Discharge to Drain or Sewer

Perhaps the most common disposal method for RO reject is simply sending it down the drain to sewer or waste treatment. However, discharging in this manner may actually not be a simple as it sounds. There are regulations and permits that may be required that limit discharge of specific contaminants. 

Discharge to a sewer or publicly owned treatment system (POTW) is not as regulated as discharge to a natural watershed. Most jurisdictions do not require permits and regulate only pH. However, there may be an up-charge for high concentrations of certain contaminants such as chlorides. 

Discharge to a natural watershed generally requires a permit that must be periodically renewed. Permit requirements vary greatly from location to 

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As discussed in Chapter 17, legislative controls including stringent consent conditions are applied in the UK to all discharges to specified sewers. (Discharge of effluent to surface water drains is prohibited.) Limits, or even total prohibitions, are placed upon certain chemicals to avoid... 

At the end of the cleaning phase, the system should be drained and thoroughly flushed out to remove all traces of chemical cleaner, iron, and other foulant materials. Local regulations, or simple good practice, may dictate that pH neutralization or other pretreatment is required before the water is permitted to be discharged to foul sewer. 

A. Account for wastewater. On many sites, significant quantities of both clean and contaminated water are discharged to sewers or to a watercourse. In many cases, this wastewater has environmental implications and incurs treatment costs. In addition, wastewater may wash out valuable unused raw materials from the process areas. Therefore, it is extremely important to know how much wastewater is going down the drain and what the wastewater contains. The wastewater flow, from each unit operahon as well as from the entire process, must be quanhfied, sampled, and analyzed. 

Diked areas around refinery storage tanks are frequently provided with storm drains discharging into the trunk sewer. An overflow as the result of an overfilled or ruptured tank could discharge large quantities of oil to the refinery sewer and would ultimately overload the separating facilities. To prevent this and to allow recovery of the oil within the diked area, it is common practice to provide some type of valve arrangement to isolate the storm drains in tank fields from the trunk sewer. 

It is usually advisable to blind or block an unused branch or lateral where it enters an active sewer. When welding is in progress near open catch basins, the usual procedure is to seal the catch-basin lid with sandbags or place a tarpaulin with a cover of sand over the lid. Similar precautions should be taken near floor drains or other open drains that may be discharging flammable vapors. 

Only a few years ago, it was common practice to dispose of many laboratory wastes down the drain. Today, the indiscriminate disposal to the sanitary sewer of laboratory chemicals is not acceptable. Most laboratory drain systems are connected to sanitary sewer systems, and their effluent will eventually go to a sewage treatment plant. Some chemicals can interfere with the proper functioning of sewage treatment facilities or affect particularly sensitive bodies of water into which the chemical is discharged. In the laboratory drain system itself, some chemicals can create hazards of fire, explosion, or local air pollution. Others can corrode the drain system. 

The installation of a capture box will be required for those work place layouts where the floor drain is located in the same room as the sterilizer or in a room where workers are normally present. A capture box is a piece of equipment that totally encloses the floor drain where the discharge from the sterilizer is pumped. The capture box is to be vented directly to a non-recirculating or dedicated ventilation system. Sufficient air intake should be allowed at the bottom of the box to handle the volume of air that is ventilated from the top of the box. The capture box can be made of metal, plastic, wood or other equivalent material. The box is intended to reduce levels of EtO discharged into the work room atmosphere. The use of a capture box is not required if (1) The vacuum pump discharge floor drain is located in a well ventilated equipment or other room where workers are not normally present or (2) the water sealed vacuum pump discharges directly to a closed sealed sewer line (check local plumbing codes). 

By adding a trickling water supply and drain, Q3, to the drag-out tank, the application of Kushner s concept can be extended to other metal finishing processes that may not be amenable to full reuse but can allow partial reuse. Figure 9.3 depicts the partial reuse scheme. The trickle concentrate can also be batch treated in a small volume on-site, recycled at a central facility, or mixed with Qx, for discharge, if the combined metal content is below sewer discharge standards. 

Fire not only poses a risk to life and property it also has a significant impact on the environment. Environmental damage from fires can be both short and long term and, in the case of poiiutants from fires affecting groundwater supplies, may persist for decades or even longer. Rivers, sewers, culverts, drains, water distribution systems and other services all present routes for the conveyance of pollutants off-site and the effects of a discharge may be evident some distance away. 

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