1997-3

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. […]

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 […]

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 […]

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 […]

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 […]

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 […]

Lake and reservoir eutrophication is a complex process involving a variety of factors which are difficult to act upon simultaneously. The process is triggered off and perpetuated by nutriment inputs from the drainage basin. These may come into play at a later stage however, when the water body stratifies thermally in the summer, cau-sing phosphorus […]