Research Journal of Chemistry and Environment

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Vol. 14(4) December 2010

Inorganics Accumulation in Low-Sludge Wastewater Treatment Technique: Case Study of SBR with Sonication

Zhang Panyue and Zhang Guangming

Large amount of excess sludge imposes great environmental pollution and high handling cost and hence, excess sludge reduction techniques are of great importance. However, inorganics might accumulate in the activated sludge when less excess sludge was discharged. This paper analyzed in detail the accumulation of inorganics in a subsequent batch reactor (SBR) with ‘sonication–cryptic growth’ method to reduce excess sludge. Results showed that for the treatment of normal urban sewage, ‘sonication–cryptic growth’ effectively reduced the excess sludge by around 50%, inorganics accumulation in sludge was insignificant, sludge bioactivity was stable but the effluent turbidity slightly increased. On the other hand, for the treatment of artificial wastewater with 500 mg/L inorganics addition, the inorganics accumulated significantly in the activated sludge and counted for 72% of sludge dry weight after 20 d. Correspondingly, the sludge bioactivity reduced by 55.6%. As a result, the effluent turbidity reached 42 NTU and the COD removal efficiency dropped from 88% to 67%. Interestingly, sonication could improve the sludge bioactivity, reduce the inorganics accumulation and enhance the effluent quality while reducing the amount of excess sludge by around 20%. Therefore, we judged that ‘sonication–cryptic growth’ method did not cause the accumulation of inorganics in sludge and might even improve the sludge activity when high turbidity wastewater was treated.

Kinetics of Photocatalytic Degradation of Methylene Blue in a TiO2 Slurry Reactor

Ovhal Sheetal D. and Thakur Pragati

Textile industry effluents contain large number of dyes. Dyes are found to be toxic and considered to be resistant to biodegradation. Methylene blue (MB) is a representative of a class of dyestuffs resistant to biodegradation. In this work a detailed and systematic investigation of heterogeneous photocatalytic degradation of MB in aqueous TiO2 suspension is presented using 8W low-pressure mercury vapor lamp with a focus to study the effect of various experimental parameters such as initial concentration of MB, concentration of TiO2 as well as addition of electron scavenger H2O2 to obtain complete degradation and decolorization of MB. Degradation was found to increase in the order UV+TiO2+H2O2 > UV+TiO2 > UV+H2O2 > UV. The photodegradation of MB was monitored spectropho¬tometrically by estimating molar concentration changes of MB according to the Beer-Lambert’s law. The rate constants for this heterogeneous photocatalysis were evaluated as a function of concentration of MB, H2O2 and TiO2. A pseudo-first order kinetic has been used to describe the results.

Mathematical modeling of urban air quality: an urban transportation modeling case study in Petaling Jaya, Malaysia

Mahmud A.R., Pradhan Biswajeet, Hadipour M.and Hamsa A. Kadar

This paper provides the findings on a project undertaken to develop a geo-spatial mathematical model relating land-use, road type and air quality. The model shows how spatial elements and issues were quantified to accurately represent the usual and unusual urban environment in the development of residential land-use. The mathematical relationship was based on the optimum distance between residential area and urban transportation network. The spatial data (urban land-use and urban network development) were generated using satellite images, aerial photos and land use maps. Geospatial analyses were performed to find the effect and impact of urban air quality with respect to urban transportation networks. The output of the study would assist the task to reduce negative transport environmental impacts particularly in the field of air pollution. It would also be useful in identifying the potential residential area with respect to urban transportation network towards achieving sustainable development.

Preparation and Characterization of 1:1 adducts of Nickel(II) and Copper(II) p-Methoxydithiobenzoates with Alkylpyridines

Gupta Rashi and Sachar Renu

A series of 1:1 addition complexes of p-methoxydithiobenzoates of nickel(II) and copper(II) with alkylpyridines such as 2, 4-, 2,5-, 2,6- and 3,5- dimethylpyridines and 2,4,6-trimethylpyridine have been prepared and characterized by analytical, molar conductance, spectral and magnetic susceptibility data.

