Advanced Tertiary Nutrient Removal & Reject Water Treatment
Reitsma, G. and Weijma, J., Paques bv, The Netherlands
(free)
Keywords: Reject water treatment, Tertiary treatment, Nutrient removal, Moving bed filtration, Nitrogen removal, Phosphorus removal
INTRODUCTION
There is a growing interest in tertiary treatment and in particular nutrient removal for wastewater
treatment plants, due to increasingly strict final-effluent legislation introduced by the European Water
Framework Directive (WFD). The WFD aims to improve receiving surface water quality, requiring in a
number of cases a significant improvement in wastewater treatment plant performance. Moreover,
topics such as energy consumption and carbon footprint are becoming more and more important in
the design of new and modification of existing sewage treatment works.
ASTRASAND® bio-filtration, an advanced moving bed sand filtration technique, has already made a
significant contribution by helping more than twenty sewage treatment plants in the United Kingdom to
comply in particular with strict nitrogen discharge limits, but also phosphate, suspended solids and
BOD limits. For meeting strict nitrate standards (or Total Nitrogen) there are now four denitrifying
ASTRASAND® filter installations completed and operational in the south of the UK. A key advantage
of this type of tertiary treatment is that several processes are combined in a single process step.
In this paper we would like to share our recent experiences in the United Kingdom with regard to
ammonia and nitrate removal. In addition to this the results of a long-term research project with
ASTRASAND® bio-filtration, conducted by Dutch Waterboards and research institutes, will be shared.
This study shows that NOx removal (< 1 mg/l) simultaneously with PO4 removal (to < 0.15 mg/l) can
be achieved in one filter step at relative high hydraulic loading rates.
Furthermore attention will be paid to digester reject water treatment (dewatering liquors). Ammonia
in sludge liquors represents a relative large fraction (10-30%) of the total nutrient loading on sewage
treatment works. ANAMMOX® is the process for cost-effective nitrogen removal. The process assists
Waterboards with their actions to decrease energy consumption and carbon footprint of sewage
treatment works. The ANAMMOX® process is now successfully applied at seven wastewater
treatment plants.
