Treated Water Quality and Interrelationships Between Wastewater Parameters at WWTP of Batna City (Algeria)

Treated wastewater, both in quantity and quality, represents a promising resource and valuable substitution for mitigating freshwater overuse and degradation. However, this non-conventional resource can be safely reused only through appropriate wastewater treatment process. Various factors control the variation in the effectiveness of wastewater treatment plants (WWTPs). This study aimed to characterize wastewater quality and interrelationships between wastewater physicochemical parameters (WWPCP) to assess the effectiveness of WWTP’s performance. Using multiyear datasets of biochemical oxygen demand (BOD5), total suspended solids (TSS) and nitrate (NO3) measured at the WWTP of Batna City in NE Algeria, water quality was assessed in both influents and effluents. Person correlation tests examined interrelationships between these WWPCP at inlet and outlet of the WWTP. The physicochemical analysis of raw and treated wastewater showed remarkable temporal variations in values of the studied water characteristics. In raw wastewater, BOD5 ranged between 52 and 780 mg/L (min–max), while it achieved 0.8–142 mg/L in treated wastewater. TSS varied from 22 to 1784 mg/L in the influent and from 4 to 284 mg/L in the effluent. The decomposed nitrogen showed high values of NO3, where it ranged between 0 and 5.62 mg/L in the influent and 0 and 5.94 mg/L in the effluent. The high records of TSS, BOD5, and NO3 are indicators of an increasing water pollution load that can be explained by the urban sprawl and demographic increase. Sometimes, the WWTP dysfunction induces the increase in these parameters in the effluent. While the influents were highly contaminated, averaged values of the surveyed parameters exceed the international standards in the effluent during the last years of the survey. Correlations among wastewater parameters showed highly interrelationships where parameters influenced each other. These findings help to determine the quality of treatment process and can predict the malfunction and propose solution with ease for better WWTP management.