Use of Macrophyte Treatment Systems for Water Quality Improvement in Singapore
C.H. Sim, B.S. Quek and W.J. Lu PUB Singapore 1 3rd IWA Symposium on Lake and Reservoir Management (3 to 7 August, 2015)
Outline
• ABC waters programme • Catchment approach in water quality improvement • Examples of wetland projects • Wetland planting in reservoirs • Wetland planting in golf courses and parks • River restoration project at Kallang river Bishan park • Current research areas • Future research areas
2 Singapore’s unique urban water loop
• We have to tap on all sources of water within the water loop/cycle
• Today, Singapore collects water on 2/3 of our land area
• Each drop of rainwater falling on our catchment is important for water supply
= Singapore’s local sources of water supply 3 Introduction to ABC Waters Programme
Launched in 2006 to transform Singapore’s network of drains, canals and reservoirs into vibrant and beautiful streams, rivers and lakes.
ABC waters management strategy to apply at catchment level
A. ACTIVE New recreational spaces
B. BEAUTIFUL Integration of waters with urban landscape
C. CLEAN - Improved water quality
4 Catchment Approach in Water Quality Improvement • Placement of small treatment units in strategic locations to intercept nutrient loads – Different diffuse and point sources – Agricultural, industrial, residential areas – Stagnant water areas
Restoration of Waterways- Island wide implementation of different types of natural plant treatment units
5 ABC Waters Programme: The Blue Map with projects islandwide • Development of ABC Waters master plan and project implementation • Promote adoption by public agencies/private developers
6 Stormwater quality objectives for Singapore
• The performance targets of ABC Waters design features are directed at the protection of urban waterbodies in Singapore.
• It is desirable that new developments incorporate ABC Waters management strategies that address the impact of the developments on the water that flows into our waterways and reservoirs.
Pollutant Stormwater treatment objectives Total Suspended Solids 80% removal or less than 10 mg/L (90% of all storm events) Total Nitrogen 45% removal or less than 1.2 mg/L (90% of all storm events) Total Phosphorus 45% removal or less than 0.08 mg/L (90% of all storm events)
7 ABC waters design features Vegetated Swales
Sedimentation basins
Vegetated swales remove soil particles and convey stormwater via overland flow and mild slopes.
Bioretention Swales Sedimentation basins are ponds that provide temporary retention and a reduction of stormwater flow velocity to promote the settling of particles by gravity.
Cleansing biotope Bioretention swales are vegetated swales with temporary ponding (extended detention) to facilitate infiltration.
Bioretention Basins/ Rain gardens
Cleansing biotopes are a form of artificially constructed wetlands with recirculation. Bioretention basins are vegetated land depressions designed to detain and treat stormwater runoff. 8 Wetlands completed under Phase 1 of ABC Waters Programme
1. Alexandra Canal Wetlands – demonstration of 4 different systems 2. Grove Drive Wetlands – pilot site for surface flow wetland 3. Jurong Lake Floating Wetland 4. Pandan Floating Wetland 5. Sengkang Floating Wetland 6. Yishun Pond Floating Wetland and Marshland Lorong Halus Wetland 7. Lorong Halus Wetland – treatment wetland with subsurface flow and surface flow wetlands
Grove Drive Wetland Sengkang Floating Wetland
9 Alexandra Canal wetlands – demonstration site of wetland designs
• Located in upper reaches of the Singapore River. • 200m stretch of the open waterway decked over to construct wetlands. • Water is pumped from the canal into the wetlands for treatment by plants and filter media, then channelled to the rock scape garden and back into the canal, eventually ending up in Marina Reservoir.
Surface flow wetland Aquatic plant pond
Sedimentation pond Sub-surface flow wetland Floating Wetland Systems
Introduction of floating wetlands in reservoirs and stormwater ponds for water quality improvement
Pandan Reservoir and Jurong Lake Floating Wetlands
Sengkang Floating Wetland in Punggol Reservoir
Yishun Pond Floating Wetlands
11 Sengkang Floating Wetland
• Sengkang Floating Wetland is Singapore’s largest manmade floating wetland (2400m2). • Completed on 7 Nov 2010. • Main functions are to clean the reservoir water, improve aesthetics, and create new spaces for recreation. • Pedestrian bridge and floating boardwalk were constructed to allow the public a closer look at the wetland while minimizing disturbance to the plants and wildlife.
12 Plant selection
• There are 8 planted islands with 18,500 numbers of 18 species of wetland plants. • Chosen for their cleansing and aesthetic properties • Plants absorb nutrient and pollutants through their roots • The selected species include tall emergent such as Typha angustifolia, Canna glauca, Cyperus alternifolius, Cyperus haspan, Pandanus amaryllifolius and ground cover Bacopa monnieri, Hydrocotyle asiatica and Ipomoea pes-caprae.
13 Yishun Pond Floating Wetland and Marshland (local design) • Located beside Khoo Teck Puat Hospital, in Yishun stormwater pond. • Pond area 4.8 ha, wetland area 3,000m2, completed in Jan 2011 • Marshland around the shore softens the edges of the pond while the aquatic plants uptake nutrients in the water. • It also provides a natural habitat for fishes and birds.
