HEAVY METAL UPTAKE BY GREEN ALGAE DURING REMOVAL OF NUTRIENTS FROM NEW YORK CITY WASTE WATER

Heavy metals such as lead, cadmium, molybdenum, arsenic and chromium, when dissolved in water can be very hazardous. To prevent or to reduce the effects of bio-magnification and bioaccumulation it is important to remove heavy metals from the water source. For the past few decades, research is being done to develop methods for removing heavy metals and nutrients from the urban waste water prior to discharge to river or bay. Recently, an eco-engineering technique is being applied in one of the biggest New York City waste water treatment plant in Jamaica to remove nutrients from primary treated wastewater by growing green algae. Studies have proven algae to be highly effective as well as reliable and predictable. In this experiment, grown algae body mass, collected from treatment plant of Jamaica Bay were studied to evaluate the uptake of heavy metals by algae in addition to nutrients. This is very important since DEP plans to produce bio-fuel from this algae biomass. The solid mass of green algae was obtained by removing more than 80% of water in their body mass. A convection oven was used to dry the algae until it reaches the constant weight. The mass was grinded to the powder and packed in XRF sample cups with thin- Mylar film sample support windows for x-ray spectrochemical analysis. A set of reference materials and internal standards were run before and after a batch run to maintain the QA and QC of the entire run. DEP grown green algae consistently showed the high level of heavy metals including Pb, Cd, Cu, Zn, Ag, Cr, V, Sb and Ni compare to green algae collected from a contaminated pond in Jamaica (Goose pond). The results suggest that the municipal waste water contains high level of heavy metals. A laboratory experiment is under way to grow same algae species in nutrient rich artificial fresh water spiked with high concentration of heavy metals including Pb, Cd, Cu, Zn, Cr and As. The bioaccumulation capacity of algae will be evaluated in the controlled environment. The outcome of this study may be implemented in countries facing major health issues associated with heavy metal contamination. In addition to XRF measurement, heavy metals would be determined using Differential Pulse Cathodic Stripping Voltametry (DPCSV ) and Inductively coupled plasma optical emission spectrometry (ICPOES) followed by the sequential extraction.