1900 1950 2000

1900 1950 2000

FIGURE 4.10 Schematic drawing showing effluent standards requirements for disposal of municipal sewage to unconfined marine waters (where access to open ocean is feasible and DO is not a significant parameter).

An economic analysis is needed to compare costs for the submarine outfall plus floatables removal, versus a short outfall with complete treatment.

Disposal to open ocean waters also can greatly simplify disposal of industrial wastewaters, which may contain numerous substance (such as salt, degradable organics, inorganic chemicals, etc.) that cannot be discharged to inland waterways without treatment to remove substances that impair confined water quality but that need not be removed for disposal to open seawater105.

Buffer Area Requirements around Treatment/Pumping Plants

Recommendations that are considered appropriate for DCs are given in a paper by R. Bradley24. His recommendations are summarized in Figure 4.11.

Regional Water Pollution Control

Few DCs have yet developed regional water pollution control systems, which can cover the needs for a group of municipalities, but beginning efforts to do this are the Samutprakarn regional system in Thailand107, the proposed regional plan for Abidjan in the Ivory Coast67, and the regional systems for the coastal provinces in north China163.


Management of industrial wastewaters is a very complex subject because of the great variety (ever increasing) of pollutant constituents contained in these wastew-aters. One way or another, by treatment, by use of cleaner production technology, or by point source control, the levels of these pollutants must be controlled to reduce concentration to levels acceptable to receiving waters. Fortunately, U.S. EPA, with its ample financial resources, has been able to produce a series of excellent manuals, one for each type of industry (now available on the Internet), which give excellent basic data for each industry including quantification of all raw materials utilized, the steps involved in manufacture, and the various types of wastes produced by each step, including needs for treatment of these either singularly or combined. The online manuals include illustrative schematic drawings. These basic data are equally useful for IC and DC purposes. The U.S. EPA manuals include a final chapter which includes environmental standards applicable in the U.S. together with the matching treatment requirements. Unfortunately, these manuals do not include an additional chapter on standards and matching treatment requirements that are appropriate for DCs. It would be greatly helpful to the DCs if U.S. EPA would do this.

The job of the DC designer is to devise environmental standards and matching treatment requirements that are appropriate for the particular DC. The target for DCs should be point B in Figure 4.3 of the Introduction section, not the point C

FIGURE 4.11 Recommended guidelines for buffer zones.

1940 1950 1960 1970 1980 1985

FIGURE 4.12 Schematic drawing illustrating requirements in U.S. over Past 50 years for removal of oil from refinery effluents.

1940 1950 1960 1970 1980 1985

FIGURE 4.12 Schematic drawing illustrating requirements in U.S. over Past 50 years for removal of oil from refinery effluents.

target used in the ICs. An example of this approach is illustrated here from ADB sources112 for petroleum refinery wastewaters, as shown here in Figures 4.12 and 4.13. Figures 4.14 show recommendations for control of industrial wastes disposal of by infiltration into groundwaters for the parameter of total dissolved solids (TDS).

Discharge into Municipal Sewerage Systems (MSSs)

Box 4.3 describes preparation of a municipal ordinance that encourages industries to make use of the MSS (municipal sewerage system), which can greatly assist in financing the overall MSS, but with a system of controls that protects the MSS and the receiving water environment. The salient control items are the following:

• Restrictions to prohibit discharge into the MSS of any industrial wastewaters that cannot be received by the municipal system because of hazards of damage to the system, or to receiving waters or land areas to which the STP effluent is discharged

• In-house pretreatment by industries for removing unacceptable constituents from industrial wastewaters so effluents will be acceptable for discharge to MSS (or directly to the environment)

Notes: Drawing based essentially on experience in California where requirements are imposed by California State Regional Water Pollution Control Boards, as well as by USEPA. Recommendation for DCs: Gravity/API separator only, with due attention to O&M. Where more is needed for eco-protection, supplement with prolonged ponding (several days).

(C) Biological Stabilization

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