Innovation Zone: NUTREM Biological Nutrient Removal
This month, we look at an enhanced version of SBR technology which can remove P and other nutrients from wastewater
What is it?
NUTREM, developed by Hampshire-based Plantwork Systems, is an advanced activated sludge process which is capable of removing nutrients such as phosphorus and nitrogen to low levels without any requirement for chemical dosing. It is an evolution of sequential batch reactor (SBR) technology, enhanced to provide ideal conditions for simultaneous nitrification and denitrification as well as for the development of PAOs (phosphorus accumulating organisms).
How does it work?
Raw wastewater is screened before arriving in a balance tank/fermenter; it is then transferred to the reactors in batches for processing. The reactors use a series of phases to treat the wastewater, including anaerobic mix/fill/decant, two aerobic mixes, an anoxic mix and a settlement period. During a period of aerobic mixing with DO levels increased, the PAOs perform luxury uptake of phosphorus. Additional volatile fatty acids (VFAs) generated in the balance tank/fermenter ensure that enough food is available for the PAOs to perform their important task. The clean effluent is decanted via a specially designed syphon decanter, while surplus activated sludge is removed for thickening prior to being delivered to a storage tank.
What’s innovative about it?
The key enhancement to a first generation SBR is the balancing tank which allows COD to be fermented to volatile fatty acids, boosting the performance of the PAOs; the hyperboloid mixers provide a more efficient method of mixing and aerating than a combined FBDA and mixer system. The NUTREM plant also boasts superior process control and should be an attractive proposition for small to medium sized plants of up to 100,000 P/E, for which other biological nutrient removal technologies are not a good fit.
Who is using it at the moment?
There is a 350 P/E demonstration facility at Southern Water’s Wastewater Treatment Plant at Petersfield. This site is used by the University of Portsmouth for research projects. NUTREM has recently been accepted on to UKWIR’s PR14 trials and the research organisation is funding expansion work on the site to assist with further testing under this programme.
What benefits does it bring?
NUTREM is capable of consistently removing TP to concentrations of 0.3 mg/l and below. Its design means that it is highly resistant to shock loads, while it has a modular construction and a small footprint with no primary or tertiary clarifiers required.
What associated technologies are available?
Plantwork Systems also market the de Hoxar Spiral Separator, a compact gravity settlement device for sludge removal and thickening, and Filtration+, a low maintenance and mobile solution for final effluent polishing and the elimination of suspended solids.
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