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Vetiver has done its job! 14 years later stable slopes, clean road drains, and now mainly native species

VETIVER SYSTEM - BUILDING COMMUNITY RESILIENCE - Managing Polluted Water

Wednesday, June 10, 2015

Some of the 100 volunteers
A major TVNI objective is to give, through VS, the ability for communities to build resilience to climate change and associated problems created by unregulated third party activities - as in this case the disposal of toxic organic chemicals that pollute community drinking water sources.  There is always a high tech solution available, but most of the time the latter are too costly and out of reach of the majority of communities.  In an earlier blog I wrote about VS latrines that are providing relief to rural folks in Haiti and the positive social health related benefits. This blog focuses on the potential application of VS to clean up illegally dumped phenols that have polluted community groundwater sources in Thailand and are of great health concern.  
A paper presented by lead researcher, T. Phenrat of Naresuan University (email: pomphenrat@gmail.com): "Laboratory-scaled Developments and Field-scaled Implementations of Using Vetiver Grass to Remediate Water and Soil Contaminated with Phenol and Other Hazardous Substances from Illegal Dumping at Nong-Nea Subdistrict, Phanom Sarakham District, Chachoengsao Province, Thailand" is well worth a careful review as the results, thus far, appear to have wide application in tropical and semi tropical countries.  There are a number of interesting facets to this research. 


First, Phenrat has shown precisely how vetiver grass has been able to reduce the level of phenol to acceptable levels (contamination was at a 250 times acceptable levels). Quote "Laboratory-scale experimental results suggested that phenol degradation by vetiver involves two phases: Phase I, phytopolymerization and phytooxidation assisted by root produced H2O2 and peroxidase (POD), followed by Phase II, a combination of Phase I with enhanced rhizomicrobial degradation. The first 360–400 hours of phenol degradation was dominated by phytopolymerization and phytooxidation. Phenol was rapidly detoxified via transformation to phenol radicals, followed by polymerization to non-toxic polyphenols or regioselective polymerization with natural organic matters prior to being precipitated as particulate polyphenols (PPP) or particulate organic matters (POM). After this first phase, phenol decreased from 500 mg/L to around 145 mg/L, while PPP and POM increased, as indicated by the increase of particulate chemical oxygen demand (COD). Synergistically, rhizomicrobial growth was ~100 fold greater on the roots of the vetiver grass than in the wastewater and participated in the microbial degradation of phenol at this lower phenol concentration, increasing the phenol degradation rate by more than 4 fold. This combination of POD-assisted phytopolymerization, phytooxidation, and rhizomicrobial degradation completely eliminated phenol in the wastewater in less than 700 hours".

Secondly, the research team with help from public volunteers and communities: (a) directly treated, with vetiver pontoons, phenol contaminated ponds (the first round of treated water was carried out over 2 months and with reduced and acceptable contaminant levels the water is to be used for crop irrigation), and (b) planted vetiver hedges (3 rows deep) on both sides (over 1 km) of a phenol polluted stream to clean up horizontal phenol flows from the stream. 

Thirdly,  the team and community planted (May 2015)  vetiver hedgerows along the boundary fence of a waste disposal area, adjoining community lands, that the owners refuse entry for onsite remediation and which is polluting adjacent community related groundwater.

Lastly, this VS technical response has allowed for a tri-party collaboration - government agencies, the public, and the affected communities  - that provides an excellent example of how such a low cost approach can be applied.

Interestingly Ngo Thi Thuy Huong of Vietnam (email: ngothithuyhuong@gmail.com) has initiated research on using VS for dioxin (a component of Agent Orange) clean up at a highly toxic site on Bien Hoh airbase. This research, which is progressing well, should also be closely followed, and is expected to have results in 2016. If the results are positive then vetiver will provide a very affordable remedial technology.

Dick Grimshaw



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