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Currently, the ecosystem is being damaged in many rivers and subsequently the fish species living there are also facing decline or even extinction. This situation urges to model the habitat and to design suitable restoration strategies in order to increase the capabilities of ecological modeling. In this paper, we proposed a numerical model to assess the ecosystem habitat situation and investigated the impacts of two ecological restorations strategies for the target fish species. The model includes a hydrodynamic model, a habitat model and habitat restoration schemes. The hydrodynamic model simulated the flow properties while sediments in the riverbed were also surveyed. Based on these parameters and fish preference curves, the habitat suitability indices were calculated. In order to analyze the river habitat quality, the weighted usable areas and overall suitability index were also calculated and the effects of the restoration strategies on selected fish species (Freshwater Reeves shad - Tenualosa reevesii) in the Chin-sha River were evaluated. The two ecological restoration strategies: addition of side-channel (scheme I) and river bank reconstruction (scheme II) enhanced the Freshwater Reeves shad habitat suitability level, with the high suitability index proportion increasing from 19.5% to 33.1% for scheme I and to 36.1% for scheme II. Based on the modelling results, we concluded that our numerical model could potentially provide suitable scenarios for successful fish habitat restoration.

In the present work, the degradation of phenol from aqueous solutions was investigated using periodate/zero valent iron nanoparticle (nZVI) in the presence of ultrasound at a batch reactor. The Experimental tests were carried out using pre-designated amounts of nZVI, periodate, and pH ranging from 1-7 mM, 0.5-5 mM, 3-11 respectively. During the all experimental tests the ultrasonic reactor was operated at a fix frequency (40 kHz), temperature (33±1) and power (350 W). The results of nZVI/periodate/ultrasound system on degradation of phenol showed that the removal efficiency was frankly affected by the amount of produced free radicals to initiate the oxidative decomposition of phenol. As, with enhancing the nZVI loading to 3 mM and periodate concentration to 3 mM, the removal efficiency of phenol was increased. Besides, the acidic pH (pH=3) was found to be more effective than neutral and alkaline pH in degradation of phenol.

This study presents the evaluation of a strong base (Purolite A200) and weak base (Purolite PFA847) polymeric anion exchange resins for nitrite removal. The different parameters on the removal of NO2– were investigated in batch sorption mode. Common isotherm models; Langmuir and Freundlich, were used in order to present a description of the equilibrium data. Experimental results showed that the equilibrium data tend to follow Freundlich isotherm model for weak base resin and Langmuir model for strong base resin. The sorption of NO2– on anion exchange resins was found to follow the pseudo-second order kinetic model. The values of thermodynamic parameters proved that ion exchange reaction of NO2– onto such resins are endothermic (ΔH > 0).

Uncontrolled landfill leachate generation portends danger to the environment and aquatic ecosystem, especially without prior treatment before discharge. The application of Al-based coagulants, such as polyaluminum chloride (PACl), has the potential of introducing Al residuals into water bodies. Therefore, an alternative natural coagulant was recommended to reduce the usage of Al-based coagulants. In this study, a coagulation–flocculation process using the combination of PACl as coagulant and Tamarindus indica seed (TiS) as coagulant aid was used in treating the landfill leachate from the Alor Pongsu Landfill Site in Malaysia. Some of the optimum operational conditions determined were the pH and dosage of the coagulant aid, and their effect was considered on parameters, such as suspended solids (SS), color, and COD, using standard jar test procedures. The combination of TiS flocculant reduced the dosage of PACl coagulant from 5,000 mg/L to 2,750 mg/L with removal efficiencies of 99.3%, 97.3%, and 67.4% for SS, color, and COD, respectively.