Integration of coagulation and electro-activated HSO5− to treat pulp and paper wastewater

Pulp and paper wastewater (PPW) is classified as complex wastewater that contains high concentrations of recalcitrant pollutants. In this study, the integration of coagulation process and electro-activated peroxymonosulfate (PMS) were tested to treat PPW. FeCl3, aluminum sulfate and poly aluminum chloride were examined for chemical oxygen demand (COD) removal from PPW. Amongst the coagulants, FeCl3 showed higher performance compared to other coagulants in which 55% of COD was removed under the conditions of natural pH of 6.9 and FeCl3 dosage of 100 mg L−1. Coagulation-treated wastewater by FeCl3 was treated by electro-activated PMS. Under the condition of 0.75 mA cm−2 current density, 6.0 mM PMS and 60 min reaction time, 53% of COD was further eliminated. To compare with electro-Fenton, electro-activated PMS provided higher COD removal and specific oxidant efficiency. Integration of coagulation (FeCl3) and electro-activated PMS enhanced the biodegradability of PPW based on biochemical oxygen demand/COD index. The results showed that integrated chemical and electrochemical processes can be used as a pretreatment for biological process

LED visible light assisted photo-oxidation of acetaminophen using one-step synthesis of Cu,Fe@g-C3N4 nanosheet – Activated persulfate system in aqueous solutions

In this work, the synthesis of Iron (Fe) and Copper (Cu) co-doped g-C3N4 was performed using the thermal decomposition of urea while iron nitrate and copper nitrate were used as dopant precursors. The fabricated catalyst (Fe-Cu@g-C3N4) was coupled with visible light and used for acetaminophen (APAP) degradation. The synthesized catalyst was characterized via several techniques including XRD, BET, BJH, SEM, TEM, EDX, EDS Dot mapping, DLS, and UV–Vis deflective reflectance spectroscopy. The performed characterization tests confirmed the successful synthesis of Fe-Cu co-doped g-C3N4 with high purity, nano-sheet structure and high porosity (79.93 m2/g). The complete APAP decomposition efficiency was achieved under optimal experimental conditions including pH of 11, catalyst dosage of 10 mg/L, PS dosage of 1 mM, and APAP concentration of 4 mg/L. The scavenging tests confirmed the major contribution of sulfate radicals and consequently, hydroxyl radicals for APAP removal. In addition, the kinetics of APAP degradation was studied and it revealed the pseudo first–order kinetics with 0.0698 min−1 rate constant. Finally, a plausible and tentative decomposition pathway was proposed for APAP degradation. The results of this study confirmed that the LED/catalyst (Cu, Fe@g-C3N4)/PS process could be an efficient and robust process for antibiotic-containing wastewater including hospital wastewater

Prioritization of watersheds in order to perform administrative measures using fuzzy analytic hierarchy process

Prioritization of watersheds in order to perform administrative measures is necessary and inevitable. Determining areas of top priority for flood control projects is a managerial decision that should be approved by studies of physical, social and economic status of the region of interesrt and by assessing the outcomes of the past operations. Therefore, the aim of this research was to study morphological and physiographic characteristics, and to use geographic information systems (GIS) and multi-criteria decision-making methods (MCDM), to identify the critical sub-basins which have the tendency to be destructed, in Galikesh watershed, Golestan province. This watershed is important, yet critical, in terms of land use change, erosion and flooding in the Golestan Province, Iran. In total, nine morphological parameters were used to prioritize sub-watersheds using fuzzy analytic hierarchy process (FAHP). The morphological parameters were by some means linked to watershed drainage system. Based on FAHP approach, sub-basins, as vulnerable zones, have been evaluated and cetegorized in five priority levels (very low, low, medium, high and very high levels). The results showed that 44.44% and 22.22% of sub-basins were categorized respectively under average, and high to very high levels, suggesting that the conservation and management measures are essential in order to maintain stability in the region. Thus, the FAHP technique is a practical and convenient method to show potential zones in order to implement effective management strategies, especially in areas where data availability is low and soil diversity is high. Finally, it can be said that without having to encounter high costs and a waste of time, sub-basins could be categorized by means of morphometric parameters in order to implement conservational measures to simutaneously conserve soil and the environmen