Ivan Mijatović

Membrane bioreactor (MBR) as an advanced wastewater treatment technology

The development and application of a membrane bioreactor (MBR) for full- scale municipal wastewater treatment is the most important recent technological advance in terms of biological wastewater treatment. The MBR is a suspended growth-activated sludge system that utilizes microporous membranes for solid/liquid separation instead of secondary clarifiers. It represents a decisive step forward concerning effluent quality by

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 a landfill leachate containing compounds of pharmaceutical origin

Paper reports the results of landfill leachate treatment with membrane bioreactor, nanofiltration and ozonation. Investigated leachate encompasses a number of specific compounds of pharmaceutical origin, including a suite of by-products deriving from the production of vitamin C and propyphenazone. Low biodegradability was observed in MBR (16%) for propyphenazone, while the removal of intermediates from the vitamin C-synthesis was moderate, reaching 30% for diacetone sorbose (DAS) and 69% for diacetone alpha-keto-gulonic acid (DAG). Ozonation almost completely removed propyphenazone but failed to significantly oxidise intermediates from the vitamin C-synthesis. Nanofiltration of the leachate succeeded to remove 99% of DAG and 79% of propyphenazone which made it the most efficient among techniques used.

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.