The change from aluminium sulphate to Kemwater FERIX-3 has led to major improvements for ZAI water treatment plant in Jordan. The plant has made important savings due to a reduction in product usage and being able to use the same equipment as before for dissolving and dosing.
The ZAI water treatment plant supplies Greater Amman with drinking water. The plant is located in the green hills just north of the capital and has undergone extensive reconstruction. Planning work started a few years ago and the extended plant will soon be ready for commissioning. The plant was designed to treat 123 000 m3/day and the plant will double the capacity to 245,000 m3/day.
The extension is a copy of the first stage plus some important improvements. The ZAI plant is situated in the village of Zai and is op-erated by the Water Authority of Jordan and LEMA - Suez Lyonnaise des Eaux and Montgomery Watson Arabtech Jardaneh LLC.
King Abdullah Canal
The raw water comes from the Yarmouk River, Mukheiba wells, Lake Tiberias and occasionally from the wadi Arab Dam. The Yarmouk catchment area includes the Golan Heights, and water from Lake Tiberias is drawn off as it flows into the Jordan River. It is then pumped into King Abdullah Canal, an open canal used primarily for irrigation, which stretches approximately 65 km from the tunnel section to the first in-take pump station. The canal functions like a big bioreactor where algae growth is high due to exposure to sunlight.
220 meters below sea level
The raw water intake at Deir Alla consists of screens, pumping stations and a 1200-mm diameter force main connected to PS1 (Pumping station 1), PS2, PS3 and PS4, and a storage (balancing) tank connected by a 1200-mm diameter force main to the ZAI water treatment plant. The four pumping stations are simi-larly equipped to handle water from 220 m below sea level to 1135 m above sea level.
After treatment at the ZAI water treatment plant the water proceeds through PS5 and a 1200-mm diameter force main onto the Daboug (terminal) reservoir, where it is transferred to a 900-mm diameter pipeline to the city network. 80% of the overall cost of each cubic meter of treated water goes on electricity, because it is pumped all the way from the lowest point on Earth.
Main issues
"Our main problem with raw water quality is during the summer season due to algae blooming and the variability of water sources and quality. During the winter season it is the high turbidity and nematode content which rise to high levels, especially on rainy days when there is a risk of flooding," says ZAI's Water & Quality Director Sa'ad Abu Hammour.
Technical data
The design of the plant is conventional and starts with a chemical injection vault, where chlorine dioxide and potassium permanganate are added for oxidation and removal of taste and odour. Then there is a regulating reservoir, followed by rapid mixers, where Kemwater FERIX-3, powdered activated carbon and cationic polymer are dosed, followed by a series of flocculators where anionic polymer is added. Then there are the sedimentation basins, followed by three-layer sand filters and a clearwell. Chlorine can be added both before and after the sand filters. From time to time a cationic polymer is used as a filtration aid.
From aluminium sulphate to Kemwater FERIX-3
"We have changed from alum to ferric sulphate because ferric sulphate works over a wider pH range and since our water has a higher pH than pH 8 we needed to use high dosages of alum. Besides the residual Al3+ is now much lower," says Process Manager/Engineer Ali Al-Ma'abreh.
"After shifting to Kemwater FERIX-3 in 1999 the dose has decreased by 35% and we now have more efficient algae re-moval. The coagulation and solids removal is improved as well as improved filter runs.
"When shifting from alum to Kemwater FERIX-3, we were able to use the same equipment for dissolving and dosing, which was a clear advantage."
Improvements
In the extension, there is a new design with perforated walls placed at the inlet and outlet of the settling basin.
- The rapid mixing has been changed from mechanical to hydraulic.
- A new main control panel has been installed in place of the existing main control. PLC link rewired to include the new main control panel.
- Addition of filter air scouring equipment.
The change from aluminium sulphate to Kemwater FERIX-3 has been very successful for Zai water treatment plant, as has the cooperation between the two companies.
