Christian Kazner

Comparison of two treatments for the removal of selected organic micropollutants and bulk organic matter: conventional activated sludge followed by ultrafiltration versus membrane bioreactor

The potential of membrane bioreactor (MBR) systems to remove organic micropollutants was investigated at different scales, operational conditions, and locations. The effluent quality of the MBR system was compared with that of a plant combining conventional activated sludge (CAS) followed by ultrafiltration (UF). The MBR and CAS-UF systems were operated and tested in parallel. An MBR pilot plant in Israel was operated for over a year at a mixed liquor suspended solids (MLSS) range of 2.8-10.6 g/L. The MBR achieved removal rates comparable to those of a CAS-UF plant at the Tel-Aviv wastewater treatment plant (WWTP) for macrolide antibiotics such as roxythromycin, clarithromycin, and erythromycin and slightly higher removal rates than the CAS-UF for sulfonamides. A laboratory scale MBR unit in Berlin - at an MLSS of 6-9 g/L - showed better removal rates for macrolide antibiotics, trimethoprim, and 5-tolyltriazole compared to the CAS process of the Ruhleben sewage treatment plant (STP) in Berlin when both were fed with identical quality raw wastewater. The Berlin CAS exhibited significantly better benzotriazole removal and slightly better sulfamethoxazole and 4-tolyltriazole removal than its MBR counterpart. Pilot MBR tests (MLSS of 12 g/L) in Aachen, Germany, showed that operating flux significantly affected the resulting membrane fouling rate, but the removal rates of dissolved organic matter and of bisphenol A were not affected.

Removal of endocrine disruptors and cytostatics from effluent by nanofiltration in combination with adsorption on powdered activated carbon

Direct capillary nanofiltration also in combination with an upstream powdered activated carbon treatment was tested for high quality water reuse of tertiary effluent from a municipal wastewater treatment plant. Two endocrine disruptors (BPA and EE2) and two cytostatics (CytR and 5-FU) were spiked in concentrations of 1 to 2 microg/L to evaluate the process performance. In direct NF the real total removal of the micropollutants was between 5 and 40%. Adsorption to the membrane played a major role leading to a seemingly total removal between 35 and 70%. Addition of powdered activated carbon and lignite coke dust largely reduced the influence from adsorption to the membrane and increased the total removal to >95 to 99.9% depending on the PAC type and dose. The cytostatics showed already in direct NF a very high removal due to unspecified losses. Further investigations are ongoing to understand the underlying mechanism. The PAC/NF process provided a consistently high permeate quality with respect to bulk and trace organics.

Comparing the effluent organic matter removal of direct NF and powdered activated carbon/NF as high quality pretreatment options for artificial groundwater recharge

Direct nanofiltration and nanofiltration combined with powdered activated carbon known as the PAC/NF process were tested regarding the removal of effluent organic matter for reclamation of tertiary effluent from a municipal wastewater treatment plant. They can be regarded as a promising treatment alternative for high quality water reuse applications, especially for direct injection. The total removal for DOC was above 90% with permeate concentrations below 0.5 mg/l. Size exclusion chromatography and fluorescence EEM proved to trace origin of the organic matter even in low concentration ranges. The type and dosage of adsorbent influences the process performance significantly and allows process optimization.

Forward osmosis for the treatment of reverse osmosis concentrate from water reclamation : process performance and fouling control

While high quality water reuse based on dual membrane filtration (membrane filtration or ultrafiltration, followed by reverse osmosis) is expected to be progressively applied, treatment and sustainable management of the produced reverse osmosis concentrate (ROC) are still important issues. Forward osmosis (FO) is a promising technology for maximising water recovery and further dewatering ROC so that zero liquid discharge is produced. Elevated concentrations of organic and inorganic compounds may act as potential foulants of the concentrate desalting system, in that they consist of, for example, FO and a subsequent crystallizer. The present study investigated conditions under which the FO system can serve as concentration phase with the focus on its fouling propensity using model foulants and real ROC. Bulk organics from ROC consisted mainly of humic acids (HA) and building blocks since wastewater-derived biopolymers were retained by membrane filtration or ultrafiltration. Organic fouling of the FO system by ROC-derived bulk organics was low. HA was only adsorbed moderately at about 7% of the initial concentration, causing a minor flux decline of about 2-4%. However, scaling was a major impediment to this process if not properly controlled, for instance by pH adjustment or softening.

Managed aquifer recharge with reclaimed water: approaches to a European guidance framework

Managed Aquifer Recharge (MAR) with reclaimed water plays a particular role in water stress mitigation, due to both the large potential benefits achieved in terms of sustainable water resources management as well as the complexity of the planning and implementation. This paper focuses on the role of policy in establishing water quality related legal frameworks that are crucial for MAR development. It analyses and compares the current practice of shaping boundary conditions, particularly in a European context but with some international comparison. The work reports on the legal aspects considered most relevant for MAR in the European Union and summarises issues addressed in aquifer recharge regulations and guidelines. Some potential actions are proposed to develop a suitable guidance framework for further exploitation of MAR benefits.

