Josip Ćurko

Removal of antimicrobials using advanced wastewater treatment

Removal of numerous classes of pharmaceuticals from the municipal and industrial wastewater, using conventional wastewater treatment, is incomplete and several studies suggested that improvement of this situation would require the application of advanced treatment techniques. This is particularly important for the treatment of industrial effluents, released from pharmaceutical industries, which can contain rather high concentrations of antimicrobials. The aim of this work was to evaluate membrane bioreactors (MBRs), nanofiltration, reverse osmosis and ozonation, as well as their combinations, for the removal of antimicrobials from a synthetic wastewater which simulated highly contaminated industrial effluents. The study was performed using a mixture of four important classes of antimicrobials, including sulfonamides (SA), fluoroquinolones (FQ), macrolides (MAC) and trimethoprim (TMP). Performance of two different types of MBRs, Kubota and Zenon, was evaluated under different regimes regarding hydraulic retention time, total organic load and total nitrogen load. It was shown that elimination of SA in MBR treatment was very efficient, while the elimination of MAC, FQ, and TMP was incomplete. A mass balance of these contaminants in MBR suggested that microbial transformation represented the main mechanism, while only a small percentage was eliminated from the aqueous phase by adsorption onto sludge particles. Nanofiltration and reverse osmosis achieved high elimination rates however produced highly contaminated concentrate. High removal was achieved using ozonation, but further research is needed to characterize formed ozonation products.

Treatment of spent filter backwash water from drinking water treatment with immersed ultrafiltration membranes

Abstract The purpose of this study was to investigate characteristics of treatment of spent filter backwash water (SFBW) from two full-scale drinking water treatment plants (WTPs) with immersed ultrafiltration membranes in order to achieve reuse of permeate. During this study, 10% of daily generated SFBW from the treatment plants in Croatia were treated on two pilot-scale UF plants. Three different types of immersed membranes were employed and operated with fluxes, which ranged from 10 to 54 L/m2 h in two continuous experiments, which lasted 75 and 96 days. During both experiments, transmembrane pressure, flux, and turbidity of filtrate were constantly measured. Rate of membrane fouling was very slow, and no chemical cleaning was needed but the membranes were regularly relaxed. Turbidity of permeate was always below 0.5 NTU. Results confirmed that permeate could be reused either for backwashing of sand filters, or as a source of raw water for drinking water treatment process.

Effectiveness of UV-C light irradiation on disinfection of an eSOS® smart toilet evaluated in a temporary settlement in the Philippines

Abstract Ultraviolet germicidal (short wavelength UV-C) light was studied as surface disinfectant in an Emergency Sanitation Operation System® smart toilet to aid to the work of manual cleaning. The UV-C light was installed and regulated as a self-cleaning feature of the toilet, which automatically irradiate after each toilet use. Two experimental phases were conducted i.e. preparatory phase consists of tests under laboratory conditions and field testing phase. The laboratory UV test indicated that irradiation for 10 min with medium–low intensity of 0.15–0.4 W/m2 could achieve 6.5 log removal of Escherichia coli. Field testing of the toilet under real usage found that UV-C irradiation was capable to inactivate total coliform at toilet surfaces within 167-cm distance from the UV-C lamp (UV-C dose between 1.88 and 2.74 mW). UV-C irradiation is most effective with the support of effective manual cleaning. Application of UV-C for surface disinfection in emergency toilets could potentially reduce public health risks.