Qualitative evaluations about the disinfection capabilities of a water distribution network: A model study


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2014

Öğrenci: COŞKUN NADİROĞLU

Danışman: NURİ MERZİ

Özet:

“Chlorine” is one of the major disinfectants extensively used in distribution systems that neutralizes the disease-causing organisms. This model study evaluates the disinfection capabilities of a specific water distribution network N8.3 of Ankara water distribution system under various operating conditions. N8.3 supplies water, roughly to 40,000 people. The network is served by a pump station and pumping schedule is critical concerning the occurrence of minimum chlorine concentrations. Continuous “blind” pumping by a relatively small pump is found to be less critical while optimum pump scheduling making use of two “small” and one “large” pumps targeting minimum energy costs causes the lowest concentrations of chlorine. It is found that the genuine parameter which influences chlorine concentrations is “travel time” of flow from the source to the junction nodes. The network is studied in two different modes: (i) as a whole and (ii) in the form of District Metered Area’s. N8.3 is almost satisfactory based on an employed roughness parameter (CHW=130), wall reaction (kw=-0.08 m/day) and bulk coefficient of chlorine (kb=-0.10 mg/l(1-n)/day) while respecting minimum allowable chlorine concentration of 0.10 mg/l. Moreover, calibrated values of these model parameters may aggravate the results especially for critical junctions of this 20 year old network. Furthermore, seasonal variations should be evaluated for having a complete picture regarding the capabilities of N8.3 network. Ultimate solutions for avoiding perennially minimum chlorine concentrations are offered as (i) forming loops regarding dead ends, (ii) additional booster injection at the pumping station P23, (iii) cancelling problematic DMA’s.