Implementation of The LSP-concept in Extended Aeration

English Summary – Implementation of The LSP-concept in
Extended Aeration Activated Sludge Treatment Plants in
the Pulp and Paper Industry
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Key words - aerobic treatment, sludge yield, activated sludge, pulp and paper
industry effluent, Low Sludge Production
Introduction
The Low Sludge Production (LSP) process is an aerobic treatment process based on
a new principle. The wastewater is treated in two consecutive stages. The first stage,
the bacterial stage, is designed and operated to favour the growth of dispersed
bacteria, which consume the major part of the soluble organic matter in the effluent.
The second stage, the predator stage, is an activated sludge stage designed and
optimized for the growth of filter feeding microbes, which consume the bacteria
from the first stage. The result is expected to be a significant decrease in production
of bio sludge in combination with improved sludge settleability.
This master thesis is a part of a project where Anox AB and ÅF-IPK investigates the
possibilities to implement the LSP-concept in extended aeration activated sludge
treatment plants in the pulp and paper industry.
Theory
Most pulp and paper industries in Sweden use biological treatment to remove
organic matter from their effluents, thereby reducing the discharge of Biological
Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). Biological
treatment is based on the use of micro-organisms, which convert organic matter to
carbon dioxide and water. Large amounts of energy are released in the oxidation and
consequently large amount of biomass can be formed. The reactions can be summed
as follows:
Organic matter + O 2 Æ CO 2 + H 2 O + energy
Organic matter + energy Æ biomass
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