Waste treatment and disposal aspects to development of California's pulp and paper resources ... : a cooperative study.

  • California. State Water Quality Control Board.
Date:
1957
Catalogue details

Licence: Public Domain Mark

Credit: Waste treatment and disposal aspects to development of California's pulp and paper resources ... : a cooperative study. Source: Wellcome Collection.

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    multiply more rapidly than other forms and deplete the oxygen supply. The oxygen concentration may be lowered sufficiently to cause serious stress to the higher forms which normally feed on the bacteria. This results in accelerating the unbalance between bacteria and predators and, as the ratio of bacteria to predators increases, the oxygen supply decreases. In some streams where reaeration is not sufficient to supply the increased need for oxygen and the bac- terial food supply is overabundant, the dissolved oxygen may drop to zero. If such a condition exists for an extended period of time, the anaerobic bacteria previously mentioned will attack the remaining food. Unlike the aerobic metabolic process, which utilizes the waste to ultimate destruction as carbon dioxide and water, the anaerobes only partially utilize this food supply, yielding organic acids and gaseous end products. These compounds result in the universally known malodorous characteristics of a polluted stream. While the process described above is being enacted in the stream, there is concurrent with it a recovery process whereby the oxygen supply is being replen- ished. Oxygen from the atmosphere immediately above the water surface diffuses through this interface and is dissolved in the stream. The capability of the stream to absorb and hold oxygen is dependent on its tem- perature, depth, velocity, and turbulence. Cold, fast- running, turbulent streams of high volume seldom are deficient in oxygen and exhibit high waste-assimilating capacities and quick recovery from effects of waste discharge. It is essential to the health of the stream that the waste assimilation process (oxygen utilization) be balanced by the recovery process (reaeration) in such a way that the dissolved oxygen does not fall below levels which would cause stress to the higher forms, and that the oxygen deficit is replenished in a reason- able downstream flowing time. The BOD test offers a means of predicting the amount of oxygen required by the stream organisms in utilizing the influent organic matter. Knowing the oxygen demand of the waste and the rheology of the stream (its depth, velocity, turbulence, surface area, and quantity of flow), it is possible to determine how much waste material may be put safely into the stream. The BOD test provides for the microbiological utilization of a known amount of organic waste in a specific time interval using standard nutritional fac- tors simulating stream conditions. The initial dis- solved oxygen is determined and compared to that remaining after the standard incubation time of five days. The amount of oxygen required for a specific amount of waste is then easily calculated. Through national standardization of analytical methods, the BOD test in the hands of a competent analyst offers an excellent means of grading organic wastes accord- ing to their pollutional potential. An excellent and more detailed discussion of oxygen assets of receiv- 52 ing bodies, together with a graphical representation of the dissolved oxygen profile and its quantitative esti- mation based on the BOD reaction, can be found in Phelps’ Stream Sanitation (25). Solids Concentration—The terms used in describ- ing solids are as follows: . Total solids . Dissolved solids . Total suspended solids . Volatile solids . Mineral solids or ash . Settleable solids D> OR CoD eH Total Solids—These include all solid matters pres- ent in the waste. They are generally broadly classed as dissolved, total suspended, and settleable sus- pended. Dissolved Solids—These include organic and in- organic compounds which are in true solution. They are important in consideration of the industrial waste since it is the organic portion of the dissolved solids which comprises the BOD. Other organic portions, particularly lignin, which is not readily metabolized by microorganisms, contribute to the color of the waste. Inorganie dissolved solids are not generally im- portant except that certain concentrations of inor- ganic solids are necessary for bacterial growth. Ex- treme concentrations of some inorganic solids may be toxic or may otherwise render water undesirable for some specific uses, such as industrial process water, irrigation, and domestic supply. Total Suspended Solids—These include _ those solids of colloidal or larger dimensions, suspended in water. They contribute to the turbidity of the waste. They may act as nuclei for adsorption of other par- ticles, become coagulated and settle to the stream bot- tom. This phenomenon is dependent on the chemical composition and rheology of the receiving body as well as the stability of the colloidal particles. Volatile Solids—These include the solid material, either dissolved or suspended, which will volatilize at a temperature of 600° C or less. These solids may be considered totally organic. Mineral Solids or Ash—These include the inor- ganic content of the dissolved, suspended, or total solids fractions. of the total suspended solids which settle under quies- cent conditions in an arbitrarily fixed time. Toxicity—Most chemicals are toxic to aquatic life if present in water at sufficient concentration. Since kraft mills discharge a very dilute effluent, the only constituents of concern are those which are toxic in very high dilutions. Research by the National Coun- cil for Stream Improvement, the Institute of Paper Chemistry, Oregon State College, and others has indi- cated that kraft effluent diluted 20:1 by stream water is a safe environment for the aquatic life tested (26,