Structure, Morphological, and Physicochemical Characteristics of a New Composite Coagulant Made From Polyaluminium Chloride and Agro-waste of Tapioca Peel

A combination of a metal coagulant with an organic polymer can complement both the outstanding and flaw properties of the separate elements. A novel composite coagulant of polyaluminium chloride (PAC)-tapioca peel extract powder (TPP) called PACTPP with different weights ratio was prepared in this study. In the preliminary study, PACTPPg at the weight/weight ratio of TPP/Al=3.71 was selected as the optimum one based on the performance in treating wastewater sample of landfill leachate. Through all characterisation analyses, it revealed that the novel composite reagent exhibits better coagulant properties when compared with the individual coagulants of PAC and TPP. It was characterised that PACTPPg had combined the best benefits from PAC and TPP, with an acidic property of pH 3.45, the low charge density of 3.45 mV, the higher molecular weight of 1.59 × 107 g/mol, the bigger particle size of 4.528 × 104 d.mn, and a longer connected and compact structure. Through Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, PACTPPg was identified to comprise new chemical compounds, i.e., the functional groups of ketones, aldehydes, and alkanes in a semi-formed crystalline phase. Based on the comparison study, it can be concluded that PACTPPg showed a correlation to encompass the complex interpenetration networks rather than just a simple mechanical mixing of raw materials.

Application of Composite Pre-Polymerized Coagulants for the Treatment of High-Strength Industrial Wastewaters

The aim of this study was the investigation of alternative pre-polymerized coagulants for the treatment of high-strength industrial wastewaters, such as those created by tanneries, or by yeast production industries. The novel inorganic composite coagulant examined in this study (as well as variations of it) was denoted as PSiFAC1.5-10-15. The contribution of a typical polyelectrolyte to improve the effectiveness of the coagulation/flocculation (C/F) process was additionally studied, either by adding it separately (i.e., as a flocculant aid) or by co-polymerizing it within the structure of inorganic coagulant (denoted as PAPEFAC1.5-10-15). It was found that the PSiFAC1.5:10:15 coagulant, either with or without the addition of polyelectrolyte, can provide better efficiency for the C/F process than the conventional coagulants. For example, the addition of 80 mg Al/L in yeast production wastewater samples resulted in a 56% reduction of COD, 40% of turbidity, and 43% of phosphates, regarding the pre-treated anaerobically wastewater samples and reduced by an extra 22%, 14%, and 38% for the pre-treated anaerobically plus aerobically wastewater samples, respectively. The residual aluminum concentration in the treated wastewaters was found to be below the legislation limit of 200 μg Al/L. The characterization of coagulants showed the relatively higher Al13 content of 51% and 43% for the cases of PSiFAC1.5-10-15 and PAPEFAC1.5-10-15, respectively, accompanied by the high zeta-potential measurements (50.5 and 39.5 mV).