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Browsing Pusat Pengajian Kejuruteraan Kimia - Tesis by Author "Aaron, Koe Zhen Yao"

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    Nutrients recovery from freshwater aquaculture effluent via zeolite assisted forward osmosis
    (2024-08-01)
    Aaron, Koe Zhen Yao
    The increased generation of inland aquaculture effluent gives rise to the importance of nutrient recovery from said effluents. Freshwater fish farm effluent consists of dilute nutrients, such as ammonium, NH4 + and phosphate, PO4 3- ions. The treatment of aquaculture effluent is crucial as irresponsible discharge of them will cause ecological imbalances, such as eutrophication and hyper nitrification. The complex nature of aquaculture effluent and its trace content are the obstacle for nutrient recovery due to the presence of various cations in the wastewater. This study demonstrated the potential of PO4 3- recovery via chemical precipitation by using a forward osmosis (FO) process system with the assistance of zeolite. NH4 + recovery was also conducted via zeolite regeneration. Preliminary studies of FO operations concluded that NH4 + transport across membrane layer is dependent on self-diffusion flux and diffusion flux induced by reverse Mg2+ flux while PO4 3- flux was mainly contributed by convective flux. Although membrane orientation with active layer facing draw side exhibited higher water flux, the rejections of NH4 + showed similar values with FO mode. Preliminary studies showed that the two-step Mg-zeolite Y sorption process successfully supplied Mg2+ into the feed solution and improved the NH4 + rejection for the FO process while exhibiting zero sorption capacity for PO4 3- . The overall rejection for NH4 + and PO4 3- for seawater driven zeolite-assisted FO process remained relatively high at 94.8% and 98.6%, respectively. PO4 3- recovery studies concluded that concentrated solution from zeolite-assisted FO process (Mg rich solution) with solution pH at 10.5 showed the optimum precipitation results. The results obtained were 98.46% PO4 3- recovery, 0.51 g of solid/L of solution, and