Potential use of rice starch in coagulation–flocculation process of agro-industrial wastewater: Treatment performance and flocs characterization

• Published in: Ecological engineering 2014-10, Vol.71, p.509-519
• Main Authors: Teh, Chee Yang, Wu, Ta Yeong, Juan, Joon Ching
• Format: Article
• Language: English
• Subjects: Alum; Animal, plant and microbial ecology; Applied ecology; Applied sciences; Biological and medical sciences; Coagulant; Conservation, protection and management of environment and wildlife; Environmental degradation: ecosystems survey and restoration; Exact sciences and technology; Flocculant; Fundamental and applied biological sciences. Psychology; Palm oil mill effluent (POME); Pollution; Rice starch; Wastewater treatment; Wastewaters; Water treatment and pollution
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2014.07.005

•Unmodified rice starch could be used as a natural coagulant in POME treatment.•Flocs formed by rice starch showed higher settleability as compared to alum.•Combination between rice starch and alum reduced both dosages with high TSS removal.•Both coagulants and flocs were characterized by FTIR, TGA and SEM. The present study investigated the use of starch to replace inorganic coagulants for the treatment of agro-industrial wastewater from palm oil mill, namely palm oil mill effluent (POME). Rice starch was found to be the best starch because it yielded similar total suspended solids (TSS) removal as alum, significantly shortened the settling time and produced flocs with higher resistance towards stronger shear force. The use of rice starch alone in room temperature enabled the removal of TSS up to 84.1% using the recommended values of dosage, initial pH, settling time and slow stirring speed at 2g/L, pH 3, 5min and 10rpm, respectively. Higher TSS removal of 88.4% could still be achieved at lower dosage of rice starch (0.55g/L) only when rice starch was used together with 0.2g/L of alum during the treatment of POME. To gain further insights on the properties of coagulants and flocs produced from the treatment, characterization methods such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used.