1991-3

Sludge accumulation techniques in pond systems for wastewater treatment, particularly those using chemical precipitation, were reviewed. The chemical sludge at Bruksvallarna treatment plant, a ten year old chemical precipitation pond using alum (AVR), was investigated with respect to volume and content of total solids and its volatile fraction. The volume of the primary sludge was […]

The stability of an accumulated lime sludge after termination of lime addition was investigated at the Funäsdalen wastewater pond system in Sweden. The lime addition was terminated for 53 h and then resumed. pH decreased from approximately 12.0 to a maximum of 7.0 at the inlet and 10.0 at the outlet end of the ponds. […]

The present eutrophic status of Lake Eastern Ringsjön in Southern Sweden can be predicted using a simple mass balance model based on 2 trophic levels. The system was modelled using growth and mortality kinetics for fish and plankton, and sediment-fish-water interactions. The model predicts the transition to eutrophic lake from a stable oligotrophic state in […]

A program to chart the sources for undesirable contaminants in the influent water to Ryaverket was started in 1988. Stage one was a study of domestic sewage. Two residential areas in Gothenburg were chosen and sewage water was collected on four occasions during the year, as 24 h flow proportional samples. These were analysed together […]

Aspects of the selection of filters for the determination of suspended solids in effluents and natural waters are discussed. Different brands of glass fibre filters and polycarbonate filters are compared. No single filter can be standardized for the determination of suspended solids. The choice of filter depends on the measurement in question and on the […]

Water resources management in Germany is based on river basin related planning and discharge fees respectively. Large amounts of data are processed in the planning, that is describing and analyzing, emphasizing on solving conflicts between water users (including the natural ecosystem). Management is more connected with the fees that are taken out mainly on the […]

The process is here called “Simultaneous Denitrification” though intensive treatment with activated sludge is concerned and biological removal of both nitrogen and phosphorus is obtained. However, nowadays nitrogen removal is more interesting, as phosphorus removal is possible by several methods. The process has no specific aeration or anoxic zones. Nitrification is intensive, primarily because of […]

This article discusses the main issues of the Gouvernment’s latest proposition called “a satisfactory environment for living”. Discharge of nitrogen from antropogenic sources, especially from sewage treatment plants on the coast, is discussed. The National Swedish Environmental Protection Board, SNV, has claimed that 70 major sewage plants ought to be extended with efficient nitrogen removal […]

Nitrogen removal by biological denitrification is a well-known process. Several processes in full scale are operating in Scandinavia. The process alternatives are described on the basis of biomass composition, process lay-out, and special contractor design. The systems described includes biological filters, seperate sludge systems, and combined sludge systems. Combined sludge is the most common system […]

At GRYAAB’s wastewater treatment plant, Ryaverket, in Gothenburg, pilot plant investigations are being performed for evaluating technologies which can be used to meet anticipated demands for 50 % nitrogen removal. Two alternatives are being investigated. One alternative uses pre-denitrifiction in the activated sludge process. Preliminary results show that this is a functional but expensive alternative […]