THE PROBLEM: Sludge formation, algae blooms, foul gases, increased nutrient input — The Yanshan Garden public park in the Chinese city of Taicang invites residents and tourists alike to stroll through an area filled with views that present a harmonious composition of nature and architecture. The jewel in the park’s crown would ordinarily be the centrally located lake – that is, if the water wasn’t incredibly cloudy. Over the course of ten years, leaching, an excessive population of fish and algae growth have all led to a deterioration in water quality and a considerable development of sludge. Operators sought a cost-effective solution for treating the water that, insofar as possible, could be applied without closing the park. During their research, the operators came across Oase Professional and were able to receive the proper help from the Oase Water Technology experts.

Project Overview:

Background:
The park operators did not want to merely offer those seeking somewhere to rest and relax a place to explore nature undisturbed and free from cloudy water and foul smells. They also needed to meet the strict state requirements for surface water in China – specifically, quality level V. One of the restrictions imposed by this quality level is a maximum quantity of substances such as ammonia, phosphate and nitrogen. Quality level V water must also feature a visibility depth of at least 80 cm (31.50 in), in its original condition. The 2.5 hectare (6.18 acre) lake was a long way from this.

The Solution and Treatment:
Fast treatment against foul smell was a must and water analysis pointed towards treatment using SchlixX. The product binds phosphates into an insoluble and environmentally neutral mineral called apatite, thereby reducing the supply of nutrients. It also releases oxygen, which stimulates the microorganisms in the water to break down organic materials.

To provide targeted treatment for individual areas, the lake was divided into five sections from A to E. The first attempted treatment began in March 2021, but had to be interrupted due to simultaneous restoration work on the bank of the lake. This restoration work caused a considerable amount of additional nutrient input, which temporarily worsened the water quality even further and led to an algae bloom in February 2022. However, this unfortunate course of events did not prevent the Oase Professional experts from continuing to treat the water, this time, in a more appropriate setting: Only area E of the lake would now be treated to combat algae growth by phosphate binding and to remove the sludge using SchlixX, since this segment is only connected to the rest of the lake by a five meter (5.47 yard) wide channel and therefore offers a stable working environment.

Successes and Results:
Following the initial setback, significant improvement could be seen just one month after treating the lake in May 2022: The water in segment E was so clear that fish and even stones were visible at the bottom of the lake – a major success for the entire team and a visual delight for park visitors. Obviously SchlixX had done a lot of work.

The contrast with the other, as yet untreated areas of the lake was obvious. These areas had developed a thicker layer of sludge, were plagued by algae growth and had become even cloudier than before. The result in the treated area was so convincing that the operators made a plan to similarly initiate treatment of the remaining four areas once the renovation of the bank is complete.