Sludge granulation and efficiency of phase separator in UASB reactor treating combined industrial effluent

Sludge granulation and the effect of gas-liquid-solid separator （GLSS） design on the efficiency of upflow anaerobic sludge blanket （UASB） and upflow anaerobic sludge filter （UASF） reactors, operating at HRTs ranging from 3 to 12 h was investigated. VSS/TS ratio gradually increased in both the reactors with increasing sludge age （from 0.5 to more than 0.7 for UASB reactor and 0.012 to 0.043 for UASF reactor）. X-Ray diffraction analysis of the UASF sludge showed the presence of expanding clays revealing its additional absorption capability. Fuoraphyllite and albite precipitation related to excellular polymers of the microbial shell structure, showed the extended growth of microorganisms during sludge granulation. A gradual decrease （82%-69%） in COD removal with decreasing HRT was apparent in UASF reactor. In case of UASB reactor, this decrease was marginal because addition of GLSS device significantly improved （14%-20%） the overall efficiency of the UASB reactor. GLSS enhanced the efficiency of the UASB reactor by increasing the settleability of suspended particles and accelerating the coagulation of colloidal particles due to the velocity gradient.

Decolorization of Blue CL-BR dye by AOPs using bleach wastewater as source of H_2O_2

This research was focused on the investigation of the efficacy of advanced oxidation processes （Fenton, ozonation and UV/H2O2） for decolorization of reactive azo dye （Blue CL-BR） using bleach wastewater as possible source of H2O2. All the experiments were performed on the laboratory scale set-up. The results showed that colour removal efficiencies by UV or bleach （H2O2） alone were not so efficient. Fenton process with bleach wastewater was found to be the most effective at process conditions such as pH of 3 and HEO2/Fe^2＋ ratio of 24：1, resulting in 64% colour removal. Almost complete colour removal, i.e., 99% and 95% were achieved by UV//H2O2 and UV/bleach wastewater in 30 and 60 min, respectively. Ozonation proved an efficient method for decolorization of Blue CL-BR dye at alkaline pH. It was possible to achieve 98% colour removal with 30 min of ozonation at pH 9. The colour removal of dye was found to follow first order kinetics.

Assessment of Metals Concentration and Ecotoxicology of the Sediment Core of Rehri Creek, Karachi Coast, Pakistan

Trace metal concentrations were investigated in a recent sediment core collected from the Rehri Creek area of the Karachi coast, Sindh - Pakistan. The core was sliced horizontally at 2.5-cm intervals to determine grain size, sediment composition, pH, organic matter, and acid-leachable trace metals： cadmium, chromium, copper, lead, and zinc. The trace metals were analyzed by ICP. To separate anthropogenic from geogenic input, several approaches were made, including comparison with sediment quality guidelines--ecotoxicological sense of heavy metal contamination and classification by quantitative indexes. Grain-size analysis and sediment composition of core sample show a sandy nature with neutral pH. Elemental sequence （ES） of the trace metals is in the order of Zn （19.2-109.56 ppm） 〉 Si （66.46-101.71 ppm） 〉 Ba （12.05-26.86 ppm） 〉 As （8.18-17.36 ppm） 〉 Ni （4.2- 14.69 ppm） 〉 Cr （3.02-9.62 ppm） 〉 Pb （2.79-6.83 ppm） 〉 Cu （2.2-5.29 ppm） 〉 Co （0.9-2.05 ppm）. Thus it is likely that the area may face a serious threat of metal pollution with the present deposition rates unless stringent pollution control norms are adopted. The Sediment Geo-accumulation Index shows that there is no Cr, Cu, Ni, Pb, Zn, or Fe pollution; however, the former index and the Pollution Load Index indicate arsenic pollution in the sediments.

