One of the most common tests for the determination of strength and organic content of wastewater is the Biochemical Oxygen Demand (BOD). The capital of Cyprus, Nicosia has upgraded its wastewater treatment plant during the 2000s, providing a significant improvement in BOD and TSS treatment performances. These performances are tested by the data collected from 1994 until 2005 by using one-way ANOVA and least significant difference (LSD) tests. The tests showed significant difference (p<0.05) in the means of the samples investigated before and after the upgrading of the treatment plant. Experimental results showed that the installation of innovative anaerobic lagoons was able to reduce the BOD and TSS concentrations to desirable values that fell within the discharge limits of national and international effluent standards. However, the limits for the reuse of effluent for irrigation purposes require more improvement on the treatment technology. The significant improvement in BOD removal percentages increased the BOD removal performance up to 93%, whereas the TSS removal performance increased to 84%. (C) 2009 Elsevier B.V. All rights reserved.