1990-2

A large scale pilot treatment system has been used to study the effect of limiting the dissolved oxygen concentration in intermittent cycle extended aeration activated sludge (ICEAS) system on nutrient removal. The objective was to develop operating data and to establish and verify that operational conditions conductive to biological phosphorus removal can be maintained. It […]

Nitrogen reduction by denitrification in anoxic zones is increasingly used worldwide within activated sludge processes (Phosphorus removal in anaerobic zones have similar requirements). Mixing is a necessary base for good process results and involves several contradicting requirements. The design of the zones and the mixing equipment should, when possible, be done simultaneously to achieve good […]

Because of the slow growth of the nitrification bacteria at low temperature, nitrogen reduction normally requires long hydraulic retention times during winter time. Important for the nitrification process is the aerated sludge age. Factors influencing the sludge age are aerated volume, mixed liquid suspended solids concentration, organic load and sludge yield. In an existing plant […]

This paper deals with treatment of wastewater in low temperature regions of Scandinavia. The emphasis is on treatment of wastewater from small communities and recreation areas. The basic principles of chemical and biological treatment plants are described. Case studies of different types of wastewater treatment plants are presented, including treatment results and the special prerequisities […]

In sewage treatment plants several types of filters are used, most of which are originally constructed for water treatment. As a matter of fact, all filter constructions are equally suitable, when the water has been prepared in a correct way for a particular filter or, reversed, the right filter is chosen for a particular water. […]

Recent biogeochemical studies suggest that denitrification in groundwater is widespread, and that there is a close coupling between denitrification and the cycling of groundwater iron. The possibility to use this coupling for in situ treatment of iron-rich groundwater has been studied in a full-scale field test at Knislinge Waterworks, Ö. Göinge Community. Under a 50 […]

This study is concerned with nitrification in the BOD test and how to suppress it. The results show that a significant proportion of the BOD value of biologically treated municipal effluents is due to nitrification and that it can be suppressed by the addition of allylthiourea (ATU). A national survey comprising 298 samples from 35 […]