Water Well Journal
Issue link: http://read.dmtmag.com/i/767379
Better Maintenance Well biology goes beyond just its influences on water quality. A better understanding of its role in well performance can help establish better maintenance practices and more accu- rate chemical cleaning and disinfection for our wells. Monitoring biofilm growth through quantifying bacterial populations with additional testing centered on determin- ing the composition and maturity of biofilm accumulations gives us a much better indication of the overall fouling potential. Simple quantification techniques can gauge the timeliness of maintenance efforts. This data is also useful in deter- mining better operational practices that can help minimize biological fouling— as idle wells often allow bacterial popu- lations to enter unregulated growth phases that result in a higher fouling potential. A rise in bacterial growth, especially in conjunction with decreased performance, can trigger the need for routine maintenance before fouling be- comes even more problematic. Identification of not just the organ- isms themselves, but also the inorganic and mineral debris trapped within the matrix, can guide the design of treat- ment efforts and the selection of mechanical and chemical techniques. In cases where heavy amounts of mineral constituents are present in the deposit matrix, mineral acids or more stringent mechanical agitation methods may be needed to break apart the more hardened scales. Further, if chemical agents are selected, their required quan- tities can be more closely calculated, keeping costs down and minimizing the risks of damaging well components or aquifer contamination associated with overtreatment. Similar information can also target specific problem areas during mainte- nance, resulting in more efficient use of time and effort with a greater chance of success and reduced risk of redoing costly work in the future. For example, a biofilm with a heavy anaerobic popu- lation may indicate the growth is ad- vanced and likely most prevalent in oxygen-depleted areas within the well. In many wells these areas are found in the deeper depths where flow is re- duced or where sumps are present. More mechanical agitation may be needed there to physically disrupt the deposits, a higher chemical dosage may be used, or perhaps adjusting the pump depth or filling in the sump is needed to remove and prevent the problem from reoccur- ring. In addition, specialty chemicals to enhance traditional cleaning chemistries, such as biodispersants and surfactants, can be selected to supple- ment traditional chlorine treatments to aid in penetrating and disrupting biofilm formations that may have otherwise been undisturbed. A profile of other dominant bacterial species, including those associated with MIC, can also be beneficial in determin- ing ongoing maintenance strategies. Identifying such organisms can expedite maintenance to prevent material degra- dation but also allow for better material selection in those cases where well components are already in need of re- placement. Greenish colony growth on blood agar plate. Water flea feeding on iron oxide entrained biofilm. MICROBIOLOGY continues on page 22 Twitter @WaterWellJournl WWJ January 2017 21