Issue 2

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.

In the present investigation, an attempt for the reduction of six hazardous air Pollutants (HAPs) from diesel exhaust by different blends of diesel and biodiesel has been made. The synthesis of biodiesel has been done from Jetrofa, Linseed Castor and Karanja oils which are commonly used in the Indian market. Blending of diesel with biodiesel was done in different ratios (20 to 40 %) for the estimation of carcinogenic HAPs from the exhaust of a Honda engine (EBK 2010AC Model). The order of HAPs emission from engine exhaust by using diverse blends were Diesel>Jatropha-diesel>Linseed-diesel>Castor-diesel> Karanja-diesel. The maximum reduction of HAPs was established in the following ratio 40% (Biodiesel):60% (Diesel). B(a)P and Chrysene were the two individual aromatic hydrocarbons (AHCs) found in higher concentration in almost all blending fuels, ranging between 50 ng/µl to 101.1 ng/µl. The emission of almost all AHCs reduces by Blending of Diesel with Biodiesel. This was the first comprehensive information which showed the reduction of carcinogenic pollutants from diesel exhaust.

Mesophilic biomass and thermophilic biomass samples were isolated and used to remove Dorasyn Red dye from aqueous solutions. The biosorption kinetics of dye uptake by four different types of biomass at three temperatures (20, 30, and 40 °C) were investigated using pseudo-first order kinetics, pseudo-second order kinetics, intraparticle diffusion, Elovich, and Bangham models. The pseudo-second-order kinetics model and the first stage of the intraparticle diffusion model were effective in describing the experimental kinetics data. The biosorption results showed that the mesophilic biomass samples could be useful for removing dye under acidic conditions.

The present study investigated the possible effect of contact time, initial nickel concentration, and adsorbent concentration on removing Ni (II) ion, which is toxic to living organisms, from the aqueous media using nano zero valent iron (nZVI) and nano zero valent iron coated powdered activated carbon. A large portion of the nickel removal was achieved in a contact time of five minutes. A removal efficiency of barely 24% was able to be achieved only using activated carbon, while the nickel removal was achieved by approximately 80% using 200 mg/L nZVI. On the other hand, the efficiency was observed to increase up to 99% even with the particle containing the lowest nZVI in the experimental studies using the AC-nZVI nanoparticles containing AC at a rate of 25%, 50% and 75%. Adsorption capacity was increased from 125 mg/g and 820 mg/g for activated carbon and nZVI, respectively to 1190 mg/g for 50% AC-nZVI. Based on our study results, the effect of nZVI is promoted when nZVI is synthesized together with activated carbon. The Freundlich model was also found the best to represent the isotherm modeling made for nZVI.