Water Innovate has more exciting new technologies in the pipeline
Dr Steve Callister
Since the launch of Water Innovate Ltd. last spring, products from its impressive portfolio of technologies have been released. We review the Company’s development to date and outline the technologies available.
The effective combination of a dynamic approach coupled with the necessary financial backing has enabled Water Innovate to offer a range of exciting products that are set to revolutionise various sectors of the water industry. The initial products marketed are described below. We look at their key features and the current state of their development.
This is a revolutionary odour emission modelling software package that predicts formation and emission of H2S from sewage treatment works. The software is unique in producing dynamic predictions that demonstrate variation of emission rate over time. It can help generate accurate and meaningful odour contour plots in dispersion modelling packages.
The product was launched at IWEX last October and is now being proactively marketed to all utilities and consultants along with a process modelling service providing specialist in-house expertise. Positive feedback is being received from the marketplace and Water Innovate is currently in the final stages of negotiating a number of significant contracts. The Company has employed an additional process modeller to handle the growing workload.
ODOURsim® is an essential design tool aiding the development of defensible odour management plans and abatement strategies for existing and planned installations. Because the product is compatible with existing dispersion models its adoption is relatively simple.
The use of dispersion models to predict odour concentrations from sewage treatment works is commonplace. The resulting odour contour plots are often used in support of planning applications. The models can also be used to make decisions about site specific odour control technologies.
However, it is critical to regard each element in the odour annoyance pathway (see right) with equal importance. An over-emphasis on dispersion modelling can give inaccurate predictions. ODOURsim® was developed because of this over-emphasis on dispersion modelling and the lack of attention given to inputs to dispersion models.
The software allows the dynamic impact of flow, quality and meteorological variables on emission rates to be examined, avoiding the inaccuracies inherent in using a constant H2S dispersion rate, through mechanistic modelling of variable H2S formation and emission. ODOURsim® employs a liquid-phase H2S model and uses mass-transfer calculations for various process components.
Variations in wastewater flow and quality at a treatment works inlet can lead to significant differences in influent odorant concentrations and emissions from downstream processes. To illustrate these effects, ODOURsim® has been used to model a sewer feeding a set of primary sedimentation tanks. The software reveals emission peaks at high flow conditions because the sewer flows full, allowing H2S to form under anaerobic conditions, and because high flows enhance emissions from the sedimentation tank weirs (Figure 2).
Figure 2: Emission peaks for the sewer and sedimentation tank system
These large variations have implications for when odour measurements are taken. If spot measurements were being inputted into dispersion models, the time of measurement would be crucial. But because ODOURsim® is dynamic, the impact over time of variables on emission rates can be predicted. It is essential for emission variations to be included in odour modelling exercise because when significant variations in emission rate exist, deviations can radically alter odour footprint.
The patented N-Tox® nitrification toxicity monitor provides early warning of wastewater treatment works breakdown and helps prevent ammonia pollution of the aqueous environment. The monitor avoids problems associated with probe fouling because it relies upon gas-phase detection of dinitrogen oxide (N2O) rather than detection of a chemical in the aqueous phase.
A final pre-production prototype is now under test at Cranfield University’s Pilot Hall facility. Water Innovate has advanced orders for units from major industrial customers under long term service contracts. The innovative design now comprises an integral sample pump, gas conditioning device, non-dispersive IR gas analyser, auto-calibration system and data logging unit, housed within an IP65 enclosure.
Prior research at Cranfield demonstrated that N2O is rapidly detected when nitrification starts to fail. The rate of N2O production is linked to oxygen depletion and ammonia shock loading. Increases in dinitrogen oxide levels are directly related to nitrification failure. Hence, measurement of the N2O off-gas level allows the monitoring of nitrification performance to prevent release of ammonia.
Using N-Tox® to detect an increase of N2O above the start of an activated sludge aeration lane means that at least one hydraulic retention time of the final clarifier would pass before nitrification failure. Figure 3 demonstrates that the time lag between detection of increased N2O, and the appearance of ammonia provides typically seven hours warning of nitrification failure.
Figure 3: This graph shows what happens when a short aeration failure occurs in an activated sludge plant. The N-Tox® alarm allows time for remedial action to be taken.
