Failure Analysis of Biological Treatment Units Under Shock Loads of Rubber Industry Wastewater Containing Emerging Pollutants: Case Study

This paper presents the results of a survey of the designed biological wastewater treatment facilities of an enterprise specializing in the production of rubber products. The aim of the study was to assess the efficiency of wastewater treatment systems under the conditions of a salvo discharge of industrial effluents that differ in composition from domestic wastewater. The analysis covered the parameters of water supply, water disposal, and wastewater characteristics at various stages of treatment. Three samples were taken: after washing the premises (WW1), at the inlet to the treatment facility (WW2), and at the outlet after treatment (WW3). Experimental assessment of the purification efficiency for key pollutants showed a high degree of removal of surfactants (91.2%), oil products (84.4%), and COD (63.4%). However, phosphorus–phosphate turned out to be significantly higher than the norm—2.32 mg/L with an acceptable level of 0.2 mg/L—which corresponds to an excess of 11.6 times. A low degree of ammonium nitrogen removal was also revealed—62%. Calculations showed a critically high ratio of COD/BOD5 = 5.1 with the recommended <2.6, which indicates a small share of biodegradable substances and the need to implement physical and chemical treatment methods. The absence of the characteristic smell of household wastewater and the presence of black inorganic sediment confirm the toxicity of emerging pollutants for activated sludge. It is concluded that the installed biological treatment system cannot cope with the salvo loads of industrial wastewater. Optimization measures are proposed: preliminary local treatment, dosed feed, and a separate treatment system.