Capillary nanofiltration coupled with powdered activated carbon adsorption for high quality water reuse

Direct capillary nanofiltration was tested for reclamation of tertiary effluent from a municipal wastewater treatment plant. This process can be regarded as a promising treatment alternative for high quality water reuse applications when combined with powdered activated carbon for enhanced removal of organic compounds. The nanofiltration was operated at flux levels between 20 and 25 L/(m2 h) at a transmembrane pressure difference of 2-3 bar for approximately 4,000 operating hours. The study was conducted with PAC doses in the range from 0 to 50 mg/L. The plant removal for DOC ranged from 88-98%. The sulfate retention of the membrane filtration process was between 87 and 96%. The process provided a consistently high permeate quality with respect to organic and inorganic key parameters.

Removal of Selected Organic Micropollutants from WWTP Effluent with Powdered Activated Carbon and Retention by Nanofiltration

The increasing demand of potable water as well as process water is leading to scarcity of readily available water resources in many regions of the world. In order to preserve fresh water resources waste water reclamation can serve as a promising but technically challenging alternative to conventional water sources. Besides pathogens, organic trace pollutants cause major concerns in reclamation schemes. In this project, the removal of four micropollutants, more specifically bisphenol A, 17α-ethinylestradiol, 5-fluorouracil and cytarabine, from municipal wastewater treatment plant (WWTP) effluent was studied in laboratory scale experiments and in spiking experiments in a pilot plant combining sorption to powdered activated carbon (PAC) and retention by capillary nanofiltration (NF). Laboratory scale experiments evaluating adsorption isotherms and kinetics showed decreased adsorption capacities but increased affinities in the presence of natural organic matter. Spiking experiments showed that the combination of adsorption to PAC and NF retains micropollutants significantly better than direct NF. Retention of lipophilic micropollutants was increased up to 99.9%. Therefore, the PAC/NF process can be considered as an effective way to treat WWTP effluent for reuse.

Comparison of Two Treatments for the Removal of Organic Micro-Pollutants: Conventional Activated Sludge (CAS) Followed by Ultrafiltration (UF) vs. Membrane Bioreactor (MBR)

The potential of MBR systems to remove organic micro-pollutants was investigated at different scales, operational conditions, and locations. MBR effluent quality was compared with that of a conventional activated sludge (CAS) plant, followed by ultrafiltration (UF), operated and tested in parallel. A MBR pilot plant in Israel was operated for over a year at an MLSS range of 2.8–10.6 g/L. The MBR achieved removal rates comparable to those of a CASUF plant at the Tel-Aviv WWTP for macrolide antibiotics such as roxythromycin, clarithromycin and erythromycin and slightly higher removal rates than the CAS-UF for sulfonamides. A laboratory scale MBR unit in Berlin – at an MLSS of 6–9 g/L – showed better removal rates for macrolide antibiotics, trimethoprim and 5-tolyltriazole compared to the CAS process of the Berlin WWTP Ruhleben at identical raw wastewater quality. Sulfamethoxazole and 4-tolyltriazole were removed slightly better in the CAS while the benzotriazole removal was more significant. In pilot MBR tests at an MLSS of 12 g/L in Aachen, Germany, operating flux significantly affected the resulting membrane fouling rate, but the removal rate of dissolved organic matter and of bisphenol-A was not affected.

TECHNEAU: Safe Drinking Water from Source to Tap State of the art & Perspectives

The best papers from the three-day conference on Safe Drinking Water from Source to Tap June 2009 in Maastricht are published in this book covering the themes of challenges of the water sector and adaptive strategies, treatment, distribution, risk assessment and risk management, sensors and monitoring, small scale systems, simulation, alternative water supply & sources, consumer involvement, and future drinking water. Worldwide, the water supply sector is facing tremendous challenges. Ever new emerging contaminants and pathogens and aging infrastructures that are vulnerable for deliberate contamination pose a threat to the quality of water supplies. Shortage of good quality and readily treatable resources is increasing due to global warming, urbanisation and pollution from agriculture and industry. Regulators and consumers are becoming more demanding. Techneau - the largest European project on drinking water - addresses these challenges by developing adaptive supply system options and new and improved treatment and monitoring technologies. Future system options to be studied are flexible, small scale and multi-source supplies, utilising non conventional resources like brackish ground water, treated wastewater and urban groundwater. ISBN: 9781843392750 (Print) ISBN: 9781780401782 (eBook)