Once a failure is detected, a number of process options can be followed to restore nitrification including increasing aeration rates, bypassing influent to storm tanks, or returning high ammonia liquors to the works inlet.
The key markets for N-Tox® are municipal sewage and industrial effluent treatment. Many treatment works that discharge direct to the aqueous environment are consented for ammonia at < 5 mg/l. These plants rely on ammonia removal through bacterial conversion to nitrate.
Inhibition by aeration failure, toxic chemicals or high ammonia concentrations can result in a wastewater treatment works not meeting its required ammonia consent. Some industrial effluents, such as landfill leachate or pharmaceutical wastewaters, have high ammonia levels. The requirement for an N-Tox® alarm here is critical as the consequences of nitrification failure are more serious.
The N-Tox® monitoring system provides an effective alternative to other methods of nitrification failure detection (such as ammonia probes or on-line respirometry) by providing an earlier warning. Plant operators are alerted to problems early so that remedial action can be taken.
Special zirconium compounds have been used to develop ZR-Coag®, a product that enables high efficiency coagulation of potable supplies and waste treatment effluents.
DWI approval for use in drinking water treatment has been applied for, as well as international patents, and Water Innovate has put in place a secure and robust supply chain to bring ZR-Coag® into the UK market during 2006.
Any water or wastewater treatment process that currently uses iron or aluminium based coagulants is a potential application for ZR-Coag®. These coagulants characteristically dissociate into strongly charged ions and their charge density is a significant factor in determining coagulation and particle removal efficiency.
Zirconium ions are more effective as coagulants because they have a 4+ charge, which is more charge per mole than the 3+ charge of iron and aluminium. Also, they exhibit a lower tendency to dissociate into lower charged intermediates, or complete hydrolysis species, over a broader pH range than either iron or aluminium.
The higher charge density of ZR-Coag® significantly improves the charge neutralisation coagulation mechanism, resulting in enhanced organic and suspended particle removal. This can be achieved at lower dose rates, with less pH adjustment and sludge production. Larger flocs are produced that are easier to separate, allowing subsequent separation systems to be operated at higher flow rates.
ZR-Coag® was originally developed with a specific focus on NOM removal from upland waters, but it is equally applicable to removal of other pollutants including turbidity, DOC and colour. Applications include industrial processes that treat effluents or process liquids by using coagulants to aid the removal of organics and suspended or colloidal negatively charged particles, and ZR-Coag® can be effectively employed in membrane pre-filtration applications utilising enhanced coagulation techniques.
Coagulants are increasingly used in municipal sewage treatment works either to improve the performance of sedimentation processes for suspended solids removal, or to reduce phosphate concentrations to satisfy the requirements of the Urban Wastewater Treatment Directive.
To further demonstrate the effectiveness of ZR-Coag®, trials with two water companies are ongoing. The first trial is examining the use of ZR-Coag® as a seasonal substitute for ferric sulphate during periods of very high colour in upland raw water supplies. The second trial is investigating suitability of the product for phosphate removal in wastewater treatment.
Three advanced tertiary treatment technologies are currently being developed.
The Membrane Chemical Reactor MC-R™ is an innovation combining UV and titanium dioxide to remove pollutants from high COD and coloured effluents. Water Innovate has been successful in obtaining a DTI Technology Programme grant for development of the technology under the Waste Management and Minimisation initiative. This is part of a large collaborative project to develop a solution to treating waste cutting oil from the metal finishing industry.
The second technology is the Odour Extraction Membrane Reactor OEM-R™. It is a new process that will remove odour causing molecules, with applications in sewage, waste management, and oil and gas sectors. Finally, the Nitrification-Denitrification Reactor ND-R™is a novel technology for removing nitrogen from wastewater, avoiding the need for chemical additives.
The initial focus has been on commercialising ODOURsim®, N-Tox® and ZR-Coag® and taking them to market either directly or through licensing deals. During 2006 the Company will be investing significant resources in further development of the remaining technologies, as well as in evaluating opportunities to acquire additional portfolios of water related technology to commercialise.
Steve Callister is Managing Director at Water Innovate Ltd. Visit www.waterinnovate.co.uk or telephone 01234 756014 for further details.