Phytofiltration of arsenic-contaminated groundwater using Pteris vittata L.: effect of plant density and nitrogen and phosphorus levels

• Published in: International journal of phytoremediation 2008-05, Vol.10 (3), p.220-233
• Main Authors: Natarajan, S, Stamps, R.H, Saha, U.K, Ma, L.Q
• Format: Article
• Language: English
• Subjects: arsenic; arsenic (As); Arsenic - chemistry; Arsenic - metabolism; Biodegradation, Environmental; Chinese brake fern; Dose-Response Relationship, Drug; Ferns; ferns and fern allies; groundwater; groundwater contamination; Groundwater pollution; harvesting; hydroponics; hyperaccumulators; Nitrogen; nitrogen (N); Nitrogen - pharmacology; Nutrient removal; nutrients; Phosphorus; phosphorus (P); Phosphorus - pharmacology; phytofiltration; phytoremediation; plant density; Plant growth; Pteris - metabolism; Pteris vittata; roots; Studies; Time Factors; Water - chemistry; Water - metabolism; Water filtration; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism
• ISSN: 1522-6514; 1549-7879
• DOI: 10.1080/15226510801997754

This field-scale hydroponic experiment investigated the effects of plant density and nutrient levels on arsenic (As) removal by the As-hyperaccumulator Pteris vittata L. (Chinese brake fern). All ferns were grown in plastic tanks containing 30 L of As-contaminated groundwater (130 μg·L −1 As) collected from South Florida. The treatments consisted of four plant densities (zero, one, two, or four plants per 30 L), two nitrogen (N) concentrations (50% or 100% of 0.25-strength Hoagland solution [HS]), and two phosphorous (P) concentrations (15% and 30% of 0.25 strength HS). While low P was more effective than high P for plant As removal initially, N levels showed little effect. At 15% P, it took 3 wk for the ferns at a plant density of four to reduce As to less than 10 μg L −1 (USEPA and WHO standard), whereas it took 4-6 wk at plant densities of one or two. For reused ferns, established plants with more extensive roots than "first-time" ferns, a low plant density of one plant/30 L was more effective, reducing As in water to less than 10 μg L −1 in 8 h. This translates to an As removal rate of 400 μg h −1 plant −1 , which is the highest rate reported to date. Arsenic-concentration in tanks with no plants as a control remained high throughout the experiment. Using more established ferns supplemented with dilute nutrients (0.25 HS with 25% N and 15% P) with optimized plant density (one plant per 30 L) reduced interplant competition and secondary contamination from nutrients, and can be recommended for phytofiltration of As-contaminated groundwater. This study demonstrated that P. vittata is effective in remediating As-contaminated groundwater to meet recommended standards.