Sahar Dalahmeh

Hygienic quality of artificial greywater subjected to aerobic treatment: a comparison of three filter media at increasing organic loading rates.

With a growing world population, the lack of reliable water sources is becoming an increasing problem. Reusing greywater could alleviate this problem. When reusing greywater for crop irrigation it is paramount to ensure the removal of pathogenic organisms. This study compared the pathogen removal efficiency of pine bark and activated charcoal filters with that of conventional sand filters at three organic loading rates. The removal efficiency of Escherichia coli O157:H7 decreased drastically when the organic loading rate increased fivefold in the charcoal and sand filters, but increased by 2log 10 in the bark filters. The reduction in the virus model organism coliphage ΦX174 remained unchanged with increasing organic loading in the charcoal and sand filters, but increased by 2log 10 in the bark filters. Thus, bark was demonstrated to be the most promising material for greywater treatment in terms of pathogen removal.

Quality of greywater treated in biochar filter and risk assessment of gastroenteritis due to household exposure during maintenance and irrigation

This study evaluated treatment of greywater (GW) by a biochar filter in Jordan and assessed the annual risks of infection (Pi‐annual), annual risk of disease (Pd‐annual) and disease burden (in disability‐adjusted life years; DALYs) of gastroenteritis caused by Salmonella spp. and rotavirus due to ingestion of GW during system maintenance and consumption of green onions irrigated with treated and nontreated GW.

Simulation and verification of hydraulic properties and organic matter degradation in sand filters for greywater treatment

To evaluate the treatment performance of vertical flow sand filters, the HYDRUS wetland module was used to simulate treatment in an experimental set-up. The laboratory filters were intermittently dosed with artificial greywater at a hydraulic loading rate of 0.032 m³ m⁻² day⁻¹ and an organic loading rate of 0.014 kg BOD5 m⁻² day⁻¹. The hydraulic properties of the filter were characterised, as were inflow and outflow concentrations of chemical oxygen demand (COD), biochemical oxygen demand (BOD), ammonia, nitrate and total nitrogen. The inverse simulation function of the HYDRUS software was used to calibrate the water flow model. The observed effect of water flowing faster along the column wall was included in the inverse simulations. The biokinetic model was calibrated by fitting heterotrophic biomass growth to measurements of potential respiration rate. Emphasis was put on simulating outflow concentrations of organic pollutants. The simulations were conducted using three models of varying degree of calibration effort and output accuracy. The effluent concentration was 245 mg COD L⁻¹ for the laboratory filters, 134 mg COD mg L⁻¹ for the model excluding wall flow effects and 338 mg COD mg L⁻¹ for the model including wall flow effects.

Potential of biochar filters for onsite sewage treatment: Adsorption and biological degradation of pharmaceuticals in laboratory filters with active, inactive and no biofilm

This study investigated the potential of biochar filters as a replacement or complement for sand filters for removal of pharmaceutically active compounds (PhACs) from wastewater in onsite sewage facilities (OSSF). Specifically, the study investigated the effects of biodegradation, adsorption and a combination of these processes on removal of four model PhACs from wastewater in biochar filters operated under hydraulic loading conditions mimicking those found in onsite infiltration beds. Concentrations and removal of the four PhACs (i.e. carbamazepine, metoprolol, ranitidine and caffeine) were investigated over 22weeks in four treatments: biochar (BC) with active or inactive biofilm (BC-active-biofilm, BC-inactive-biofilm), biochar without biofilm (BC-no-biofilm) and sand with active biofilm (Sand-active-biofilm). The adsorption of carbamazepine was high in BC-no-biofilm (99% removal after 22weeks), while biodegradation was very low in Sand-active-biofilm (7% removal after 22weeks). Removal of carbamazepine in BC-active-biofilm was high and stable over the 22weeks (>98%), showing a significant role of biofilm in filter biogeneration. However, carbamazepine removal declined over time in BC-inactive-biofilm, from 99% in week 13 to 73% in week 22. Metoprolol was poorly degraded in Sand-active-biofilm (37% after 22weeks), while adsorption seemed to be the major pathway for removal of metoprolol in biochar. Ranitidine and caffeine were efficiently removed by either adsorption (97% and 98%, respectively, after 22weeks) or biodegradation (99% and >99%, respectively, after 22weeks). In conclusion, biochar is a promising filter medium for OSSF, especially for persistent PhACs such as carbamazepine and metoprolol.

Per- and polyfluoroalkyl substances (PFASs) in water, soil and plants in wetlands and agricultural areas in Kampala, Uganda

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 (5.6-9.1ngL-1) than in the corresponding influent (3.4-5.1ngL-1), indicating poor removal of PFASs within the WWTP. ∑PFAS concentrations decreased by a factor of approximately five between Nakivubo channel (8.5-12ngL-1) and Lake Victoria (1.0-2.5ngL-1), due to dilution, sorption to sediment and uptake by plants in the wetland. ∑PFAS concentrations were within the range 1700-7900pgg-1 dry weight (dw) in soil and 160pgg-1 dw (maize cobs) to 380pgg-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 Kd) in wetland soil under yam was lowest for short-chain PFHxA (1.9-2.3Lkg-1) and increased with increasing chain length to 2.8-3.1Lkg-1 for perfluoroundecanoate (PFUnDA) and 2.8-3.1Lkg-1 for perfluoroctanesulfonate (PFOS). The log Koc values ranged between 2.2 and 3.6Lkg-1, with the highest log Koc estimated for long-chain perfluorocarbon PFASs (i.e. PFUnDA 3.2-3.5Lkg-1 and PFOS 3.2-3.6Lkg-1). The concentration ratio (CR) between plants and soil was <1 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. Overall, this investigation demonstrated PFASs entry into the terrestrial food chain and drinking water resources in Kampala, Uganda. Source identification, assessment of impacts on human health and the environment, and better wastewater treatment technologies are needed.