Astana Su Arnasy, Kazakhstan
Ltd ”Kurylysekspertproekt“, Kazakhstan
Alarko Contracting Group as part of Alarko Holding
September 2014 to October 2017
The artificial lake “Taldykol” was located in the south western corner of the Kazakh capital city Astana. Due to the economic and expansive growth of the city, the outskirts had reached the shore of the lake.
From 1964 to 1970 the lake was formed by raising containment dikes around the two original small lakes “Big Taldykol” and “Ulmes”. The purpose of this artificial super lake was to accommodate the wastewater from the adjacent Wastewater Treatment Plant (WWTP). From 1964 till 1973 the untreated sewage was discharged into the lake. Following the opening of the biological treatment facility in 1974, the processed sewage was released into the water body. To prevent the storage facility from overflowing, 20 million m³ of water was discharged through an emergency pipe into the surrounding lowlands every year.
This whole situation was substantially detrimental to the Taldykol environment. The lake was silting up with organic material and had a foul smell, always being close to Eutrophication.
The objective was to establish the former two small lakes “Big Taldykol” and “Ulmes” within their historic natural boundaries. The whole project consisted of 5 different phases; including the construction of a new wastewater treatment facility to stop the continuous flow into the lake. The third phase designated “Lake deepening and re-cultivation of earth works” consisted of dredging the artificial super lake and dewatering the sludge using geotextile tubes. The first tubes were filled in autumn of 2014, whereas the full-scale operation didn’t start until after the spring of 2015.
Phase three was completed in October 2017 after 5.6 million cubic metres of sludge had been dredged and dewatered in 960 Dewatering Tubes. Two different tube sizes were used, as the tubes were installed as a two-layer stack.
Approximately 78 % of the treated sediments consisted of organic deposits while the remainder mainly consisted of clay. After dewatering and consolidation, the tubes were cut open and the highly organic, dried material was used as fertilizer. Prior to the project, detailed sludge analysis and flocculation aid tests were carried out.
The Dewatering Tubes made a substantial contribution to the environmental rehabilitation of the Taldykol lake.
The Dewatering Tubes allowed for the large volumes of dredged sludge to be rapidly dewatered at comparatively low costs.
Alternative solutions such as mechanical dewatering devices would have been more costly and time-consuming options.
This project clearly illustrates the validity of the SoilTain Sludge Dewatering System.
By providing a fast and economical means of sludge dewatering, Dewatering Tubes can provide an optimal solution for state-of-the-art sludge disposal.