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Increased use of engineered nanoparticles (ENPs) has resulted in their entry into municipal wastewater treatment plants (WWTPs) as their final sinks. However, the adverse impact of ENPs on the bacterial activity in the activated sludge WWTPs is not yet well understood, despite their increased release into such systems. In this study, the impacts on WWTPS associated with the disposal of zinc oxide (ZnO) ENPs was investigated using a simulated WWTP developed as per the prescribed Organization for Economic Co-operation and Development (OECD 303A) specifications. Analyses were done to determine zinc concentrations at various stages of the setup, mainly in the raw wastewater and treated effluent, using inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained indicated low levels of zinc residue (about 50-200 µg/L) in the treated effluent compared to relatively high concentrations of Zn in the sludge (about 3 000 mg/kg). Results reported herein imply precipitation of ZnO ENPs during wastewater treatment processes and hence its high levels in the sludge. The presence of solid Zn in the sludge was determined using X-ray diffraction spectroscopy (XRD). Overall, no significant impact of ZnO ENPs on the performance of the simulated WWTP was observed, in terms of the removal levels of chemical oxygen demand (COD) during the treatment process

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Introduction: The specific physiological capacity of marine organisms, including seaweeds, to survive in extreme environmental conditions is associated to the production of secondary metabolites. Seaweeds are known as powerful source of a broad range of bioactive compounds. Objective: The aim of this study was to investigate the phytocompounds and chemical elements present in eight species of seaweeds which occur around Inhaca Island, Mozambique. Specifically, Halimeda cuneata, Pseudorhizoclonium africanum, Pseudocodium devriesii, Dictyota suhrii, Gracilaria salicornia, Hypnea rosea, Laurencia natalensis and Jania adhaerens. Methods: For phytocompounds and chemical elements screening, seaweeds samples were dried, ground to powder and extracted using methanol as solvent. The analyses were performed using GC-MS analysis, Energy Dispersive X-ray Fluorescence, and colorimetric protocols for phytocompound analysis. Results: A total of 82 phytocompounds were identified. Phytol and Z-8-Methyl-9-tetradecenoic were present in all samples analysed, while Cetene, 9-Octadecenoic acid (Z)-methyl ester, Desmoterol, Octadecanoic acid, and Oleic acid were the less common phytocompound identified. Campesterol, gama-Sitoesterol, Cholest-5-en-ol, 24-propylidene-(3.beta) are phytosterols only identified in green seaweeds. The concentration of chemical elements among the seaweeds species was different. However, Ca, Cl and K were presented in high concentration in some of the seaweeds analysed. Conclusion: Overall, the seaweeds analysed in this study, seems to be good candidate for further biotechnological application and deserve further investigation. Keywords: seaweeds, methanolic extracts, phytocompounds, minerals, Inhaca Island.

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Due to the toxicity of trace metals and the propensity of fishes to bioaccumulate metals in their tissues, we investigated the concentrations of arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), mercury (Hg), and zinc (Zn) in the muscles of tilapia (Oreochromis mossambicus) and catfish (Chrysichthys nigrodidatatus) collected from open markets in Mozambique. Fe and Hg were the most and least bioaccumulated metals in the fishes, respectively. One-way ANOVA showed significant differences between sites for the analytes. Furthermore, we estimated the possible health risks (estimated daily intake (EDI), target hazard quotient (THQ), and maximum allowable consumption rate (CRlim)) associated with fish consumption. The concentrations of As, Cd, and Pb exceeded the recommended maximum permissible limits (MPL) in fish samples, ranging between 5.65 – 12.7, 1.05 – 12.9, and 1.88 – 6.45 mgkg-1, respectively, whereas values lower than MPL viz. 5.25 – 18.9, ND – 0.033, and 30.8 – 52.3 mgkg-1 were observed for Cu, Hg, and Zn, respectively. Similarly, the EDI (mgkg-1day-1) were below the provisional tolerable daily intake (PTDI) with decreasing order: Fe >Zn >Cu >As >Cd >Pb>Hg. However, the THQ (mg kg-1) was slightly > 1 for As and Cd in some samples. Moreover, the CRlim (kg day-1) showed a decreasing order of Hg >Fe >Zn >Pb> Cu >Cd >As. Generally, consumers are susceptible to health hazards associated with As and Cd. Hence, regular toxicological monitoring of the fishes from the study area is imperative.