Posttreatment of olive mill wastewater by immobilized TiO2 photocatalysis

A photocatalytic reactor with UV/TiO2 was used for the post-treatment of olive mill wastewater after anaerobic digestion. A factorial experimental design was adopted to determine the statistical significance of each parameter tested, namely initial COD, pH, treatment time and recirculation flow, and possible interactions, in three response variables: phenols, colour, and COD removals. Removal efficiencies of 90.8 ± 2.7 %, 79.3 ± 1.9 %, and 50.3 ± 6.3 % were obtained for total phenols (TPh), colour, and COD, respectively. TPh and colour were almost completely removed after 24 h of treatment, while the COD removal was partial. Because increasing the treatment time is economically unfeasible a recirculation to the anaerobic reactor should be considered. Regarding the most significant variables, the TPh removal efficiency is dependent of the initial COD concentration; the colour removal efficiency decreased with increasing COD concentration and pH; and, the COD removal efficiency is directly linked with the treatment time. The interaction between the initial COD and treatment time affect negatively the response variables tested because of the inactivation of some active sites of the TiO2 paper.The Portuguese Science Foundation (FCT) and the European Social Fund (ESF, POPH-QREN) gave financial support through the Post-Doctoral grant attributed to Jose Carlos Costa (SFRH/BDP/48 962/2008) and through the project PTDC/ENR/69 755/2006. The authors thank Dr. M.N. Pons and Dr. O. Zahraa the offer of the reactor and Mr Ing. J. Dussaud from Alstrohm (Pont-Eveque, France) for the TiO2 paper

Simultaneous recovery of ammonium and phosphate from simulated treated wastewater effluents by activated calcium and magnesium zeolites

BACKGROUND In this study a sodium zeolite synthesized from coal fly ash (NaP1-NA) was modified to calcium and magnesium forms (Ze-Ca, Ze-Mg) as sorbent materials for simultaneous recovery of ammonium and phosphate from simulated treated wastewater effluents. RESULTS Increasing the temperature during the modification step to magnesium form improved the zeolite conversion. The maximum sorption capacities obtained were 123.1±9.1 mg NH4 g-1 and 119.5±7.5 mg PO4 g-1 in an ammonium/phosphate binary system for Ze-Ca, while 55.2±2.4/ 60.5 ±14.1 and 32.3±4.4/ 23.9±3.4 were obtained for Ze-Mg1 and Ze-Mg2, respectively. The sorption process is faster for Ze-Mg zeolites and the sorption mechanism that controls the overall process, for both zeolites, is diffusion into the particle according to the HPDM and SPM models. CONCLUSIONS Salt modification improved the performance of zeolites towards phosphate sorption. The sorption mechanism involves both ammonium exchange to the Mg and Ca ions, and precipitation of Ca and Mg phosphates or mixed ammonium-magnesium phosphate minerals such as brushite (CaHPO4.H2O) and struvite (MgNH4PO4). © 2017 Society of Chemical IndustryPeer ReviewedPostprint (author's final draft

Feasibility of hydraulic separation in a novel anaerobic-anoxic upflow reactor for biological nutrient removal

ABSTRACT : This contribution deals with a novel anaerobic-anoxic reactor for biological nutrient removal (BNR) from wastewater, termed AnoxAn. In the AnoxAn reactor, the anaerobic and anoxic zones for phosphate removal and denitrification are integrated in a single continuous upflow sludge blanket reactor, aiming at high compactness and efficiency. Its application is envisaged in those cases where retrofitting of existing wastewater treatment plants for BNR, or the construction of new ones, is limited by the available surface area. The environmental conditions are vertically divided up inside the reactor with the anaerobic zone at the bottom and the anoxic zone above. The capability of the AnoxAn configuration to establish two hydraulically separated zones inside the single reactor was assessed by means of hydraulic characterization experiments and model simulations. Residence time distribution (RTD) experiments in clean water were performed in a bench-scale (48.4 L) AnoxAn prototype. The required hydraulic separation between the anaerobic and anoxic zones, as well as adequate mixing in the individual zones, was obtained through selected mixing devices. The observed behaviour was described by a hydraulic model consisting of continuous stirred tank reactors and plug-flow reactors. The impact of the denitrification process in the anoxic zone on the hydraulic separation was subsequently evaluated through model simulations. The desired hydraulic behaviour proved feasible, involving little mixing between the anaerobic and anoxic zones (mixing flowrate 40.2% of influent flowrate) and negligible nitrate concentration in the anaerobic zone (less than 0.1 mgN L-1) when denitrification was considered

Sanitation, human rights, and disaster management

Purpose The purpose of this paper is to link debates around the international law on human rights and disaster management with the evolving debate around the human right to sanitation, in order to explore the extent to which states are obliged to account for sanitation in their disaster management efforts. Design/methodology/approach The paper is based on analysis of existing laws and policy relating to human rights, sanitation and disaster management. It further draws upon relevant academic literature. Findings The paper concludes that, while limitations exist, states have legal obligations to provide sanitation to persons affected by a disaster. It is further argued that a human rights-based approach to sanitation, if respected, can assist in strengthening disaster management efforts, while focusing on the persons who need it the most. Research limitations/implications The analysis in this paper focuses on the obligations of states for people on their territory. Due to space limitations, it does not examine the complex issues relating to enforcement mechanisms available to disaster victims. Originality/value This is the first scholarly work directly linking the debates around international human rights law and disaster management, with human rights obligations in relation to sanitation. The clarification of obligation in relation to sanitation can assist in advocacy and planning, as well as in ensuring accountability and responsibility for human rights breaches in the disaster context

Seasonal variation in the nutrient profile of Arthrospira fusiformis biomass harvested from an Ethiopian soda lake, Lake Chitu

The extent of seasonal variation in the nutrient profile of Arthrospira biomass harvested from Lake Chitu was investigated to evaluate the variability of the quality of the product over a period of a year. Protein content varied from 47.9 to 55.7% for wet season biomass samples and from 39.2 to 40.8% for dry season samples. Dry season samples were characterized by relatively higher carbohydrate values (38.0–41.3%). Higher proportion of amino acids and unsaturated fatty acids were recorded for biomass harvested in wet season. Similarly, higher contents of phytonutrients (pigments) were recorded for wet season biomass samples: chlorophyll a (8.2–10.3 mg g−1), phycobiliproteins (104.1–120.7 mg g−1), total carotenoids (3.17–4.31 mg g−1), and β-carotene (1.24–1.61 mg g−1). The contents of Na and K were higher for a dry season biomass whereas other major (Ca, P, Mg) and trace (Mn, Fe, Cu, Zn, Se) minerals were found relatively in higher quantities in a wet season biomass. The nutritional composition of Arthrospira from Lake Chitu was found to be relatively comparable to that found in commercial Arthrospira products in the market. The significance of the findings is discussed in relation to potential sustainable production of Arthrospira biomass from this lake