Alla artiklar

Segmented flow extraction has been applied to studies of the n-octanol/water partition of aquatic humus. This material is a heterogeneous mixture of compounds many of which have surfactant properties complicating the studies. The segmented flow extraction method is proved to be a simple and useful tool for screening the lipophilicity of humus thereby aiding in […]

Activated sludge is a complex ecosystem consisting of bacteria, protozoa, yeast and virus. Because bacteria are such a large and important component of activated sludge floes, bacterial adhesion is a crucial mechanism of the flocculation. We have studied how electrostatical interactions influence floe stability and sedimentation in water with different ionic composition. Changes in floe […]

The paper describes the use of wooden pipes, particularly drilled pine logs, as rural water conduits in Finland. The first documented case of such a system serving a single house is from Ilmajoki, Ostrobothnia from 1865. Later on, the system was expanded and the first joint system was completed in 1872. The latter scheme was […]

The objectives of this study were to investigate the possible effects of freeze/thaw-drying and drying as sludge dewatering methods on the organic matter, nitrogen, and phosphorus content in the sludge. The research work was carried out on three different levels. The effect of natural sludge dewatering on the overall status of the sludge was mainly […]

Anaerobic biological treatment has proven to be a successful method for reducing Cr(VI) in a leachate from Vargön Alloys AB. Influent chromium concentrations ranged from 10-120 mg/L and satisfactory reduction was achieved in both laboratory and pilot plant studies, as long as sufficient amounts of electron donor were added. Glucose, acetic acid and sulfite evaporator […]

Sludge bulking has been a problem ever since the activated sludge process was introduced for wastewater treatment. The problems were accentuated when low-loaded processes for nitrogen removal were introduced. Sludge bulking may appear in many forms and be caused by many different factors. Common in low-loaded processes are bulking caused by mass-appearance of filamentous bacteria. […]

The hardness of water, or rather the concentration of calcium and the alkalinity, has throughout the years been described with great diversity and imagination. The aim has always been to simplify the actual, nuanced and complex chemistry in question. The many assumptions and terms for these simplifications have in course of time become vague or […]

The Swedish company, VYRMETODER AB has developed a means of treating water in an artificial aquifer according to the VYREDOX method. The method is based on degassing and aeration of raw water which is then infiltrated into the artificial aquifer. The article informs about three VYRAKVI plants installed in the mountainous region in the north […]

There are wastewater treatment plants in Uppsala municipality with both high and low copper concentrations in the sludge, this is somewhat surprising as the raw water (groundwater) often is pumped up from the same esker (gravel ridge or glacial origin), the chemical composition or the water is expected to generate strong copper corrosion, as the […]

Hydraulic transients occur at rapid flow changes in pressurized water conveying pipelines. Normally such transients (waterhammer) are considered to be a problem as they might damage the pipeline due to strong pressure peaks, subatmospheric pressures or fatigue. However, normally occurring hydraulic transients have also a potential to be utilized in an advantageous manner. ’The idea […]