​Algae: BioHavens Remove Nutrient Loads from Eutrophic Lake - Yingri Lake, Jinan, China

Primary goal: Algae reduction.
At an urban lake in China, large reductions in chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen and total phosphorus were measured within three months after BioHaven® Floating Island floating treatment wetlands (FTWs) were installed, which met the project objectives.  The primary goal of reducing algae blooms was also achieved.

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Overview
The purpose of this floating island application was to prevent summer algae blooms by reducing the nutrient load in an urban lake.  Reductions in nutrient levels were anticipated to increase the overall health of the lake by decreasing algae growth, increasing dissolved oxygen levels and decreasing odors.  The location is Yingri Lake at Quancheng Park in Jinan, a city of seven million people in North China near the east coast.

Installation Data
Location:    Yingri Lake, Jinan, China
Parameters Studied:    COD, BOD, total nitrogen, total phosphorus, dissolved oxygen (DO)
Environment:    Lake in public park
BioHaven Size:     Total area for five islands of 7000 ft2 (660 m2); total thickness of 10 inches (25 cm)
Installation Date:    4-19-10
Flow Rate:    Non-circulating
Water Body Depth:    Average of 4 ft (1.2 m)
Water Body Area:    108,000 ft2 or 2.5 acres (10,000 m2)
% Coverage:    6.6% of lake covered by BioHavens
Species Planted:    Iris, yellow flower iris, day lily, Greek Jacob’s ladder, holly trees, ligustrum vicaryi, hosta sieboldiana, canna; some of these terrestrial plants were later replaced with aquatic plants

Funding Agency:    Gardening Bureau of Jinan City

Operational Data

Average O&M Costs (Labor, Materials):    1 hour/week; no materials
Training Required to Operate:    1-day training seminar 
Anticipated Lifespan:    At least 10 years 

Results: Please submit the request form to see before and after data
    
Percentage improvement over historic data:
COD (mg/L)    52%
BOD (mg/L)    45%
Total nitrogen (mg/L)   65%
Total phosphorus (mg/L)    89%
DO (mg/L)   50%

Yingri Lake had typically experienced a severe algae bloom every spring; however, no algae bloom was seen in 2010 after the FTW installation in April.

Conclusions
•    Large reductions in COD, BOD, total nitrogen and total phosphorus were measured within three months after FTW installation, which met the project objectives.
•    The islands are aesthetically pleasing.
•    It is unclear why dissolved oxygen concentrations decreased; however, the primary related goal of reducing algae blooms appears to have been achieved.