Electrochemical Treatment of Effluent for the Removal of Contaminants of Emergent Concern and Culturable Microorganisms

The present work aims to study the electrochemical (EC) process applied for the removal of contaminants of emergent concern (CECs) from wastewater after secondary treatment and the effect of the process on the total culturable microorganisms. The EC experiments were performed in a cylindrical open reactor with 500 mL of effluent, and a fixed current density of 8 mA/cm² was applied through mixed metal oxide electrodes. The experiments were conducted in different sets. In the first round (Set 1), the effluent sample was spiked with three CECs (200 ppb each): caffeine (CAF), carbamazepine (CBZ), and oxybenzone (OXY). For the best treatment period, 6 h, electrodegradation rates ranged from 41 ± 7% for CAF to 95 ± 6% for OXY, with an 87% removal of total culturable microorganisms. In the second round (Set 2), aiming to assess EC process efficiency in a more complex CEC mixture, the effluent was spiked with six more CECs (200 ppb each): diclofenac (DCF), triclosan (TCS), bisphenol A (BPA), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and ibuprofen (IBU), giving a total of nine CECs. In this case, the EC process allowed decreasing the CEC content by 19–100% (below the limit of detection), depending on the effluent samples, and the culturable microorganisms by 99.98% after a 6 h treatment. By contributing to CEC degradation and microorganism removal, the EC process proved to be a viable remediation and disinfection technology for secondary effluent from wastewater treatment plants.

Biosand Filter as a Point-of-Use Water Treatment Technology: Influence of Turbidity on Microorganism Removal Efficiency

The number of people living without access to clean water can be reduced by the implementation of point-of-use (POU) water treatment. Among POU treatment systems, the domestic biosand filter (BSF) stands out as a viable technology. However, the performance of the BSF varies with the inflow water quality characteristics, especially turbidity. In some locations, people have no choice but to treat raw water that has turbidity above recommended levels for the technology. This study aimed to measure the efficiency with which the BSF removes microorganisms from well water and from fecal-contaminated water with turbidity levels of 3, 25, and 50 NTU. Turbidity was controlled by the addition of kaolin to water. Turbidity removal varied from 88% to 99%. Reductions in total coliform (TC) and Escherichia coli ranged from 0.54–2.01 and 1.2–2.2 log removal values (LRV), respectively. The BSF that received water with a higher level of turbidity showed the greatest reduction in the concentration of microorganisms. Additional testing with water contaminated with four bacterial pure cultures showed reductions between 2.7 and 3.6 LRV. A higher reduction in microorganisms was achieved after 30–35 days in operation. Despite the filter’s high efficiency, the filtrates still had some microorganisms, and a disinfection POU treatment could be added to increase water safety.

Pollutant and Microorganism Removal From Water by Hydrodynamic Cavitation

Hydrodynamic cavitation can effectively remove organic pollutants and microorganisms from water. Organic compound degradation and water disinfection removal rate is related to reaction time and operating temperature. Removal rate can be improved by increasing the reaction time or raising the operating temperature. Under our experimental conditions, the removal rate of colority, COD and petroleum pollutants was 80.0%, 72.13% and 70.00%, respectively. In addition, Escherichia coli removal rate was higher than 99.99%. As a new water treatment process, hydrodynamic cavitation can be utilized alone or in combination with other water treatment processes, showing broad application prospects.

Direct potable reclamation in Windhoek: a critical review of the design philosophy of new Goreangab drinking water reclamation plant

Direct drinking water reclamation from the Goreangab reclamation plant, has been a reality in Windhoek, Namibia since 1968. Potable reclamation is a fixed part of the water supply and waste water has become an indispensible resource for the survival and continued growth of the city. The multi barrier concepts that were applied 40 years ago have been refined over many years. Improvements in water treatment technology have made it possible to improve the reliability and the drinking water quality of the reclamation treatment process. With the latest upgrade, which was designed 14 years ago and commissioned in 2002, a specific design philosophy was followed. This paper will assess whether the objectives of the design philosophy have been met in terms of removal efficiencies and safety of drinking water, which contains at present 25% reclaimed water. The basis and aims of the multi barrier design that was applied is discussed and with the aid of natural organic matter (NOM) and microorganism removal, the reliability of the philosophy is tested and compared with the goals set. Comparisons are drawn between the new plant and the previous plant and how the new plant is able to accommodate changes in raw water quality. It can be concluded that the water quality has been improved and the barrier principle does reduce the risk and improve the water quality.

Surface Modification of Micro/Nano-Fabricated Filters

Polymeric Micro-Fabricated Filters Have Excellent Sieving Properties. Their Identical Properties such as High Surface Porosity and Perfectly Patterned Pore Structure, which Is Combined with Mechanical Strength Make them Ideal for many Applications such as Microorganism Removal, Blood Filtration and Protein Purification. To Improve the Performance of the Micro-Fabricated Filters, we Employed Oxygen Plasma Treatment to Increase the Surface Hydrophilicity and Reduce the Membrane Fouling during Microfiltration. Hydrophilization and Integrity of the Surfaces Were Analyzed by Contact Angle Measurements and Topographic Imaging with an Atomic Force Microscope (AFM). Treatment of Polymeric Membranes with Oxygen Plasma Led to a Stable Hydrophilization and an Increased Surface Roughness. The Filtration Properties of the Modified and Unmodified Membranes Were Examined Using Clay Particles. A Significant Increase in Total Collected Volume of Filtrate Was Observed for the Treated Membranes during Filtration of Simulated Drinking Water Samples Using Clay Suspension.