Synthesis, Characterization and Viscosity Studies of Acrylate based Homo and Co-polymers

Ghosh Pranab*, Das Moumita and Das Tapan

Homopolymer of isodecyl acrylate and dodecyl acrylate and their copolymer using different compositions of styrene were synthesised and characterised. Viscosity measurements of synthesised polymers in the toluene solution at 313K were performed. Six different equations viz. Huggins, Kraemer, Martin and Schulz-Blaschke (graphic extrapolation method) and Solomon-Ciuta, Deb-Chatterjee and Schulz-Blaschke (by a single point determination method) were used to calculate intrinsic viscosity, viscometric constants values of the polymer solutions. Molecular weights of the synthesized polymers were determined by Mark Houwink – Sukurda equation. The values of intrinsic viscosity and viscosity average molecular weight, obtained by the two methods (single point determination and graphical extrapolation) were compared in order to verify the validity of the single point determination for the polymers.

Determination and analysis of trace elements and heavy metals in different parts of Mussaenda hainanensis Merr.

Huang Wei-Fei, Qiao Wen-Tao and Yuan Ke

The aim of this research is to analyze trace elements and heavy metals of different parts of Mussaenda hainanensis Merr. The microwave digestion technique was adopted for dissolving the stem, leaf and flower of Mussaenda hainanensis Merr. and to determine content of thirteen trace elements and heavy metals such as Zn, Fe, Cu, Mn, K, Ca, Mg, Ni, Cd, Pb, Cr, Co, Al, Se and As by Atomic Absorption Spectrophotometer method. The relative standard deviation of the method is between 1.28% and 3.06% and the recovery rate by standard addition is between 96.2%and 103.7%. The experimental results showed that the content of K, Mg, Ca, Fe and Mn which is beneficial to the human body, is high in the stem, leaf and flower of Mussaenda hainanensis Merr. The content of the heavy metal Cr, Cd, Pb and As which is harmful to the human body, is lower in the stem, leaf and flower of Mussaenda hainanensis Merr. than the limited quantity as per standards of Chinese Pharmacopoeia, but the content of trace element Cu is high.

Anaerobic Oxidation of Ferrous Iron by Microbial Mixture and its potential to remove Mercury and Nitrate from the Groundwater

Wu Guangyang, Zhang Daoyong and Pan Xiangliang

Groundwater contaminated by nitrate and heavy metals was an important and cosmopolitan environment problem especially in the rural area. However, there are no efficient techniques to remove nitrate and heavy metals simultaneously at present. In this study a mixture of microorganisms was enriched from the sediments of anaerobic aquifer. Experiments demonstrated that the mixture has the ability to reduce nitrate to nitrite and gaseous end product N2 using Fe (II) as the electron donor in anaerobic condition. At the same time, the Fe (II) was oxidized to Fe(III) minerals. The microbial mixture and biogenic Fe (III) minerals have the ability to adsorb mercury ions. In this study, soluble mercury was reduced from 20 μg L-1 to 2.11 μg L-1 in 7 days of incubation in the presence of the microbial mixture and biogenic Fe (III) minerals. This suggests that nitrate and soluble mercury were directly or indirectly removed through the anaerobic oxidation of Fe(II) by AFODN.

Low-temperature synthesis of TiO2 photo catalyst in homogeneous hydrolysis system for dye degradation

Li Longfeng, Meng Xiangdong, Zhang Maolin, Li Guiying and An Taicheng

The nano-crystal anatase TiO2 particles were synthesized by a low-temperature crystallization method with homogeneous hydrolysis of titanium tetrabutoxide [Ti(OBu)4] and the hydrolyzing water was provided by the esterification reaction between the acetic acid (HAc) and ethanol (EtOH). In addition, acetic acid was served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titanium dioxide while the ethanol was also used both solvent and reactants for hydrolyzing water. The effects of different ratios of HAc/EtOH (2:1, 1:1, 1:2 and 1:3) and different cryst¬allization temperature (120, 140, 150, 160, 170 and 180oC) were investigated in details respectively. The pre¬pared TiO2 particles were char¬acterized by X-ray powder diffraction (XRD) and Brunauer-Emmett-Teller (BET) specific surface area. The photo catalytic activity of prepared TiO2 was also evaluated by degr¬ad¬ation of methyl orange (MO) in water at room temperature. The experimental results showed that pr¬e¬pared TiO2 at the low temperature crystallization temperature of 150oC exhibited an excellent phot¬o ca¬ta¬lytic activity comparable to the commercial P25 TiO2.

