INDUSTRY & BUSINESS
Polymer use for waste treatment grows Organic flocculants challenge inorganics with cost savings, better performance The nation's growing water pollution problem is sparking increasing interest in organic polymeric flocculants for sewage treatment. Several companies are now actively promoting such polymers, which can materially improve the operating efficiency and capacity of many existing municipal waste treatment plants. Moreover, the polymers are effective without capital investment and at reasonable c o s t about $7.00 per million gallons for use in primary treatment. Dow Chemical, one of the pioneers, has spent several million dollars in developing such polymers over the past seven years. The company has had them on the market since 1964. More
recent entries include Nalco Chemical, Rohm and Haas, and Hercules. These high-molecular-weight, watersoluble polymers can be used in several ways in waste treatment plants. For instance, they can replace inorganic flocculants such as ferric chloride and lime, commonly used in sludge dewatering and filtering. Also, they can boost the performance of primary treatment units by as much as 50%. Theoretically, the market for these polymeric flocculants could exceed $20 million per year. Nobody is predicting it will approach this. But then nobody is predicting just what it will reach. According to Dow, these polymers could play a critical role in the nation's battle with increasing water pollution. For instance, waters such as Lake Erie and the Hudson River are seriously polluted. The southern end of Lake Michigan is also in poor shape. And scores of other waterways are being dangerously polluted with industrial and municipal wastes. Although
FILTRATION. In this municipal treatment plant, polymeric flocculants have improved processes such as dewatering waste sludge prior to incineration
many new treatment plants are planned, it will be several years before enough capacity is on stream to 'substantially reduce overall pollution. Primary treatment. Today, waste from about 30 million people in the U.S. is receiving only primary treatment or primary treatment plus inadequate secondary treatment. It is here that polymeric flocculants could find their greatest use. Primary treatment of raw sewage, which is just a settling process to lower suspended solids, typically removes about 3 5 % of the biological oxygen demand (BOD) of a sewage input. If this settling is augmented with a polymeric flocculant, up to 60% BOD is removed. This is not as good as the 80% or more removed with proper secondary treatment, but the improvement to 60% can be done immediately in existing facilities at about one tenth the cost of building and running secondary treatment plants. Dow calls it "instant abatement." These polymeric flocculants have not been accepted as readily as they might, Dow says, because of the great stress in pollution circles on building new treatment plants. Also, financially hard-pressed municipalities often won't spare extra operating funds for existing plants. Increasing amounts of federal and state money are becoming available to help finance new plants as the nation begins to awaken to the severity of its water pollution problems. This year, $150 million of federal money will go in matching funds for new municipal plants, up from $100 million last year. On the state level, the New York legislature, for instance, has recently appropriated $300 million for construction grants. Federal and state funds are not available on this scale to upgrade the operation and maintenance of existing plants. Several mechanisms. Polymeric flocculants work by several mechanisms. Most of the polymers used in sewage plants are either cationic or anionic. Sewage particles in suspension are normally negatively charged. Cationic flocculants therefore work mainly by charge neutralization. Anionic polymers work 'by a bridging mechanism. These polymer molecules are long and linear and have many charged sites. Each is adsorbed on the surface of a number of sewage particles. Dow's polymeric flocculants are
known as Puriflocs. Purifloc C-31, a cationic, has found use for sludge dewatering, while Purifloc A-21, an anionic, is used in primary treatment. In sludge dewatering, Purifloc C-31 shows many advantages over the ferric chloride and lime it is replacing. It saves as much as 30% on chemical costs and reduces labor and maintenance costs. There is less of it to handle—about 20 pounds per ton of dry sludge solids compared with about 300 pounds of the inorganics. It is not as corrosive as ferric chloride. Also, it does not form scale as lime does. It increases the capacity of treatment units such as clarifiers, digesters, and filters. And the sludge produced with C-31 gives no slagging problems when incinerated, since it contains little inorganic material. Dow says about 60 plants are now using C-31 for dewatering. However, progress for A-21 in primary treatment has been slower. Here, a chemical is being used where usually none was used before. Hence, extra cost is involved. This has helped keep acceptance down to about 10 plants. For primary treatment, the flocculant is added at about 1 p.p.m. on the sewage input. Results vary widely from plant to plant and with the type of sewage. Suspended solids removal is typically increased from about 4 5 % (with no flocculant) to 70% when the polymeric flocculant is used. BOD removal jumps from about 3 5 % to as much as 60% or more. Such advantages accrue even when secondary treatment is available. In tests this spring at Grand Rapids, Mich., Purifloc A-21 boosted the BOD removal of a secondary treatment plant from 82 to 8 8 % . Nalco has been marketing two polymeric flocculants, Nalcolyte 603 and 675, for sewage treatment since early this year. So far the main effort has been in filtering and dewatering. The company says it has made "excellent gains" in this area. Rohm and Haas has been selling both a cationic and an anionic polymeric flocculant for sewage use since August 1965. Known as Primafloc C-7 and Primafloc A-10, they are mainly used for sludge concentration
"We have reached something of a turning point in chemicals . . . as we approach a consumer economy and the realization of its complexities. We have reached the point where only innovative and sophisticated market research is going to make a chemical company successful and profitable in the future," Celanese Corp/s Frank Pizzitola said at the fall meeting of the Chemical Marketing Research Association. There was little need for speaker Pizzitola (who is group vice president-chemicals at Celanese) to fear the soporific effects of what he described as the "immoral commodiousness of the theater chairs" in the cinema at the Greenbrier in White Sulphur Springs, W.Va. He got instant attention when he told his listeners that marketing research is one of the most sophisticated sciences of the U.S. industrial economy, "the most important of all industrial and business skills." Chemical companies, Mr. Pizzitola says (and particularly those in bulk commodities ), must come to know the needs of their customers, and their customers* customers, far better than they have in the past. The chemical company today is faced with a new customer, the American family. Mr.
and dewatering. The company is also
Pizzitola
developing an anionic specifically for use in primary treatment. But it does not yet have such a polymer on the market. Among other companies in the field, Hercules is now offering two polymeric flocculants for sewage treatment. Reten A-l, an anionic compound, is for primary treatment. Reten 210 is cationic and designed for dewatering, filtering, and sludge thickening.
through Celanese's interest in coatings, a field in which "we want to know all we can about the needs of our customers, our customers' customers, and their customers, and we want to know how all these needs are related, influenced, and motivated." One of the chief industrial markets of Celanese's coatings company (it acquired Devoe & Raynolds two years ago) is Detroit. Through its coatings company, Celanese has been able to
Selective Oxidation Processes
Frank Pizzitola Recommendations, not just facts
Chemicals enter purchase economy
exemplified
this
change
SELECTIVE OXIDATION PROCESSES Do oxidation processes, products, and mechanisms interest you? "Selective Oxidation Processes" ADVANCES IN CHEMISTRY SERIES No. 51 surveys a number of processes and details research on improving the range, selectivity, and mechanisms of such processes. The book includes discussions of hydroxylating selected aromatics and olefins, pyrolysis of isobutylene—all of these by vapor phase processes. Among liquid phase processes are three general methods for oxidizing aromatics, sulfur dioxide as oxidant for a number of products, use of nitrogen dioxide catalyzed by selenium dioxide, and ozone as a selective oxidant. The last chapter is a broad survey of carbanion oxidation. The book is based on a symposium sponsored by the ACS Division of Petroleum Chemistry. 177 pages with index Cloth bound (1965) $6.50 Order from Special Issues Sales American Chemical Society 1155 Sixteenth St., N.W. Washington, D. C. 20036 OCT. 10, 1966 C&EN
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