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Publikācija: Comparative Effect of Polyaluminium Chloride and Its Composition with Sulphate Aluminuim on Wood Processing Wastewater Coagulation

Publication Type Conference paper
Funding for basic activity Unknown
Defending: ,
Publication language English (en)
Title in original language Comparative Effect of Polyaluminium Chloride and Its Composition with Sulphate Aluminuim on Wood Processing Wastewater Coagulation
Field of research 2. Engineering and technology
Sub-field of research 2.4 Chemical engineering
Authors Galia Shulga
Jūlija Brovkina
Sanita Vītoliņa
Sandra Ostrovska
Jurijs Ozoliņš
Romāns Neilands
Keywords coagulation
Abstract Veneer production includes the hydrothermal treatment of wood in special basins. The wastewater of these basins has a high contamination, because it contains wood originated impurities such as lignin, hemicelluloses and extractive substances, forming waste wood biomass (WB), which is responsible for the high values of chemical oxygen demand (COD) and colour degree of the wastewater. Keeping in mind the zero waste policy for rational use of bioresources and the possible usage of waste wood matter in practice, it is very important to remove quantitatively the formed biomass from the basin’s wastewater. Chemical methods of wastewater treatment with inorganic coagulants are often applied, and aluminium salts as effective coagulants take a honourable place among them. Polyaluminium chloride (PAC) is a very effective, but expensive coagulant, which is used for the treatment of drinking water. In water. PAC undergoes hydrolysis and polymerization reactions, resulting in the formation of polvcations (e.g. [A104Ali2(0H)24(0H2)i2l7+ ). which represent polynuclear aluminium complexes. Its coagulation action can be divided in two distinct mechanisms: charge neutralization of negatively charged impurities by the formed polynuclear aluminium complexes and adsorption of impurities at an amorphous complexes precipitate. The aim of the study was to compare the effectiveness of biomass extraction from the model wastewater of the wood hydrothermal treatment, using separately PAC and its different compositions with a cheaper coagulant such as Al2(S04)3. The hydrothermal hydrolysis of wood was done in a weak alkaline medium at the modulus 1/50, 90°C for 4 h. The obtained birch wood hydrolyzate, imitating the wastewater, contained 1400 mg L'1 of dry solids and had the pi I 9. Polvaiuminium chloride (POLYPACS-30), A12(S04)3*16 H20 and their compositions were used for WB recovery'. The coagulation efficiency was defined after 2 h of the system settling and Nitration. The effectiveness of the wastewater purification was determined at the pH 6 and a dose of 100 mg L'1. which were the optimal for PAC. COD and the colour of the purified solution were determined by ISO 6060:1989 and ISO 7887:1994, respectively. The efficiency of the wastewater treatment was calculated in terms of removal (%), based on the initial and final values of the content of WB, lignin. as well as COD and colour index. It was found that the efficiency of the wastewater treatment sufficiently depended on the mass ratio of PAC.' to A12(S04)3 in the composite coagulant and had a non-linear dependence on the coagulant composition. At the optimal composition of the composite coagulants, the increase in WB removal was 33% and 47% relative to PAC and A12(S04)3, respectively, the increase in lignin removal varied from 28% to 43%, COD diminished from 401 mgO L'1 to 368 mgO L ’. but colour removal increased from 24% to 35%. The additional usage of ozonation after the coagulation purified the wastewater to a greater extent in comparison with the coagulation alone. According to the obtained results of dynamic light scattering, the ozoned wastewater after coagulation with the composite coagulant, having the optimal composition, was characterized by the narrow unimodai particle size distribution with the particle size < 100 nm, the zeta potential of which had low positive values. Thus, it was established that the composite coagulant, which was cheaper than PAC, exhibited better coagulation performance, when compared with simple PAC in terms of the parameters of wastewater purification.
Hyperlink: http://www.pmi.lv/Assets/Files/AbstractBookMCM2012.pdf#page=195 
Reference Shulga, G., Brovkina, J., Vītoliņa, S., Ostrovska, S., Ozoliņš, J., Neilands, R. Comparative Effect of Polyaluminium Chloride and Its Composition with Sulphate Aluminuim on Wood Processing Wastewater Coagulation. In: The XVII International Conference on Mechanics of Composite Materials: Book of Abstracts, Latvia, Riga, 28 May-1 Jun., 2012. Riga: Institute of Polymer Mechanics. University of Latvia, 2012, pp.195-195.
ID 13211