Local system by Tropical Environment Pte Ltd, Singapore 14 Wetland Planting in Reservoirs and Catchments
. Competes for nutrients in the water to control the growth of algae and invasive weeds
. Improves water quality by removing contaminants such as heavy metals
. Increases the aesthetics of the area Lotus conservation site
Cattails
Spike rush Hanguana Wetland Planting in and around the Reservoir
Water banana Ludwigia adscendens beds
Kangkung Ipomoea aquatica along the bank Knotgrass Polygonum island Optimal management of submerged plants in reservoirs
Reservoirs with abundant aquatic plants have lower nutrients (TN<0.3 mg/L and chlorophyll-a <5 g/L) and high water clarity (>2.5m)
Mayaca fluviatilis Hydrilla verticillata Wetland Planting in Golf Courses
Wetland planting in golf courses is actively encouraged to reduce nutrient leaching and filter runoff from the turf.
Wetland in Sengkang riverside Park • 1 ha wetlands/ponds in a 21 ha park along Punggol Reservoir • ABC Waters Certified site • Filters rainwater naturally (runoff sedimentation basin macrophyte zone pond overflow sump reservoir)
• Acts as habitat for wildlife
Source: NParks.gov.sg 19 Wetland planting in Gardens by the Bay (GBB)
• City in a Garden Natural filter - wetlands and reed beds • Area 101 ha
• Completed in 2012 • 3 waterfront gardens
• 163,000 plants
Filter beds along dragonfly lake
Lake edge filter beds along dragonfly lake
Photo Credits: Gardens By the Bay (NParks)
20 Kallang River Ang Mo Kio Bishan Park
Singapore’s 1st large-scale river restoration project • Bishan Park: 62ha • Completed in 2012 • 3 km long naturalised river meandering through the park, flows to Marina Reservoir • Integration of river with park using floodplain concept • Combination of vegetation, natural materials such as rocks, and civil engineering techniques to stabilise the bank Kallang River Ang Mo Kio Bishan Park Cleansing biotope Improving water quality through water plants (SUTD)
• The use of water plants to reduce excessive nutrient levels at waterways. • Plants were contained within stainless steel floating platform structures 6 m X 6m, supported by simple buoyancy fittings with a slip-proof connecting platform and netting. • Water hyacinth had an average N removal rate of 125.7 mg per plant, and an average P removal rate of 7.5 mg per plant
23 In-stream wetlands for water quality enhancement in storm water canals - A field demonstration project (NUS-Deltares)
• To implement at waterways with higher nutrient inflows and with excess freeboard to prevent flooding.
• To improve water quality before catchment runoff enters the reservoirs
• Compliment implementation of upstream treatment measures, especially for treating dry weather flow.
Advanced Bioretention Systems to Minimize Nutrient Loads
• Dr. William C. Lucas (Integrated Land Management) and Prof. Margaret Greenway (Griffith University) • Project Objectives: • Determine mass load, specific nutrient retention rates and percentage of nutrients retained with advanced bioretention system, • Quantify life-cycle costs of removing these nutrients from a test site of a given area, • Evaluate the nutrient uptake potential of different tropical plant species. • Operational Application: • To testbed the effectiveness of using an advanced bioretention system to improve water quality from agricultural runoff • To evaluate different tropical plant species' ability to grow in the advanced media mix (consisting mainly of water treatment residue) and their nutrient uptake potential
25 New research areas
• Reservoir rehabilitation/remediation using macrophytes (rooted submerged and emergents) • Understanding microbial communities in water/sediment/plants for bioremediation • Using biofilter materials for nutrient removal
References 1. B.S. Quek, Q.H. He and C.H. Sim. 2014. Performance of a pilot showcase of different wetland systems in an urban setting. Water Science and Technology 71.8. pp. 1158-1164. 2. W. K. Yau, G. S. Ong, R. B. E. Shutes and C.H. Sim. 2014. Treatment of stormwater by a pilot surface flow wetland in Singapore. IWA conference on wetland systems for water pollution control, 12-16 Oct 2014, Shanghai, China 3. C.H. Sim, B.S. Quek, R.B.E. Shutes and K.H. Goh. 2013. Management and treatment of landfill leachate by a system of constructed wetlands and ponds in Singapore. Water Science and Technology 68.5. pp. 1114-1122. 4. Z. Ong, B.S. Quek and C.H. Sim. 2012. Lessons learnt from the use of vegetated floating wetlands in Singapore’s reservoirs. 13th IWA International Conference on Wetland Systems for Water Pollution Control, 25 – 29 Nov 2012, Perth, Australia 5. C.H. Sim, H.S. Eikaas, S.H. Chan & J. Gan. 2011. Nutrient removal and plant biomass of 5 wetland plant species in Singapore. Water Practice & Technology Vol 6 No 3. doi:10.2166/wpt.2011.053 6. L. H. C. Chua, S. B. K. Tan, C. H. Sim, S. Borana and M. Li. 2010. Nutrient Removal from Reservoir Inflows Using Floating Vegetation Mats in Singapore. 12th International Wetland Conference, Venice, Italy, 4-8 Oct 2010
Email: [email protected]
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