Electrokinetic Removal of Zinc from Ancient Pyrometallurgical Slag

Xu Zhonghui and Li Dongwei

Ancient pyrometallurgical zinc generated large amounts of slag. Natural leaching from ancient pyrometallurgical zinc sites has contaminated the soil close to the deposits. This work shows the laboratory results of electrodialytic removal experiments on ancient pyrometallurgical slag. Two mainly mechanism of electrokinetic removal of heavy metal from ancient pyrometallurgical slag can be concluded: 1.Heavy metal extracted from the pyrometallurgical slag; 2.The migration and enrichment of the metal ions. The generation of metal hydroxide precipitation could be the most serious factor that influenced the removal rate. Also the water content of slag can not be ignored. The final removal rate of zinc was only 15.77%. Some enhanced technology must be adopted to improve the removal rate.

Defluoridation of Water with Modified Montmorillonite KSF as Adsorbent

Shi Rui and Wu Feng

In this work, defluoridation of water by adsorption using thermal modified montmorillonite KSF was investigated. The influence of some parameters on the adsorption of F- was studied and described in details, such as thermal modification temperature, initial pH value and KSF dosage. The KSF treated at 500 oC had a higher efficiency adsorption of F- than the natural KS. In the initial stage of adsorption, the rate was very quick and the adsorption capacities were increased rapidly. Then the adsorption rate reduced gradually. The adsorption equilibrium can be achieved after 3 hour.

Synthesis of a New Humic Acid Model, 2,4,6,6-Tetrachloro-2-methylcyclohex-4-ene-1,3-dione and Investigation of its Reactions with Monochloramine in Ether and in Methanol

Heasley Victor L.,* Mitrovich Kristin M., Sator Lisa C., Fisher Audra M., Kerk Amber R. E. and Shellhamer Dale F.

This study involves an investigation of the synthesis of a new humic acid model, 2,4,6,6-tetrachloro-2-methylcyclohex-4-ene-1,3-dione (3) and its reactions with monochloramine (NH2Cl) and dichloramine (NHCl2) in ether (H2O as a trace component in the ether is the reactant) and methanol (MeOH). Ring-opened products result from the reac¬tion of (3) and NH2Cl in ether. The reaction of (3) with NH2Cl and MeOH surprisingly gives an epoxide, 3,5,5-trichloro-6-methoxy-1-methyl-7-oxabicyclo[4.1. 0¬] hept-3-en-2-one (11) as the major product and several minor ring-opened products. Results of this study are compared to our previous research on 2,2,4,4,6-pentachloro-5-cyclohexene-1,3-one (pentac¬hlororesorcinol, PCR, (2) with the chloramines in ether and MeOH; the differences in the two reactions are considered in detail. Ion-radical mechanisms are pre-sented for the reactions of (3) with NH2Cl in ether and in MeOH. Reaction of (3) with NHCl2 did not occur.

Removal of dissolved organic carbon by multi-walled carbon nanotubes, powdered activated carbon and granular activated carbon

Poostchi Amir Ali, Mehrnia Mohammad Reza and Sarrafzadeh Mohammad Hossein

Adsorption characteristics of three adsor¬be¬nts, namely multi-walled carbon nanotubes (CNTs), powdered activated carbon (PAC) and gra¬nular activated carbon (GAC) are compared in terms of dissolved organic carbon (DOC) removal from synt¬hetic wastewater. The loading of adsorbents is varied in the range 0.25 - 10 g L-1. Three isotherm models of Freundlich, Langmuir and Tempkin are selected to adjust the experimental data. The solid diffusion coefficient and intraparticular diffusion rate constant at various adsorbent loadings are evaluated. The findings demonstrate that all batch adsorption data are well-fitted with three used isotherm models and CNT adsorbent receives the higher adsorptive qua¬ntity than PAC and GAC. It is also found that pseudo second-order kinetic model predicts adsorption data better as compared by pseudo first-order.

