was not affected by the moderate seasonal temperature variation. In summary, the results provided an insight into the biological component of GAC filtration in cold water temperatures and the operational parameters affecting it.

Simultaneous detection of three antiviral and four antibiotic compounds in source-separated urine with liquid chromatography.

An analytical method for the simultaneous screening of three antiviral agents (nevirapine, zidovudine, lamivudine), four antibiotics (sulfamethoxazole, trimethoprim, ciprofloxacin, rifampicin) and one reference compound (carbamazepine) in human urine was developed. Separation was achieved with a Kinetex XB-C18 (75 × 4.6 mm, 2.6 µm) column after the extraction of pharmaceuticals from urine with SPE. Gradient elution with a mobile phase consisting of acetonitrile and 10 mM KH2 PO4 (pH 2.5), and diode array detection with monitoring at 210 and 264 nm was applied. The developed method was validated in terms of selectivity, linearity, stability and sensitivity. Repeatability (n = 3) and between-day precision (n = 3) revealed RSD <5%. The detection limits were estimated as 0.02-0.54 g/L (depending on compound). The method was validated for human urine and successfully applied to the simultaneous quantification of selected compounds. Strata-X cartridges provided good recoveries ranging from 81 to 109%. The limits of detection for urine varied between 0.04 and 1.61 g/L. The method is suitable for the fast determination of selected pharmaceuticals from source-separated urine samples for further environmental risk assessment and degradation potential evaluation. It provides a way to enhance safe nutrient recycling from wastewater streams and promotes the safe use of urine as fertiliser.