Publications by authors named "H Helness"

A novel approach for resource recovery includes forward osmosis (FO) as a concentration step in municipal wastewater treatment. The current study investigates different pre-treatment strategies including biological treatment with a moving-bed bioreactor (MBBR) at different loading rates and particle removal by filtration and sedimentation. Membrane performance and recovery potential for energy and nutrients were investigated in laboratory-scale FO experiments in batch mode using pre-treated municipal wastewater as feed and 35 g/L NaCl as a draw solution.

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The paper discusses how citizen science within an ecosystem services (ESS) framework may enhance evaluation of de-centralized water solutions. In a demonstration case in Oslo, citizens were engaged in long-term monitoring and evaluation of two solutions for treatment of combined sewer overflows. The citizens participated in the design of the study, systematic observations, and final evaluation, via interviews and workshops.

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Combined sewer overflows (CSOs) pollute receiving waters and have a negative impact on ecosystem services. In urban areas rehabilitation of the sewer system to avoid CSOs is associated with high investment costs. Furthermore, not all CSOs can be closed due to the need for hydraulic reliability of the system.

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The goal of this research work was to find a sorbent able to selectively retain the harmful dissolved compounds in the wastewaters from offshore platform operation but not the carboxylic acids and to study the effects of the most important parameters on the sorption process. BTX compounds (benzene, toluene and p-xylene) and acetic acid were chosen as the representatives of the harmful compounds and carboxylic acids groups respectively since they are found in the highest concentrations. An organically modified clay was determined to be the most suitable sorbent, where performance was evaluated at different values of pH (3, 5 and 8), acetic acid concentration (0, 160 and 320 mg/l), salinity (0, 35 and 70 g/l) and temperature (20, 40 and 60 degrees C).

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Many cities around the world are looking for compact wastewater treatment alternatives since space for treatment plants is becoming scarce. In this paper development of a new compact, high-rate treatment concept with results from experiments in lab-scale and pilot-scale are presented. The idea behind the treatment concept is that coagulation/floc separation may be used to separate suspended and colloidal matter (resulting in > 70% organic matter removal in normal wastewater) while a high-rate biofilm process (based on Moving Bed biofilm reactors) may be used for removing low molecular weight, easily biodegradable, soluble organic matter.

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