Activity of Sulfate Reducing Bacteria in Successive Alkalinity Producing System: Part I- Effect of Temperature

Lee Sang-Hun, Kim Sunjoon, Jeon Byong-Hun, Bhatnagar Amit, Ji Sangwoo, Cheong Youngwook and Lee Giehyeon

Successive alkalinity producing system (SAPS) is one of the most preferred passive treatment system for acid mine drainage. Sulfate reducing bacteria (SRB) in SAPS make anaerobic environment needed to successive alkalinity production of limestone. It was observed that the SRB activity was most apparent at 36 oC and sulfate removal rate of up to 86% was achieved at this temperature when SAPS had 8 cm thickness of mushroom compost layer and hydraulic retention time (HRT) of 8 days. The sulfate removal rate was directly proportional to the temperature and it significantly decreased at 1 oC. The unexpected observation on the increased effluent sulfate concentration at 1 oC was due to the effect of sulfate elution from the mushroom compost. Iron removal rate was governed by both temperature and thickness of the mushroom compost layer. Finally, cultivation experiments revealed that SRB growth was significantly influenced by the temperature. The results of the present study suggest that the temperature directly influences on the SRB growth and subsequently controls the treatment efficiency of SAPS.

Isolation and Chemically Controlled Studies on Pythium Species: The Causative Agents of Root Rots of Cowpea in Kogi State, Nigeria

Suleiman M.N. and Emua S.A.

Laboratory studies were carried out to isolate, identify and chemically control the fungus associated with root rot of cowpea (Vigna unguiculata (L.) Walp. From samples, two methods of fungal isolation (serial dilution from soil sample and direct plating of infected root) were used. Pythium species was isolated and identified. Benlate, Mancozeb and Ridomil, being the fungicides applied, controlled the mycelial growth of the fungus in vitro, but were not very effective in the field. Ridomil inhibited mycelia growth at 50 ppm, Benlate and Mancozeb controlled the mycelial growth at 150 ppm and 200 ppm respectively. Consequently, a very few sporangia were observed only in Mancozeb at 150 ppm throughout the period of incubation. However, there were levels of significance at 0.05 in the fungicides applied when subjected to analysis of variance.

Molecular Iodine as a catalyst

Mishra Nidhi and Sehegal Preeti

Molecular iodine acts as a catalyst in many organic reactions. It provides inexpensive and quick methods of organic synthesis. It offers green methods of synthesis.

Two-Phase Anaerobic Digestion on high concentration organic wastewater treatment

Li Dongwei, Zhang Shaojian and Wang Kehao

The technology of two phase anaerobic digestion (TPAD) is different from the other new anaerobic reactors. It focuses on the changes of technologies, not on the reshape of reactors' structure. The phase-separation is the essential characteristic of this treatment system. Two-phase anaerobic digestion process fixes the acid-producing bacteria and methanogens respectively in two separate reactor in tandem and provide the own best conditions. The two-phase anaerobic digestion has several advantages over conventional one-phase processes, such as selection and enrichment of different bacteria in each phase, increased stability of the process, higher organic loading rates (OLR) and shorter hydraulic retention times (HRT). Furthermore, two-phase anaerobic digestion system has given the best performances concerning methane productivity, so this technology is helpful to alleviate current solution of the energy shortage and explore the new ways for clean energy.

Applications of GIS in Wetland Management: An Overview

Premalatha M., Abbasi Tasneem and Abbasi S. A.*

GIS is becoming an increasingly useful tool in carrying out environmental management. In conjunction with remote sensing, GIS helps in (i) bringing forth the hidden patterns in a dataset (ii) perform queries (iii) store, edit and retrieve data in the form of maps, tables or graphs and (iv) prepare exceedingly ‘expressive’ maps to facilitate survey, spatial modeling, analysis and decision-making. This paper aims to take stock of the GIS capabilities which are particularly relevant to wetland management.