1. Introduction & BackgroundWhat is multipond system?composed of tiny ponds and ditchesscattered

Multipond System3000 years in Chinatypically located in southern and southeastern Chinaoriginal purpose ‐‐ Irrigation retain nutrients from agricultural land reduce diffuse pollution.

Phosphorusessential element for all life formsplays a key role in eutrophicationbest management project (BMP)

a. improving agricultural management practicesb. decreasing the fertilizer inputc. controlling the transport of phosphorus

population pressure ‐‐ the need for high yields

How Multipond System control diffuse P pollution?Delay velocitySedimentationAdsorption

Study BackgroundGeographical characteristics

Liuchahe watershed, China.691.6 ha5 types: 

rice fields;   forests;village;        ponds ; nonirrigated farmland; 

Multipond system characteristics

Watershed climatePrecipitation 940 mm yr–1

Evaporation 1484.3 mm yr–1

Mean air temperature 15.5°C

Mean relative humidity 77%

Sunshine 2181 hours yr–1

Rainfall occurs during summer

Snowfall occurs 3–5 times per year

2. Study methodsSamplingEvery 15 days for the base flow

Every 4 hours during the runoff events

5 to 15 samples in each plot site

April 1 to October 31 ，1998 to 1999

Water

TP    –Total Phosphorus

DTP –

Dissolved Total   

Phosphorus

SS    –

Suspended Solids

PlantsDried at 60°C for 24 hoursWeight before and after the dryingTP was analyzed

Alternanthera philoxeroides Phragmites Communis

Soil1 kg of the upper 100 mm sediment was collected

Bottom area were measured for calculation of 

sediment accumulation

TP was analyzed

3. Result

a. Hydrological characteristics

b. Water quality

c. Phosphorus recycling

a. Hydrological characteristicsReduce the velocity effectivelyRelated to the plant coverage

b. Water qualityHigh variation of different land‐use typesWhole system much more efficient than single pond

c. Phosphorus recycling

Water

Soil

Plant

waterIrrigation 

waterDTP was the main form of phosphorus recycled

Sediments can be returned to the fields by dredgingSoil

Uptake by aquatic plants and use for livestock/poultryplant

62.1 kg of phosphorus is removed every year

4. DiscussionLoss of P is controlled primarily by interaction of phosphorus and transport factorsRetention time determines the sedimentation processWater irrigation is an effective and convenient way of recycling phosphorusThe multiple net structures of systems and the complex flow characteristics of the surface runoff is the main cause of maintaining a high phosphorus retention rate

Our Own Opinions

Our own opinions Shu & Rex

Mutipond System(MPS)MeritSignificantly delay the water‐flow process and velocityIncrease the sedimentation and retentionRemoval rate of SS is highDemeritBuffer volume(capacity) is low

? Can we combine MPS with other methods to make up the demerits?

Our own opinion Shu & Rex

Created Wetlands (CW)MeritBuffer volume(capacity) is highRemoval rate of organic pollutants and nutrients is highDemeritRemoval rate of SS is lowStuffing is  easily blocked

Our own opinion Shu & Rex

Combine two That is Multipond ―Constructed Wetland System 

(MP‐CW)

Our own opinion Shu & Rex

MP‐CW is considered as the system optimization.Exerted the advantages of  single technologyAvoid weakness with each otherRealized the complementary purpose to improve the removal efficiency of SS、COD、TN and TP. [1]

Synchronously, effectively reducing the blocking of wetlands and extending the life of the wetland. [1]

Landscaping

Our own opinion Shu & Rex

Potential danger in recycling of MPS

The multipond system is a sustainable way to control diffuse pollution and to recycle valuable plant nutrients within agricultural areas.It will be dangerous if there are rich of fatal pollutants in multipond system like heavy metals.

Our own opinion Shu & Rex

Food chain for recycling in MPS

Our own opinion Shu & Rex

How to prevent it happened?Control the source of heavy metal pollutionEnhance the strengthen of monitoring and management

Our own opinion Shu & Rex

Other Ways to Reduce Phosphorus PollutionChemical treatment 

Crystallization, Hydroxyl radical [2]

Physical treatmentSedimentation [3]

Biological treatmentBacterial: Phosphaticum; Achromobacter [4]

Spirulina [5]

Constructed Wetland

Our own opinion Shu & Rex

References 1. Wang Men, Ye Min, Yin Wei etal, Multipond Constructed Wetland

Coupled System Control the Diffuse Phosphorus Pollution, Yangtze River, 2008, 91-93

2. Yang Xianli, Bai Mindong, Han Feng, Rapid Elimination of Surface Organophosphorous Pollutants Using Hydroxyl Radical, Environmental Science, 2010,31,1670-1674

3. Fang TH, Chen JL, Huh CA, Sedimentary phosphorus species and sedimentation flux in the East China Sea, CONTINENTAL SHELF RESEARCH, 2007, 1465-1476

4. Leggett M, Gleddie S, Holloway G, Phosphate-solubilizingmicroorganisms and their use, PLANT NUTRIENT ACQUISITION -NEW PERSPECTIVE, 2001, 299-318

5. Dominguez-Bocanegra AR, Torres-Munoz JA, Carmona R, et al., Theoretical-practical study on the removal of contaminants in Los Remedios River (State of Mexico), INGENIERIA HIDRAULICA ENMEXICO, 2009, 81-91

Our own opinion Shu & Rex

Thank You

Our own opinion Shu & Rex