Implementation of Variable Tone Variable Bits Gray-Scale Image Stegnography Using Discrete Cosine Transform

Secure exchange of information is the basic need of modern digital world of e-communication which is achieved either by encrypting information or by hiding information in other information called cover media. Concealing information requires a well designed technique of Stegnography. This work presents a technique, variable tone variable bits (VTVB) Stegnography, to hide information in a cover image. The VTVB Stegnography hides variable data in discrete cosine transform (DCT) coefficients of the cover image. VTVB Stegnography provides variable data hiding capacity and variable distortion. Additional large data hiding this technique provide extra security due to the large key size making VTVB Stegnography technique much more immune to steganalysis. The hiding makes the existence of information imperceptible for steganalysis and the key of keeping a secret makes the recovering of information difficult for an intruder. The key size is depending on cover image and numbers of bits of discrete cosine transform (DCT) coefficients used for information embedding. This is a very flexible technique and can be used for low payload applications, e.g. watermarking to high payload applications, e.g. network Stegnography.

On Hiding Secret Information in Medium Frequency DCT Components Using Least Significant Bits Steganography

This work presents a new method of data hiding in digital images,in discrete cosine transform domain.The proposed method uses the least significant bits of the medium frequency components of the cover image for hiding the secret information,while the low and high frequency coefficients are kept unaltered.The unaltered low frequency DCT coefficients preserves the quality of the smooth region of the cover image,while no changes in the high DCT coefficient preserve the quality of the edges.As the medium frequency components have less contribution towards energy and image details,so the modification of these coefficients for data hiding results in high quality stego images.The distortion due to the changes in the medium frequency coefficients is insignificant to be detected by the human visual system.The proposed methods demonstrated a hiding capacity of 43:11%with the stego image quality of a peak signal to the noise ration of 36:3 dB,which is significantly higher than the threshold of 30 dB for a stego image quality.The proposed technique is immune to steganalysis and has proved to be highly secured against both spatial and DCT domain steganalysis techniques.

Increasing Distance Increasing Bits Substitution (IDIBS) Algorithm for Implementation of VTVB Steganography

Cryptography and steganography are two important and related fields of information security.But,steganography is slightly different in the sense that it hides the existence of secret information from unauthorized users.It is one of the most appealing research domains,have applications like copyright protection,data integrity protection and manipulation detection.Several steganography techniques have been proposed in literature.But,in this work a new information hiding algorithm is presented.The proposed technique de-correlates frequency components of cover image using discrete cosine transform and uses the least significant bits of frequency components for hiding secret information.The tech-nique hides variable number of bits of secret message in different frequency components.Therefore,it hides different amount of secret information in different regions of cover im-age and results in enhancement of security.The algorithm has the flexibility to change the hiding capacity and quality of final stego image.It has been observed from experimental results that a hiding a capacity from 3%to 43%can be achieved with significantly good quality of 41 dB to 37 dB in term of peak signal to noise ratio.The successful recovery of the hidden information need the pattern,called stego key,in which is used in hiding process.The algorithm provides twofold security;hiding keeps the existence of hidden information secret and the large key size makes the retrieval of hidden information difficult for intruders.

Role of Canal Lining on Groundwater Fluctuations: A Modeling Simulation Approach for Jaalwala Distributary, Bahawalnagar

Jaalwala Distributary was selected to see the consequences of concrete lining on the underlying saline groundwater table. Its middle and tail portions were concrete lined whereas the head portion was still unlined. Visual MODFLOW 2011.1 was used to simulate the effects of concrete lining on saline groundwater in two-dimensional format. Simulation results showed a gradual rise of electrical conductivity (EC) up to 7000 μS/cm and decline in water table depth to nine feet (2.74 m). It observed negligible inflows from the distributary through its western boundary due to formation of a permanent barrier in the way of seepage of any kind. Results have further predicted that freshwater layer available beneath the Jaalwala Distributary (before its lining) will finish ultimately and the below present saline water also move upward to take this vacated place. Hence it was concluded to line the canals of saline water areas from their sides which will not only protect them from erosion but canal water theft as well.