The performance of one-step UASB reactors treating fish processing wastewater of different lipid levels was determined using artificially generated influent simulating that of the canning of sardines and tuna. The organic loading rates (OLR) and the hydraulic retention times (HRT) were 5–8 g COD.L⁻¹.d⁻¹ and 11–12 hours, respectively. In treating a wastewater that contains 3–4 g.L⁻¹ total COD of which 5–9% was lipids, the COD removal and conversion to methane were ca.78% and 61%, respectively. In treating a wastewater with a higher lipid content (ca. 47% of the total COD), the total COD removed and converted to methane were 92% and 47%, respectively. A considerable part of the influent total COD was removed via adsorption on reactor surfaces and sludge particles. The adsorption of lipids on sludge particles threatens the stability of the UASB operation. Thus, the performance of a first-step UASB reactor in removing suspended solids (SS) from a “high-lipid” wastewater was also determined in this study.

The widespread presence of heavy metals in drinking water sources arises as a major health concern, particularly in developing countries. The development of low-cost and reliable detection techniques is identified as a societal need to provide affordable water quality control. Herein, a bismuth film-coated gold ultramicroelectrode array (BF-UMEA) was used for the detection of Pb(II) and Cd(II) in water samples via square wave anodic stripping voltammetry (SWASV). Experimental parameters such as deposition time, Bi(III) concentration, acetate buffer concentration, pH, square wave frequency, amplitude, and step potential were all varied to determine their effects on the current peak intensities of the target metal ions. Ten-fold excess in the concentration of interferences was found to cause a decrease in the stripping peak areas of Cd(II) and Pb(II) in the following order of magnitude: benzene < NaCl < Ni(II) < Cu(II). Using Box–Behnken design, the optimum SWASV parameters that provided maximum current peak areas were 14.76 Hz (frequency), 50.10 mV (amplitude), and 8.76 mV (step potential). The limits of detection of the as-prepared BF-UMEA were 5 and 7 µg L⁻¹ for Pb(II) and Cd(II), respectively. These results demonstrate the potential use of a BF-UMEA in SWASV for the trace quantification of Pb(II) and Cd(II) in water samples.