Alla artiklar

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. […]

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 […]

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 […]

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 […]

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 […]

Sulphide toxicity due to high concentrations of sulphurous compounds in some industrial wastewaters results in difficulties when using the favourable anaerobic treatment; it even makes anaerobic treatment impossible. Today, several methods are available for control of sulphide toxicity: heavy metal sulphide precipitation, addition of alkali to raise pH and thereby convert the toxic H2S to […]

Open black top pavement has advantages over usual black top in view of economics, accidental statistic and environmental factors. Noticed about the environmental advantages are lower load on waste water filtration plants, lowered risk for spillway overflow, less pollution to recipients, lowered noice levels for traffic and sustained ground water balance. The risk for clugging […]

Lakes have an important impact on element mass transport. The reduced velocity results in an increasing sedimentation and chemical and biological processes have time to influence the transport. Hydrochemical models can be helpful in the study of the importance of different processes. In this study we present simulated concentrations and mass transport of zinc, copper […]

A high resolution hydrodynamic model is used to estimate fluxes between boxes in a coarse compartment model. The latter model may include complex biogeochemical processes, here exemplified by dispersion of radionuclides released from a nuclear power plant. The water recipient – Öregrund Grepen – is assumed non-stratified and the circulation to be mainly winddriven. The […]

A city is an alien element in natural ecological systems. All anthropogenic systems become monocultures with open material and energy systems. Overexploitation of natural resources (raw materials, water), or enrichment of residuals (pollutions) are the consequences. Today it is clear that urban areas must be kept in some kind of equilibrium which is acceptable for […]