Author: Chris Perez

By Mark T. Unger, CWS-VI The first performance standard for water softeners was the Water Conditioning Foundation’s (WCF) S-100 Standard. The first version was issued in 1959 and contained structural integrity testing to ensure water softeners would not leak when installed in the field at the manufacturer’s recommended operating conditions. Over the years this standard became WQA S-100, added various softening performance testing criteria and became an ANSI-accredited standard in the form of NSF/ANSI 44, Residential Cation Exchange Water Softeners. The current version of NSF/ANSI Standard 44 contains various tests to ensure a certified softener performs as expected. Testing laboratories…

Read More

By Vivekanand Gaur, Ph.D. Introduction Instead of using chlorine, drinking water utilities are gradually switching over to the use of chloramines—in particular, monochloramine—for disinfection of drinking water. Almost any activated carbon in POU devices will remove chlorine taste and odor, but special activated carbons are needed to remove chloramines. Chlorination has been an effective and most popular disinfection method in drinking water supplies. It inhibits the growth of microorganisms like bacteria and viruses, and in turn, saves lives from illnesses caused by such microbes in water. However, chlorine promptly reacts with natural organic matter (NOM) in water to form different…

Read More

By Peter S. Cartwright, P.E. The membrane technology of reverse osmosis has been around for many years now and is finding more and more applications in all aspects of water treatment. This technology couldn’t care less as to the source of the water to be treated; however, its performance and design requirements are significantly affected by the feedwater characteristics and intended use of the treated water. In general, it is useful to divide the feedwater into three categories based on source: Raw water. Water coming from a natural source (well, river, lake, ocean) or a municipal drinking water treatment plant…

Read More

By Jeffrey A. Trogolo, PhD Since 1500 BC, when ancient Egyptians and Hindus first filtered water and medicines with activated carbon (AC), it has been used as a filter to remove impurities from water, air, gases, processed beverages and pharmaceuticals. Today, whether in block or granulated form, activated carbon is still a leading filtration medium in industrial, commercial and consumer water filters, providing end users with water free of undesirable tastes, odors, particulate matter and other impurities. Activated carbon has been the premier water filtration medium for millennia; however, there is still room for improvement. Over the past 30 years,…

Read More

By C.F. ‘Chubb’ Michaud, CWS-VI Ion exchange is versatile When you think about water treatment processes that can remove the dissolved salts from feed streams, there are many options. Ion exchange, reverse osmosis, distillation or electro-deionization (EDI) are all possibilities. But what if you don’t want to remove everything from the water? What if you want to leave something behind for economic or health reasons? What if you want to go between the lines and remove only a particular ion from a mix? Ion exchange has the flexibility to do all of these. Ion exchange works because of ion selectivity,…

Read More

Do they really work and, if so, how? By Gary Hatch, Ph.D. Introduction Chlorine and chlorine compounds Activated charcoal (otherwise referred to as activated carbon) has been known for many years to be a very effective material for dechlorinating water. This process, the chemical removal mechanism(s) and the resulting byproducts have been studied extensively over the last 30 to 40 years. Chlorine and its active oxidative chlorine compounds are capable of being chemically reduced by activated carbon. The primary free chlorine and combined chlorine compounds (derived from ammonia) are listed in Table 1. Free chlorine as ‘molecular chlorine’ is a…

Read More

By Pauli Undesser, CWS-VI The Water Quality Research Foundation (WQRF) released two new reports in February that, in combination with WQRF’s 2009 Study on Benefits of Removal of Water Hardness (Calcium and Magnesium Ions) From a Water Supply (also known as the Battelle Study) are encompassed in a body of research called the Softened Water Benefits Study. The two new reports are: Evaluation of Relative Effects of Hardness, Detergent Dose and Temperature to Evaluate Stain Removal Efficacy and/or Use of Less Laundry Detergent at Lower Water Temperatures (the Laundry Study) and Evaluation of the Effect of Water Hardness on Performance…

Read More

By Matthew Wirth Back in 1979 on my first day of physics class, the first problem the professor proposed to the class was this thought- provoking one: “There is a constant rain outside and you need to get from here in the science building over to your next class in the civil engineering building. Will more raindrops hit you if you walked or if you ran to your next class?” I think what he was truly asking was: “Do second-year engineering students possess any common sense?” This was a valid question. You can image all the profound looks and deep…

Read More

By Filip Rochette Introduction A major manufacturer has developed an innovative ion exchange system for the removal of nitrate from groundwater sources. These systems have become the leading nitrate removal technology in the United Kingdom, with over 50 percent of nitrate removal plants installed in 2006-09. This article describes in detail the system process. Many water utility companies are experiencing ever increasing levels of nitrate in drinking water sources. Utilities that are heavily dependent on groundwater sources beneath arable land are particularly badly affected and in danger of breaching legal limits in many cases. Agricultural sources of nitrates are by…

Read More

By Peter S. Cartwright, P.E., CWS-VI Introduction The crossflow pressure-driven membrane technologies of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) have become key treatment tools in water purification, wastewater recycle/reuse and chemical processing applications. Because they all rely on the passage of water through a semi-permeable membrane to effect separation, the membrane surface is subjected to the accumulation of suspended solids or solute—the material intended to be separated or concentrated from the feed stream. This phenomenon, known as ’fouling,’ is linked to four causes: Plugging. This results from particulate material (dirt, sand, etc.) accumulation on the membrane…

Read More