66    TREATABILITY OF WASTEPAPER PULPING
PROCESS WASTEWATER
Isik Kabdasli, Assistant Professor
Olcay Tiinay, Professor
Nursen Kldem. Chemical Engineer
istanbul Technical University
Civil Engineering Faculty
Environmental Engineering Department
Maslak, Istanbul, Turkey
INTRODUCTION
Increasing efforts to conserve the natural resources have triggered recovery applications in industries. The pulp and paper industry is an important category in terms of both conservation of
natural resources and recovery potential of the raw material. Therefore, paper and hardboard production from wastepaper is an increasing application all over the world. The wastewater originating from this industry has high organic and suspended solids loads. The treatment requirement is
also significant in that chemical and biological methods and their combinations are utilized to
meet direct discharge standards. In spite of a high level of treatment, the residual COD and color
of the effluent may still be a problem.
The plant studied produces hardboard using clean wastepaper mostly from printing workshops. The capacity of the plant is 20 tons of hardboard per day. Production begins with the
pulping process. The process is the mechanical cut up of the raw material mixed with water. The
pulp is then stored and fed to the paper machine through a grit remover. The paper machine is a
standard Fourdrinier type. The Whitewater originating from paper machine is recycled to the
pulping process after settling. The wastewater is withdrawn from the settling tank. The daily
amount of wastewater is 100 m-Vday, 5 m-Vton of hardboard. The unit wastewater figure is within
the range of 4-10 m3/ton of hardboard given in the literature.1-2
Wastewater characterization of the plant is given in Table I. The characterization of wastewater indicated the variable nature of the wastewater. Soluble COD/total COD ratio is almost
constant and is between 0.7 and 0.8; also, VSS/TSS ratio is unchanged and between 0.55 and
0.64. Kroiss et al.] gives the character of a similar wastewater after settling as 2000-2800 mg/L
COD and 400 mg/L TSS. Our wastewater quality does not change with gravity settling; therefore, COD and TSS values are in the same order of magnitude. Waste loads are also in accordance with the U.S. EPA2 raw waste loads given for paperboard from the wastepaper subcategory.
Settling and biological treatment are the standard treatment methods applied for these wastewaters. On the other hand, a new process called the Bioferric, process has the advantage of compensating variable waste loads, as well as improving the settling characteristics in the activated
sludge process.
In this study, treatability of the wastewater from the pulping process is investigated using
chemical precipitation, biological treatment, and their combinations. The applicability of the bio-
ferric process is also tested.
51st Purdue Industrial Waste Conference Proceedings. 1996, Ann Arbor Press. Inc.. Chelsea, Michigan 48118.
Printed in U.S.A.
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