1999-1

The Swedish urban water systems have been in use and under continuous development for more than a century. The urban water systems of today fulfil to a high degree basic requiremenrs concerning safety, hygiene and protection of the environmeni. For the past years, however, the systems have been criticised from the viewpoint of sustainability. The […]

Wetland creation costs and their determinants are studied by an analysis of detailed dara on wedand creation programmes for causing nitrogen reducdon in two drainage basins in the agricultural district of SW Scania, southernmost Sweden. Estimated cost equations illustrate the importance of excavarion efforts for obtaining good predicrions of creation costs. An analysis of the […]

Pressure recordings during transient conditions can be utilized for leak detection purposes on single pipes. This method has been described in a research project report CVA-Forsk, 1997) by the authors. In this case study a pressure main, situated in a lake and subjected to a leak, was examined by using pressure recordings. Two possible leak […]

Expansion for nitrogen reduction on Kalmar wastewater Treatment Plant (KARV) was realized with 2 sequencing batch reactors (SBR) for separate treatment of filtrate water. Online measuring instrumems were installed to make control of the SBR-process easier. The waterlevel and DO-meters are used for automatic operation control, whereas information on sludge content, pH, redox-pontential, ammonium and […]

Models and modeling require management of the inherent complexity. Simplicity in models and modeling is a positive characteristic. Models and modeling possess no intrinsic value. Their value may be assessed only relative to an objective or a problem to be solved.

Mesophilic and thermophilic digestion of primary and activated sludge was investigated in lab scale reactors. Mixed primary and activated sludge was digested in one experiment and activated sludge was digesred alone in another. The same gas yield, COD and dry solids reducrion was obtained with both mesophilic and thermophilic digestion. However, more dissolved COD was […]