There are heavy metals in wastewater of many industries such as the mining, petrochemical, oil refining, paper, pharmaceutical industry, paint and plastic products industries. Entering these metals into water resources cause to add these metals to the food chain. This action was done through the absorption of these metals by microorganisms and causes a lot of problems for humans. To remove heavy metals, there are various physical, chemical and biological methods. From these methods researchers pay attention to the biosorption process Because of this method with using of a series less valuable materials are able to remove many heavy metals. Biosorption is the physical and chemical absorption of heavy metals by living and non-living microorganisms (bacteria, fungi, algae) and other organic object such as (rice bran, fruit skins, leaves and skin of trees, etc). At this thesis, the waste of Goldar and two brown algae, Nizamuddin zanardini and marginutum were used for removal of heavy metals such as lead, cadmium and chromium. The algal species, Nizamuddin zanardini and marginutum, were acquired from Oman Sea coast of Chabahar and Otostegia persica, known as goldar, is an endemic plant that can be found in its natural habitat in Kerman province in Iran. The standard stock solutions of 20 mg/L of Pb(II), Cd(II) and Cr(VI) were prepared by dissolving appropriate amount of Pb(NO3)2 , Cd(SO4).8H2O, K2(Cr2O7) in distillated water. The alga was washed extensively with distilled water to remove dust and other particles. The clean biomass was sundried for 24 h, and then in the oven at 50 °C for 24 h Absorbents were used initially as raw form and then modified with 4-phenyl-3-thiosemicarbazide and finally with sodium alginate polymer for removal three metals. For these absorbents, three models (Langmuir, Freundlich and Temkin) were evaluated and the result shows a good conformity between the experimental data and Langmuir isotherm. Langmuir isotherm shows a homogenous absorption on the homogenous surface and theoretical qm for absorbent are acceptable with the experimental qm. To investigate the kinetics of the process, the pseudo- second order model and intra particle diffusion was used. Presenting this model (intra particle diffusion) was done for investigating of multistage absorption. This absorption is as 2, 3 stages. In this model, diagrams of sorption capacity inclusive sorption on the surface of biosorbent (linear with high slopes), penetrate the pores (average linear slope) and penetration in the biosorbent structure (linear with very little slope) were considered. Ho’s pseudo – second order model conform for most raw and modified absorbents. The most important effective parameters into absorption process such as pH, initial concentration and the amount of biomass was investigated in this project. The pH of the solutions was adjusted to a favorite value using 0.1 M NaOH and 0.1 M HCl. The result shows that optimum pH for maximum removal of aqueous solution are 5 to 6 for cadmium and lead, 3 to 4 for chromium. Another important effect observed in this project was increased absorption capacity with initial concentration and the increase of absorption percentage with increase of biomass concentration. Keywords : waste Goldar, Zanardini, Marginutum, Heavy metals, Isotherms, Kinetics.