Ecological Engineering 106 (2017) 101–108 Contents lists available at ScienceDirect Ecological Engineering journal homepage: www.elsevier.com/locate/ecoleng Biosorption of heavy metal ions by chemically modified biomass of coastal seaweed community: Studies on phycoremediation system modeling and design Fatih Deniz a,∗ , Abdulkerim Karabulut b a Department of Environmental Engineering, Faculty of Engineering and Architecture, Sinop University, 57000 Sinop, Turkey b Department of Electrical and Electronics Engineering, Faculty of Engineering and Architecture, Sinop University, 57000 Sinop, Turkey a r t i c l e i n f o Article history: Received 23 March 2017 Received in revised form 16 May 2017 Accepted 17 May 2017 Keywords: Heavy metals Seaweeds Biosorption Phycoremediation a b s t r a c t Biosorption of heavy metals by seaweeds (marine macroalgae) is a potential environmental biotechnology technique for biotreatment of industrial effluents. However, the co-application of biomasses of different seaweeds for bioremoval of these inorganic pollutants from aqueous phase is very limited. In this study, for the first time, a coastal seaweed community composed of Chaetomorpha sp., Polysiphonia sp., Ulva sp. and Cystoseira sp. species harvested from the north coast of Turkey was first treated with sodium hydrox- ide and then used as natural biosorbent material for the bioremediation of zinc-containing synthetic wastewater. Batch biosorption experiments were performed to optimize the conditions of environmen- tal parameters (pH, biosorbent quantity, heavy metal concentration and contact time). The biosorption capacity of biosorbent for zinc ions was highly affected by the operating conditions. Kinetic studies showed that the biosorption process was multistep, fast and diffusion controlled. The pseudo-second- order rate model well described the biosorption kinetics. The equilibrium data of zinc biosorption fitted best with Sips isotherm model and the maximum biosorption capacity of biosorbent from this model was calculated as 115.198 mg g −1 . Thermodynamic parameters indicated that the biosorption process was physical and spontaneous. Besides, a single-stage batch biotreatment system was designed and the kinetic performance of this biosorption system was evaluated. The obtained results revealed that the pre- pared composite biosorbent could be used as efficient novel biosorbent for zinc removal from aqueous effluents. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Heavy metal pollution is a serious global environmental prob- lem. These inorganic pollutants are often released into water bodies as a result of various anthropogenic activities. In particu- lar, intensive technological and industrial developments have led to excessive use of heavy metal ions and thus increasing water pol- lution. Heavy metals are often reported to have harmful effects to human and other organisms due to their high toxicity and cumula- tive effects. Zinc is one of the most common heavy metals present in industrial effluents. It is an essential element for humans, plants and other living beings. The deficiency of zinc in human body leads to several adverse effects such as taste abnormality, diar- rhea, lethargy, delayed healing of wounds and growth retardation ∗ Corresponding author. E-mail address: f deniz@outlook.com (F. Deniz). (Ng et al., 2016). Although it is important for human health, excess zinc is toxic for humans and its main symptoms are nausea, dizzi- ness, electrolyte imbalance and muscle stiffness (Afroze et al., 2016; Girardi et al., 2014). Seaweeds (marine macroalgae) are important natural biomass resources. They are available in abundance, renewable, non-toxic and low in cost. Marine macroalgae have various bioactive com- pounds such as polysaccharides, proteins, lipids, polyphenols, carotenoids and vitamins. These phycochemicals have different functional groups including carboxyl, hydroxyl, phosphate and amine that can bind the heavy metals (Areco and dos Santos Afonso, 2010; Sanjeewa et al., 2016). Biosorption is one of the most promis- ing remediation technologies for aquatic areas polluted with heavy metal ions (Gupta et al., 2015). The major advantages of biosorp- tion using the biomass of seaweeds for wastewater treatment are less investment in terms of both initial and operational cost, simple design, easy operation and no effect of toxic substances. http://dx.doi.org/10.1016/j.ecoleng.2017.05.024 0925-8574/© 2017 Elsevier B.V. All rights reserved.