ITT's Place in the Cycle of Water - Water Solutions

The Cycle of Water: Wastewatertertiary treatment / disinfectionEffluent discharge standards in the early days ofwastewater treatment focused on the removal of solidsand materials that imposed an oxygen demand prior toreturning the water to the environment. Nowadays it ismore common that discharge permits dictate maximumconcentrations of nutrients, principally nitrogen, butincreasingly often include phosphorous. They canbe removed biologically, by introducing anaerobic/anoxic stages where microorganisms are starved ofoxygen. Phosphorus can also be removed by dosingappropriate chemicals to render it insoluble. Nitrogenis further removed by biologically active media filters.Some denitrification systems utilize the advantagesof deep bed, mono-media filters to effectively andefficiently remove nitrogen in wastewater effluent. Inaddition to nitrogen, these denitrification systems cansimultaneously remove suspended solids.Following the primary and secondary treatmentprocesses, the wastewater is typically treated furtherusing advanced filters, chlorine, ozone or ultravioletlight. Natural purification systems, such as reed beds,have also attracted interest due to their sustainablenature. However, these are generally only suitable forsmall systems with sufficient land area. As wastewaterdischarge standards become increasingly stringent,many wastewater plants are incorporating tertiarytreatment processes to their conventional treatmentprocess.Advanced filters, gravity media filters, fine screens orsemi-permeable membranes are a physical barrier usedto remove much of the remaining suspended organicand inorganic solids, as well as many pathogens.Chlorine is the most common method of chemicaldisinfection, injected into the wastewater stream as aliquid or gas. Depending on the characteristics of thewastewater, insufficiently treated flows may containTHM precursors which, when reacted with chlorine,have an increased probability of forming carcinogeniccompounds. Flows not containing THM precursors cansafely and effectively be treated with chlorine.Ozone is a very powerful oxidant that is generated onsitefrom either pure oxygen or air. Ozone inactivatescritical enzymes in the remaining pathogens and itsoxidizing power can also be useful for breaking downpollutants that cannot be biologically degraded, suchas residual pharmaceutical or endocrine-disruptingcompounds.CASE STORY:ITT UV System KeepsNew Zealand Waters SafeTo protect the environment of the flora andfauna in coastal waters as well as safeguardthe health of bathers, the city of Manukauin New Zealand turned to a UV disinfectionsystem from ITT’s WEDECO brand, theworld’s largest such system.ITT’s Place In The Cycle of Water: Everything But The Pipes