Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/721218
24 WET NEWS SEPTEMBER 2016 The build-up of iron or manganese related bacteria can seriously, affecting pump capacity, water quality and borehole service life. The challenge: Improving borehole yield INSIGHT Pumps & valves The challenge is to develop bio-fouling treatments that are faster acting and more powerful, yet also safe and economic to administer while being environmentally sound • U nder-performance of a borehole can be extremely disruptive and have economic impacts for people and businesses that rely on them whether for irrigation, farming, ground heat extraction, dewatering, domestic use or potable water supply. Poor yield from a water well or borehole can happen for a number of reasons. These include inadequate well design, faulty or underspecified pumps and equipment, poor installation, dewatering or other aquifer issues, or system slowing and degradation from silting, corrosion and clogging. One of the most prevalent causes is the naturally occurring process of bio-fouling – the build-up of iron or manganese related bacteria which can seriously affect pump capacity, water quality and borehole service life. Bio-fouling manifests itself in the growth of bio-mass, the accumulation of living and dead bacteria which creates slime deposits within and around the borehole. The biomass blocks fissures, screens and pump intakes and pipes as it becomes established within the well. Water quality is affected; it may turn a tell-tale reddish-brown, o€en accompanied by an unpleasant taste and odour. Pump output slows, capacity is lost and the well could even become beyond rehabilitation, necessitating complete replacement. The aggregation of the bio- mass initially acts as a natural biological filter, improving the quality of the water entering the borehole by removing iron and other metals along with organics. But as it grows, there is typically a reduction in the specific capacity of the borehole and the chemistry of the water changes. Bio-fouling may affect part or most of the borehole installation, and could lie deep within the system. Hazardous levels of bacteria may also be forming without any obvious indications at the surface. The bacteria are protected by biofilm which can slowly release the bacteria causing water contamination and potential health risks in drinking water wells. Maintenance intervention is generally recommended before the loss in borehole performance reaches 25%. There are a range of modern treatments for the removal of bio-fouling, depending on the severity of the infestation. Many of today's proprietary acid based treatments are generally designed for easy administering by the customer and are environmentally safe when correctly used. Where a more aggressive clean is required, chemical treatment may need to be supplemented by mechanical cleaning, such as jetting, scraping or wire brushing. In the case of severe fouling, stripping with a mineral acid, typically hydrochloric acid, may be necessary together with mechanical surging using surge blocks or jetting tools to increase surface contact. The disadvantage of hydrochloric acid is that it is highly corrosive, and can emit dangerous gasses when used. Shock chlorination is another option using chlorine based disinfectants, but these do not penetrate deep into the biofilm unless used in conjunction with strong mechanical agitation to facilitate increased surface contact. Ultimately, flagging output or downtime from a borehole has cost and operational impacts for the customer. The challenge is to develop treatments that are faster acting and more powerful, yet also safe and economic to administer while being environmentally sound. The availability of more user friendly, added value treatments could also encourage the adoption of more frequent and effective preventative maintenance regimes that will see the best cost returns over borehole service life. In terms of the economics, a sound and systematic approach to maintenance can be around 10% of the cost of calling in a rehabilitation specialist. Effective, regular cleaning to keep bio-fouling at bay will avoid the potential catastrophe and significant costs of leaving a borehole to clog beyond recovery and require replacement. THE CONCEPT • Powerful, fast-acting crystalline powder for more effective treatment of bio-fouling • Improved physical properties that sustain cleaning reactions down the borehole for consistent removal of heavy iron / manganese oxide deposits • Special formulation produced and batched in the UK under an ISO 9001 QA system, ensuring reliable supply and fast availability • Organic and environment- safe product - neutralised once it has reacted with the iron or manganese • Two easy-to-use systems: I-GON 3 for insitu downhole cleaning; I-GON 2 for component cleaning NEED TO KNOW 1 Easy dosing, fast working cleaning agent that restores borehole performance with minimised downtime 2 Regain in pump output seen within as little as 30 minutes 3 Boreholes can be treated overnight and resume full operation the next day 4 Supplied as crystalline powder which dissolves iron related bacteria deposits in solution and is simply pumped from the borehole on completion 5 Suitable for the cleaning of drilling and test pumping equipment to avoid bacterial cross contamination at a new project. THE VERDICT "The golf club were very impressed with the improvement and we'll certainly be using I-GON 3 in the future" Darren Hogben, director of HWS Clogging and build-up of iron bacteria on pump intake The greater proportion of losses in production efficiency in water wells is generally associated with bio-fouling Bio-degradable and safe to use, I-GON3 is safe for use in drinking water wells