258 



Sewage treatment reduces and alters the impact of municipal waste 

 on the environment. Primary treatment with chlorination removes 

 part of the decomposable organic material, removes nearly all of the 

 settleable and suspended solids, and almost eliminates the possibility 

 of pathogens in the effluent. Secondary treatment can almost eliminate 

 decomposable organic material, and some special processes can elim- 

 inate certain dissolved salts. About half the municipal wastes dis- 

 charged to estuarine waters receives secondary treatment, with the 

 most extensive use of secondary treatment being in the Chesapeake 

 Bay estuarine region. 



INDUSTRIAL WASTES 



Associated with the major metropolitan developments are large 

 numbers of industrial complexes with their attendant waste products. 

 Many of these wastes, especially from the chemical and petroleum in- 

 dustries, are so complicated that it is difficult both to identify them and 

 to assess their effects on the receiving streams. 



Table IV.3.2 gives a summary of the major manufacturing indus- 

 tries in the estuarine zone. Table IV.5.6 presents the basic character- 

 istics of wastes from each major industrial category. Table IV.5.7 

 and table IV.5.8 show the waste discharges and levels of waste treat- 

 ment associated with this industrial development. 



Table IV. 5. 6. — Pollution characteristics of industrial waste 



Origin of major waatea 



Powerplant, stack washing, leaching from 

 ashes, lubrication and hydraulic oil spil- 

 lage, surface cleaning, treating and 

 painting, plating operations, trimming 

 and buffing operations, milling with cut- 

 ting oils. Repair and rework operations. 



Washing of raw products, slaughtering, 

 separation of skins, peels, pits, scales, 

 feathers and other inedible fractions of 

 crude products, rendering of fats, blanch- 

 ing, cooking operation, curing and pick- 

 ling operations, byproducts of too little 

 value to market, spills, floor and equip- 

 ment cleaning, diffusion extraction opera- 

 tion, wet grinding operations, steep tank 

 liquors, still bottoms and cooling water. 



Mainly dry operations, some incidental 

 cleanup operations. 



Wool scouring, desizing operations, clean- 

 ing, dyeing and bleaching. 



Dry operations. 



Type of industry 

 Ordnance and accessories. 



Food and kindred products. 



Tobacco manufactures. 

 Textile mUl products.. 



Apparel and other finished prod- 

 ucts made from fabrics and 

 similar materials. 



Lumber and wood products, ex- 

 cept furniture. 



Furniture and fixtures. 



Leaching of logs being floated to mills and 

 held in ponds for milling. Sawdust is 

 potentially a heavy polluting agent if 

 disposed so that it is washed into surface 

 waters by storm runoff or if stored so that 

 leachate reaches surface waters. Preserva- 

 tives and glues. 



Water curtain utilized to pick up waste 

 from varnishing, painting, and finishing 

 operations. 



J 



