On the design of pulp and paper wastewater treatme

On the design of pulp and paper Sewage Treatment Engineering Abstract: This paper briefly introduces some products of the sewage treatment projects of Guangxi Hexian pulp mill and Yunnan Simao paper mill, which are designed by our institute and constructed with the loan of the Asian Development Bank, and discusses how to solve the problems related to sewage treatment

key words: sewage; Activated sludge process; Surface aeration; Jet aeration; Design

there are various pollutants in pulp and Paper sewage, which are characterized by lower bod/cod value than urban sewage and poor biochemical property of sewage. This requires a reasonable combination of treatment processes for pulping and papermaking wastewater in order to meet the sewage discharge standard. The combination of sewage treatment methods should generally follow the law of "easy first, difficult second, simple first, complex second". For a qualified sewage treatment project, the best combination of several methods should be determined after investigation, research and economic comparison according to the nature of sewage, that is, the quantity and quality of water and the specific requirements of sewage discharge and receiving water body. For special projects, if there are few engineering practices or technical parameters have not been determined, certain scientific experiments and scientific analysis are needed to determine the key parameters for sewage treatment design, so as to ensure the stable and reliable operation of the design process

Guangxi Hexian pulp mill and Yunnan Simao paper mill designed by our institute are projects that purchase equipment and introduce technology through international bidding through applying for loans from the Asian Development Bank. The design scale of the two plants is to produce 50000 tons of bleached kraft pulp per year, and the production raw materials are masson pine and Simao Pine respectively. Among them, the sewage treatment project of Guangxi He county pulp mill adopts the general contracting method for international bidding, with a design scale of 20000 m3/D, and has been put into operation at present; The sewage treatment project of Yunnan Simao paper mill adopts imported technology and purchased equipment for international bidding. The design scale is 18000 m3/D. the project is under commissioning

famous bidders from the United States, Canada, Austria, the Netherlands, Finland, Sweden, Singapore and other countries, as well as equipment manufacturers with good biocompatibility of PHA and well-known domestic design consulting companies and equipment companies participated in the bidding, Among them, the representative sewage treatment methods are:

(1) biological contact oxidation coagulation sedimentation method

(2) biofilter oxidation ditch and activated sludge method

(3) pure oxygen activated sludge method

(4) oxidation pond method

(5) biofilter activated sludge method

(6) oxidation ditch method

(7 we have also reached strategic cooperation agreements on material development with a number of European scientific research institutions) activated sludge method (two-stage aeration, delayed aeration, etc.)

1 Guangxi He county pulp mill sewage treatment project

1.1 process flow (see Figure 1)

Figure 1 surface aeration sewage treatment process

1.2 buildings and structures (see Table 1)

1.3 operation conditions

economic indicators: total investment of US $4.34 million, unit sewage investment of US $217/m3 · D. According to the acceptance report in December 1997, it has operated for 669 days since it was put into operation in December 1994. The economic indicators are as follows (including sludge treatment): the annual cost is 5.7753 million yuan, including 594600 yuan for water and electricity; The consumption of raw materials is 466200

yuan; Labor cost 315000 yuan; Equipment depreciation cost is 4.4 million yuan. Sewage treatment cost: 0.83 yuan/m3, including operation cost: 0.198 yuan/m3

operating conditions: operate according to the design requirements, but no coagulant is added to the secondary sedimentation tank. See Table 2 for operation results

Table 1 construction and List of structures and equipment name

specification m

quantity equipment

quantity

neutralization tank

grille and pump room

cooling tower

primary sedimentation tank

homogenization tank

aeration tank

secondary sedimentation tank

reflux 2014 thin film transistor (TFT) The area of panel demand will increase by 7%. Sludge pump room

sludge thickener

sludge storage tank

sludge dewatering machine room

accident pool

dosing room

comprehensive building

10 × 4.5

18 × 9

φ thirty × 3.2