Undersøgelse af KMS-bremsens betydning i separat spildevandssystem

Abstract

Dette speciale undersøger, hvordan KMS-bremsen kan være med til at løse problemerne, der er forbundet med overgangen fra fælleskloak til separatkloak. Problematikken opstår, når de private grunde, som endnu ikke er separatkloakeret, leder fællesvand til den offentlige separate spildevandsledning. Dette vil medføre, at spildevandsledningen ved nedbør skal håndtere mere vand, end den er dimensioneret til, hvilket kan føre til gener nedstrøms i systemet. KMS-bremsen er udviklet til at forsinke vandet lokalt i systemet. Herudover er den udviklet som et enkelt og midlertidigt alternativ til de eksisterende vandbremser, da den kan monteres fra terrænniveau direkte i brønden. Undersøgelserne vil i høj grad tage udgangspunkt i et aktuelt separeringsprojekt i Nibe, Nordjylland, hvor KMS-bremsen som et forsøg er isat. Formålet med rapporten er at udarbejde data og modeller, der kan danne grundlag for at inddrage KMS-bremsen allerede i planlægningsfasen fremover. I rapporten vil der blive udarbejdet analytiske udtryk og CFD-modeller, som blandt andet kan beskrive relationen mellem vandstand og vandføring gennem bremsen under givne forudsætninger. De udviklede modeller sammenholdes med resultater fra udførte laboratorieforsøg. Endelig implementeres de udviklede QH-relationer i en hydraulisk model i MIKE+ med henblik på at undersøge KMS-bremsens funktion med udgangspunkt i systemet i Nibe.

This master's thesis examines how to prevent the challenges associated with the process going from a combined sewer system to a separated sewer system. The challenges occur because private citizens have to separate the sewer on their own properties. This means there will be a period where diluted wastewater from the properties will be directed to the separated wastewater system. However, the separated wastewater system is not designed to handle that amount of water, which can lead to overloading of the pipes during rain events. When the pipes become fully loaded, it can force the water to flow back. Additionally, it can cause issues with the accumulated gases from the wastewater, which can create over- or under-pressure in the system. Pressure or suction due to changes in air transport can further cause problems with odors through the water traps in the installations. In order to avoid these capacity problems connected to the transition phase, Kim Skals from Envidan Aalborg has developed the KMS-flow regulator. The flow regulator is a simpler and more economical alternative to existing flow regulators, taking into account that the transition phase is only temporary. The purpose of this report is to generate data and models for the KMS-flow regulator to enable its inclusion in the planning stage of a new sewer system. The first part of the thesis will go through the legislation and theories associated with the process of developing new sewer systems. This is followed by an introduction to the KMS-flow regulator. In the second part of the report, the case study for the project will be introduced, which will be used as a reference for the created models presented in the report. The case study is located in Nibe, Northern Jutland, and is currently transitioning from a combined sewer system to a separated sewer system. Furthermore, various models will be developed to describe the effects of the KMS-flow regulator. To estimate the flow through the regulator, an analytical expression will be constructed. Computational Fluid Dynamics (CFD) will be used to create a model that can simulate the water flowing through the system. By using this model, potential improvements to the KMS-flow regulator can be tested. The models and the analytical expression will be compared to results from tests conducted in the laboratory. Finally, the relationship between the water level in the well at the inlet and the simultaneous flow through the regulator will be implemented in a hydraulic model constructed in MIKE+. This will demonstrate the impact of the KMS-flow regulator as part of a system by comparing the water level in the downstream part of the system. Results and assumptions made throughout the report will be discussed in the last part of the master's thesis.

A master thesis from Aalborg University

Undersøgelse af KMS-bremsens betydning i separat spildevandssystem

[Investigation of the impact of the KMS-flow regulator in a separate sewer system]