OVERVIEW:
The Phan Rang – Thap Cham WTP, with a designed capacity of 40,000 m3/day, is owned by the Ninh Thuan Water Supply Joint Stock Company. It was constructed in 2006 with funding from the Asian Development Bank (ADB). This plant is the largest water plant serving the clean water needs of residents and the development of industry and tourism in Phan Rang – Thap Cham City, Ninh Thuan Province.
The Phan Rang – Thap Cham WTP utilizes surface water extracted from the Cai River, located approximately 1,000 meters from it. Although the water quality of the Cai River is generally good and stable, its turbidity can be relatively high during the rainy season.
Between 2005 and 2008, the demand for clean water in Phan Rang increased significantly due to the booming tourism and socio-economic development in the province. Consequently, the plant had to operate beyond its designed capacity but still could not meet the demand. Ninh Thuan Water Supply Company diligently researched and considered various models. Finally, they decided to choose a process improvement solution to increase capacity.
In 2012, Ninh Thuan implemented a technology solution using TK Plate® settlers, TK Collector® systems, and agitators as a technological solution to increase the capacity of the Phan Rang – Thap Cham Water Plant from 40,000 m3/day to 96,000 m3/day, a solution that was suitable for their limited financial resources.
CASE STUDY
Before the capacity enhancement, the Phan Rang – Thap Cham Water Plant had a designed capacity of 40,000 m3/day and was operating at nearly 50,000 m3/day. The basic technological process was as follows:
Equalization Tank -> Flocculation -> Horizontal Sedimentation -> Rapid Filtration -> Reservior
The raw water was extracted from the Lam River with the following basic quality parameters:
Turbidity: 15 – 250 NTU (can reach > 1000 NTU during the rainy season).
pH: 7.0 – 7.3.
The chemicals used for treatment included:
PAC: used for flocculation.
Vôi: used for pH adjustment.
Chlorine: used for disinfection.
Flocculation tanks: Utilized hydraulic mixing principles with tapered baffles to reduce velocity, facilitating larger floc formation. Hydraulic retention time was maintained at approximately 30 minutes. To increase capacity, water volume was augmented, and water levels were lowered to prevent overflow.
The sedimentation tanks: Employed 4 conventional horizontal sedimentation tanks, each with dimensions of 30 m x 8 m. Settled water was collected at a common outlet channel. Due to overloading, post-sedimentation turbidity often exceeded 5 NTU.
Filtration tanks: The settled water was distributed to 8 filtration tanks using a mono-layer rapid gravity method and the clean water was collected via nozzles. Operation was controlled by a PLC via an electric valve system. Each tank measured 4 m x 8 m, with filtration rates ranging from 6.5-8.5 m3/m2.h, meeting quality standards.
Achievements with TK+ Technology Solutions:
TK+ upgraded the existing flocculation tank by applying hydraulic principles, installing flocculation agitators and hydraulic baffles (perforated wall) at the sedimentation tank inlet. This created a buffer zone extending the reaction time with reduced flow velocity, fostering the formation of larger flocs and improving flocculation efficiency.
In the sedimentation zone, 8 TK Plate® settling modules were installed, each with a nominal design capacity of 3,200 m3/day/module. The treatment capacity reached 25,600 m3/day, totaling 102,400 m3/day.
All sludge produced during treatment was collected and removed using a submerged TK Sludge Collector system, covering the entire sedimentation zone.
Post-overhaul, water quality remained stable, with turbidity fluctuating between 0.5 – 1.5 NTU. PAC usage decreased by over 30%, and the filtration cycle increased to over 96 hours, with a capacity of up to 96,000 m3/day.
Ninh Thuan Water Supply Joint Stock Company is very satisfied with this investment. They express their gratitude to TK Plate® and TK Collector® technologies for delivering unexpected success.