Wastewater reaching the treatment facility comes primarily from households sources [but] some [also] comes from industrial sources. The facility therefore handles a mixture of wastewater from these two sources, where industrial wastewater constitutes about 15% of all wastewater at the facility.
According to municipal ordinances, industrial plants are required to comply with sewage quality as specified by law so that they can discharge their wastewater into the municipal collection system and from there to the treatment facility.
The purpose of this law is to prevent discharge of materials into the sewage system that may harm sewage carrier systems, biological processes used in treating wastes, effluent quality and the quality of sludge intended for reclamation.
The treatment facility has a staff given the task of monitoring industrial wastewater, which performs routine inspections at plants connected with municipal sewage systems. The staff samples the wastewater and verifies that the plants indeed comply with standards as required from them.
Wastewater specimens are sent to the facility's laboratory for testing for purposes of determining concentrations of contaminants, [for purposes of] monitoring, archiving and preparing test reports for the plants and outside bodies and for treating sources of contamination.
The association does not have authority to enforce municipal ordinances and state laws. This enforcement is handled instead by local authorities and the Ministry of Environmental Protection, which of course may use the laboratory findings to establish their claims.
Deviations repeatedly occur in COD, total solids, chlorides and pH values at many plants.
The most problematic parameters from the standpoint of treatment facility processes are oils of various types, COD and metals.
It is highly probable that the phenomenon of ‘sludge swelling' is caused due to the binding of sludge particles with oils. This phenomenon severely impacts the functioning of the activated sludge process and causes changes in the rate of treatment and reduction in the quality of facility effluents.
Excess concentrations of heavy metals are also found at various plants. Certain metals may harm various stages of the biological treatment processes based on microbial activity. However, it should be emphasized that these metals do not reach the effluents but are instead removed in the sludge.
Deviations in pH values of the wastewater have a negative impact primarily on carrier lines.
From the standpoint of the use of effluents for irrigation, the most problematic parameters are salinity (chlorides) and boron that significantly reduce the variety of crops that can be watered using facility effluents. It should be emphasized that the biological treatment facility does not remove salts and boron so that they therefore must be treated at the source.
Following the establishment of water companies at many local authorities, supervision of industrial plants and enforcement has been transferred to their responsibility. New regulations have been published for the quality of industrial wastewater that may be discharged into public sewage systems and treatment plants. The water companies are the bodies that must enforce the new regulations in their jurisdictions.