Investigation on nutrients and heavy metal removal efficacy of seaweeds, Caulerpa taxifolia and Kappaphycus alvarezii for wastewater remediation

Abstract

Aquaculture is source of significant amount of wastes, which generally leads to general deterioration of water quality. A simple alternative to this is use of biofilters to reduce the nutrient load. Hence, the marine macroalgae Caulerpa taxifolia (biosorpent) was screened for its nutrients and heavy metal absorption capacities at various initial concentrations and contact period in laboratory conditions. Likewise, the red alga Kappaphycus alvarezii was tested for nutrient utilization besides its growth in waste water. The experiment on nutrient absorption by seaweed C. taxifolia inferred that all time intervals (6, 12, 18 and 24 hrs) maintained at different pH (4-10) in the present study showed significant amount of nutrients absorption. Of these, 24 hours biosorption at pH 7 showed the utmost removal of all the tested nutrients. The maximum absorption of zinc was recorded in pH 7 and at 24 hours with 0.5 g concentration of the seaweed being optimum under laboratory conditions. The experimental study using K.alvarezii in shrimp waste water confirmed excellent potentials of the seaweed in absorbing nutrients and thereby aiding its growth.