Optimization of biomass harvesting of microalgae, Chlorella sp. utilizing auto-flocculating microalgae, Ankistrodesmus sp. as bio- flocculant Fathurrahman Lananan a , Fareza Hanis Mohd Yunos a , Nurfarahana Mohdm Nasir a , Nur Syuhada Abu Bakar a , Su Shiung Lam a, b , Ahmad Jusoh a, b, * a School of Ocean Engineering, Universiti Malaysia Terengganu, Terengganu 21030, Malaysia b Institute of Tropical Aquaculture, Universiti Malaysia Terengganu, Terengganu 21030, Malaysia article info Article history: Received 5 January 2016 Received in revised form 18 April 2016 Accepted 18 April 2016 Available online xxx Keywords: Microalgae Harvesting Auto-flocculating Chlorella sp. Ankistrodesmus sp. abstract Current microalgae harvesting technology depends on sophisticated and complex approaches such as hollow fiber filtration, chemical flocculants and centrifugation, which are deemed feasible if high value products were obtained. In this study the potential of auto-flocculating microalgae Ankistrodesmus sp. was examined for its potential as bio-flocculant to harvest Chlorella sp. Zeta Potential Analysis was performed on the microalgae in the pH range of 4.16e9.55 before subjecting the microalgae to the coagulation e flocculation assay. The isoelectric point of microalgae suspension was observed in the range of pH 5e8 and the magnitude of zeta potentials ranged between 10 mv to 35 mV. Ankis- trodesmus sp. was inoculated at a dosage of 50% (v/v) into a batch of Chlorella sp. culture during the coagulation e flocculation assay. The removal efficiency shown by Ankistrodesmus sp. was 82% at pH 7.1 followed by 55% at pH 6.2. Utilizing Ankistrodesmus sp. for flocculation was efficient since it did not require any changes of pH because isoelectric point was observed within the normal pH of Chlorella sp. growth condition. Development of innovative microalgae treatment technology incorporating contin- uous bio-harvesting with microalgae-microalgae flocculation could provide a low-cost and sustainable wastewater treatment approach. In addition, the use of microalgae itself to harvest microalgae biomass harvesting could simplify downstream processing, saving resources and would reduce the production cost for future microalgae-based technology. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Modern aquaculture mainly consists of the rearing of aquacul- ture species intensively which allows the production of high den- sity aquaculture species within very limited space (Lam et al., 2015). However, this leads to the release of highly concentrated waste- water to the environment as compared the traditional extensive aquaculture and this has led to higher risks of environmental pollution (Lam et al., 2008). Cao et al. (2007) reported that aqua- culture is the major contributor to the increasing levels of organic waste and toxic compounds. Without proper treatment and man- agement, aquaculture waste could potentially cause newly emerging diseases due to antibiotic resistance and algal bloom (Hegaret, 2008; Rubert, 2008). The release of untreated wastewater poses serious environ- mental challenges to the receiving water bodies (Arora and Saxena, 2005; de-Bashan and Bashan, 2010). The major effect of releasing wastewater rich in organic compounds and inorganic chemicals is mainly eutrophication (de-Bashan et al., 2002; Godos et al., 2009; Mulbry et al., 2008; Pizarro et al., 2006). Denitrification plays a role in removing unwanted nitrates from the wastewater effluent, thus reducing the changes of the water discharged from treatment plants that can cause undesirable consequences such as algal bloom. The occurring of eutrophication in lakes and reservoir produces unsightly scums of algae on water surface and it can oc- casionally result in increased fish mortality by depriving it of oxy- gen as they use dissolved oxygen in their decomposition process. * Corresponding author. School of Ocean Engineering, Universiti Malaysia Ter- engganu, Terengganu 21030, Malaysia. E-mail addresses: gsk1147@pps.umt.edu.my (F. Lananan), farezahanis@gmail. com (F.H. Mohd Yunos), farrah7690@gmail.com (N. Mohdm Nasir), nursyuhadabakar@gmail.com (N.S. Abu Bakar), lam@umt.edu.my (S.S. Lam), ahmadj@umt.edu.my (A. Jusoh). Contents lists available at ScienceDirect International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod http://dx.doi.org/10.1016/j.ibiod.2016.04.022 0964-8305/© 2016 Elsevier Ltd. All rights reserved. International Biodeterioration & Biodegradation xxx (2016) 1e6 Please cite this article in press as: Lananan, F., et al., Optimization of biomass harvesting of microalgae, Chlorella sp. utilizing auto-flocculating microalgae, Ankistrodesmus sp. as bio-flocculant, International Biodeterioration & Biodegradation (2016), http://dx.doi.org/10.1016/ j.ibiod.2016.04.022