Research

Water Hyacinth (Eichhornia crassipes) Research and Application

1. Project Achievements and Progress

Phytoremediation of eutrophic waters using water hyacinth (Eichhornia crassipes (Mart.) Solm-Laub) started in 2006, when the blue-green algae was blooming in Taihu Lake, Jiangsu Province, China. System analysis showed that the overload of nitrogen and phosphorus was the main cause of the problem. Among the would-be solutions, there were considerations of ecological safety, cost, scale, efficiency, short and long term effectiveness, technical feasibilities, and so on. It seemed that there were no good solutions, especially having problem on ecological safety if selecting water hyacinth as treatment agent, on efficiency if selecting other macrophytes, on cost, scale, short and long term effectiveness if selecting non-macrophyte remediation methods and on technical feasibilities if selecting other new technologies, such as nanotechnology treatment. According to Prof. Shao-Hua Yan's theory of nutritional cycle in eutrophic waters and a model interpretation, the best solution was to use macrophytes to permanently remove nutrients from lakes. However, literature suggested that there were serious side effects associated with bioremediation using water hyacinth.

Pilot project was launched to study at the ecosystem level to investigate and to solve the real time problems range from effects on aquatic ecosystems, confined growth, biomass collection, harvest and transportation, post-harvest process, biomass utilization as bio-resources, effects on social and economical development, and cost-benefit analysis of the project. Establishing theory of nutritional dynamics of eutrophic waters and focusing to systematically solve technical problems at each step, this pilot project has been executed for years and showed very good results and a bright future.

Confined growth: The inventions of confined growth mainly solved problems of ecological safety by preventing the formation of large scale continuous macrophyte mat to improve dissolved oxygen supply for aquatic lives, by preventing this invading species at large and by preventing the blockage of water ways for transportation of fisheries, commercial goods and passengers.

Biomass collection: The technologies of biomass collection provided solutions for ecological safety, preparation for cost reduced harvesting by efficiently collecting and transport more than hundred tons of biomass of water hyacinth over more than tens of kilometers on water surface.

Harvest and transportation: The patents of this key technology ensured successful bioremediation using water hyacinth by completely and cost-effectively removing million tons of water hyacinth biomass from the water and hence removed plant nutrients from the aquatic ecosystem to leave a cleaner water behind.

Post-harvest process: On large scale application of bioremediation over hundreds of square kilometers of lakes and reservoirs, such as Taihu Lake and Dianchi Lake, water hyacinth biomass may be of over million tons per year. To efficiently and economically process the biomass is critical since delayed processing means the pollut source would be moved from water to land, and by rotting and wash-away, the pollutants would easily return to water. The patents of post-harvest make sure the biomass of water hyacinth can be timely and efficiently processed to leave a clean land and water for the catchment.

Biomass utilization as bio-resources: Over million tons of fresh biomass per year will require considerable amount of resource for costly landfill operation. This is unacceptable option, especially in developing countries as land is always scarce and valuable. The technologies of biomass utilization turned costly landfill operation to valuable production process to produce energy, fertilizers and animal feeds, which provide valuable resources for local economic development, and to compensate for the cost of bioremediation execution.

Effects on social and economical development: The assessment of the pilot project showed that there were upgraded ecosystem services, better fisheries, clean water resource, better supplying of energy, fertilizers for crops and feeds for animal husbandry.

Cost-benefit analysis:

Cost at different steps:

Cost for harvest (fresh weight, USD3.00/ton), Cost for dehydrate (fresh weight, USD2.10/ton), cost for bio-energy (fresh weight, USD0.8/ton), cost for organic fertilizers (fresh weight, USD0.93/ton), cost for feeds (fresh weight, USD4.5/ton).

Cost for Products: Liquid fuel (USD540.00/ton), Organic fertilizers (USD142.00/ton), Green feed at water content of 30% (USD137.00/ton)

 

2. Project Introduction Video

Confined Growth of E. crassipes and Its Resources Utilization

3. Project Presentation

  1. Project Introduction;
  2. Water Quality Restoration of Dianchi Lake Using Water Hyacinth;
  3. N and P Removal from Dianchi;
  4. Denitrification;

4. Project History and Publications

Eichhornia crassipes (Mart.) Solm-Laub, common names of water hyacinth, waterhyacinth and water-hyacinth frequently seen in literature, was first recorded in 1816 by a German botanist C.F.P. von Martius in Brazil. It was later classified into Monocotyledoneae (class), Commelinales (order), Pontederiaceae (Family), Eichhornia (Genus), crassipes (Species). This species is known as the largest free floating, fastest growing and serious ecological problem making macrophyte in tropic and subtropic waters, but not in brackish waters. For many decades, people failed to keep this species out of warm aquatic environment.

The Pollution Control, Water Management and Resources Utilization research group in Jiangsu Academy of Agricultural Sciences has changed the negative Keep-It-Out strategies to the positive System Development and Technology Integration strategies through naturally confining, mechanically harvesting and safely utilizing this species to solve serious ecological problems, to produce useful bio-energy and to remediate eutrophic waters at the same time.

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