Based on overall mass balances for water, total nitrogen and organic carbon in the VEAS WWTP in 1997, alternative strategies for nitrogen removal are discussed based on cost optimisation. Marginal costs for biological removal are compared with total costs for side stream treatment by ammonia stripping. If the plant has sufficient capacity to meet the effluent requirements with biological removal alone, this study demonstrates that the price of methanol determines whether or not invetment in ammonia stripping still is a cost efficient solution.
Water retention times less than 3 h from inlet to outlet were necessary to meet new effluent requirements without extending the footprint of the existing plant. Nitrogen removal was required at the existing, high loaded, direct precipitation plant and space was not readily available. The staff at the VEAS WWTP took on the task to design a new process at their own risk. Selected solutions and ups and downs in the water treatment during the past 10 years of operations and further developments are presented in this paper. Always asking for well-proven solutions might make life easy. The intent of this paper is to encourage some of our colleagues to be more daring in their approach to new challenges. However, expect sleepless nights in order to solve the unexpected problems along the way.
In order to obtain compact plants and to assure a greater treatment reliability, fixed film reactors have been developed. This biofiltration has been applied and proved for over a decade for carbon removal. Today, new applications appear in nitrogen and phosphate removals, which are able to respond to the upgrading of aging waste water treatment plants. Full scale plant results are presented in nitrification. The use of two stages of biofilm reactors (C + N) permits high effluent quality. Chemical phosphate removal and denitrification results obtained on pilot tests are also discussed. Some plants are now been built with such processes.
The VEAS concept, in Oslo, which includes four steps of fixed film reactors is discussed as an example of this present upgrading tendency.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.