Swedish Water & Wastewater Association

[This corrects the article DOI: 10.1016/j.nmni.2025.101584.].

This paper discusses the removal of ammonium ions (NH4)+ from raw water using a hydrogel as an adsorbent. The raw water has been obtained from Fesha water treatment plant which is a traditional treatment plant located in Behera. For this purpose, kappa carrageenan/acrylic acid hydrogel (KC/AAc) were prepared via free radical polymerization using gamma irradiation. The effect of irradiation dose and (AAc) concentration on gel content was studied. The formed hydrogel was characterized by FTIR and SEM. The swelling behavior was determined as a function of irradiation dose, and AAc content. The developed hydrogel was used for the removal of (NH4)+ ions. The effects of various operating parameters such as initial pH, contact time, and adsorbent dose on the removal of (NH4)+ ions have been investigated. It was found that the optimum pH value is 5 and the perfect adsorbent dose is 15 gm/L. A fast adsorption rate was observed the equilibrium was reached within 50 min and the maximum removal percent was (52.7%).

We report on a heterodyne terahertz spectrometer based on a fully integrated 557-GHz receiver and a digital fast Fourier transform spectrometer. The receiver consists of a chain of multipliers and power amplifiers, followed by a heterostructure barrier varactor tripler that subharmonically pumps a membrane GaAs Schottky diode mixer. All sub-components are newly developed and optimized with regard to the overall receiver performance such as noise temperature, power consumption, weight and physical size. The receiver works at room temperature, has a double sideband noise temperature as low as 2000 K at a maximum power consumption of 4.5 W with an Allan time of 10 s and a sideband gain ratio of 0.52. The performance of the spectrometer is demonstrated by absorption spectroscopy of H <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$_{2}$</tex></formula> O and CH <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$_{3}$</tex></formula> OH with an instantaneous bandwidth of 1.5 GHz and a resolution of 183 kHz. Several pressure broadening parameters of methanol absorption lines were determined, that agree with other published data. Using the experimentally determined molecular parameters the CH <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$_{3}$</tex> </formula> OH absorption spectrum could be modeled with very high precision.

Historically, the focus concerning emissions of xenobiotics has been on industrial effluents and point sources, but nowadays there is a recognition of the existence of diffuse emissions of hazardous substances from many different sources, including materials and consumer goods. In this chapter different mitigation strategies against such emissions are discussed. Mitigation is here defined as upstream source control. Removal of xenobiotics by sewage treatment methods is not covered. The main focus is on the options that national, regional and local authorities have to reduce emissions of hazardous substances at their sources but other actors, such as businesses and non-governmental organisations, are also discussed. The tools for mitigation include green procurement, use of current legislation, voluntary agreements, cooperation, financial initiatives, information campaigns, ecolabelling, etc. Examples of each tool are given and follow-up and costs are discussed.

Water and sediment quality deterioration in an urban river was assessed during and after stormwater runoff and sewer overflow. Stormwater runoff bad a noticeable effect on continuous measurements of water quality in the urban river; oxygen sag and increased conductivity was a typical response. Sediment toxicity was found at sites directly exposed to urban runoff, while concentrations of copper and lead exceeded sediment quality criteria. The enzyme activity of the sediment-dwelling bacteria was found to be more sensitive with inhibition downstream and upstream of urban discharge.

During the rapid development of advanced sewage works in Sweden in the 1970's interest was primarily focused on the construction of treatment works. Practical experience from ten years of operation have shown that it may be advantageous to operate the plants in ways other than those they originally were planned for, for instance using two-stage precipitation or different techniques for recirculation of chemical and biological sludges. In order to facilitate the introduction of more efficient operational modes a joint project was started in 1980 between the Swedish Water and Waste Water Works Association (VAV) and the National Swedish Environment Protection Board (SNV). The purpose of the project, Sewage Works Evaluation Project (SWEP), is to evaluate and optimize biological-chemical treatment of municipal wastewater. Results from this project will be reported in this paper with special emphasis on the sewage works at Boras, Eskilstuna, Hässleholm, Landskrona, and Link ö ping. Within the SWEP, a lot of information is collected including physical and chemical data (analytical values from the laboratory), operational data (measurement values from the sewage works) and plant data. Methods of handling and evaluating these data will also be discussed in this paper.