The Development of Treatment Method for Plywood Industry Wastewater, Characteristic and Possible Application of the Obtained Coagulates
Jūlija Brovkina

04.01.2013. 13:00, Rīgas Tehniskās universitātes Materiālzinātnes un lietišķās ķīmijas fakultāte, Āzenes iela 14/24, 272. auditorija

Galija Šuļga, Jurijs Ozoliņš

Jānis Zicāns, Sergejs Gaidukovs, Andris Morozovs

Latvia is one of the major plywood manufacturers in Eastern Europe. In recent years, the industry is developing dynamically and aims for the integration in the international economic area, which in turn, requires a serious investment from companies, in order that manufacturing technologies and products could meet international environmental standards. The hydrothermal wood treatment is one of the stages of plywood production, resulting in water being contaminated by components such as hemicellulose, lignin and wood extractive substances (HLES). As a result, the natural pollution of woody tissue are causing higher water coloration and chemical oxygen demand rates. Accordingly, the issue of organasing an effective, local wastewater treatment technologies is becoming topical. Literature review summarises information about wood components (cellulose, lignin, hemicellulose, extractive substances), described the plywood manufacturing process. The information about main points and application of the wastewater treatment methods were analyzed. Evaluating information, the coagulation and ozonation methods are taken as a base. The review summarises extensive information on the availability of the aluminium-containing coagulants. During thesis work a combined application of methods to model wastewater, containing hemicellulose, lignin-containing and wood extractive substances were first studied and evaluated. The model wastewater by its chemical characteristics has imitated sewage of hydrothermal basin of plywood production. In order to find the wood pollutants coagulation patterns and to develop optimal conditions of wastewater treatment technologies, studies of the process of coagulation were completed using the aluminium-containing coagulants. In the course of the work it was found out, that a great extent of advantage belongs to polyaluminium chloride (PAC). Based on the data of aluminium-containing coagulants costs, in accordance to prices, aluminium salts may be placed as follows: Al2(SO4)3 < AlCl3 < PAC. To reduce the PAC costs and increase the efficiency of HLES removal, the new compositions of coagulants were designed on the PAC base. Coagulants composition has the following advantages: low dose, low residual concentration of aluminum in the filtrate and insensitivity against temperature changes. Taking into account a goal of water re-use set, it was necessary to choose a second treatment stage, which would be effective, fast and does not require use of chemical reagents. The method of ozonation was chosen for this task. After use of such combined methods, it was find out that the physico-chemical characteristics of purified water satisfies Latvian State Ministers Cabinet’s regulations to water quality and it can be returned to the technological cycle of plywood production. It should be noted that as a result of the coagulation process, neawly formed coagulates is not seen as an intended for disposal waste, but as a by-product, that can be successfully used in various industries. Coagulates, which consists primarily of hemicellulose, lignin and aluminum, can be prospectively utilized as an additive to clay, to create on its basis efficient sorbents. In the course of the work a clay composition was developed, characterized by high activity against water, oil and heavy metals. The doctoral thesis is written in Latvian, it consists of 159 pages, 51 images, 27 tables, 27 equations, 1 appendix and 323 references were used in the work.

Wastewater from hydrothermal basin, hemicellulose and lignin containing substances, coagulation, aluminium coagulants, ozonation

Brovkina, Jūlija. The Development of Treatment Method for Plywood Industry Wastewater, Characteristic and Possible Application of the Obtained Coagulates. PhD Thesis. Rīga: [RTU], 2012. 159 p.

Publication language
Latvian (lv)
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