Liquid chemical feed water treatment

STABREX is easier and simpler to use compared to any other oxidant available for industrial water treatment. The product is pumped directly from returnable transporters (PortaFeed Systems)17 with standard chemical feed equipment. Previously, the only practical ways to apply bromine were to oxidize bromide solutions on-site with chlorine in dual liquid feed systems, or with one of the solid organically-stabilized bromine products applied from sidestream erosion feeders. The former is cumbersome and complex, and the latter is prone to dusting and difficult to control. Other oxidants require complex handling and feed of toxic volatile gases, unstable liquids, multiple-component products, or reactive solids. Simplicity in use results in reduced risk to workers and to the environment. 

Nearly every chemical manufacturing operation requires the use of separation processes to recover and purify the desired product. In most circumstances, the efficiency of the separation process has a significant impact on both the quality and the cost of the product (1). Liquid-phase adsorption has long been used for the removal of contaminants present at low concentrations in process streams. In most cases, the objective is to remove a specific feed component alternatively, the contaminants are not well defined, and the objective is the improvement of feed quality defined by color, taste, odor, and storage stability (2-5) (see Wastes, industrial, Water, industrial water treatment). 

The experimental procedures to establish water treatment plant operational practices have not been without problems. A few of these problems were engineering in nature, such as material compatibility, type of pumps, chemical phase (liquid or solid). Feeding fluoride is like feeding other chemicals experience provides insight in determining the best type of equipment. The feed equipment is in general the same equipment used for feeding alum, soda ash, lime, sulfuric acid, or other chemicals. 

Pervaporation is a membrane process in which a liquid is maintained on the feed side of a membrane and permeate is removed as a vapor on the downstream side of the membrane. Pervaporation is used, because of its low energy consumption and low cost, to separate dissolved organics from water, purify waste water or volatile chemicals, and break azeotropes. Pervaporation plants range from processing a few grams per hour up to thousands of tons per year. For waste water treatment flow of less than 76 L min pervaporation is more cost-effective than other treatment options, such as chemical oxidation, ultraviolet destruction, air stripping followed by carbon adsorption, steam stripping, or distillation/incineration [262]. 

Chlorine dioxide is produced on-site, as needed, for the application. At least two chemicals are combined to form chlorine dioxide. While a few proprietary chlorine dioxide feed systems exist, most systems used in water treatment plants combine chlorine gas (some use liquid sodium hypochlorite) with sodium chlorite (either solid or liquid). A chlorine dioxide solution is then fed at the point of application. Although chlorine dioxide feed systems are often a hybrid of gas and liquid (or solid), this discussion is included in the gas feed section of this book because the chlorine gas is commonly the controlling factor in this system. 

Many water treatment operators consider liquid chemicals easy to feed and handle. Chemical suppliers deliver the chemicals in sealed containers, and the feed and delivery systems are contained. Accurate feed is assured when using properly sized, calibrated, and maintained chemical metering pumps and control systems. Liquids also mix easily into the process water stream. Table 7-1 hsts some of the more common liquid chemicals used in water treatment. In addition to these, there are many liquid polyelectrolytes sometimes used in coagulation and filtration. They are not listed in the table because their properties vary depending on the specific product. 

The destruction of sarin (GB) in the EDS using aqueous MEA (45 percent) as the treatment chemical produces an organic-rich neutralent stream, as described in Chapter 2. The postireatment of this neutralent stream is the focus of this report, but there are also other liquid waste streams that must be dealt with. The other streams result from the riusing of the EDS chamber with water after each use to remove residual MEA and soUd residues and the cleaning to remove other solid and liquid residues. These waste streams must also be prepared for ultimate disposal unless their compositions meet the feed requirements for an on-site treatment works. The diverse nature of these waste streams is illustrated in Table C-1. 

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