Parameter optimization of ferro-sonication pre-treatment process for degradation of bisphenol A and biodegradation from wastewater sludge using response surface model

In this study, the application of response surface model in predicting and optimizing the ferro-sonication pre-treatment for degradation of bisphenol A (BPA), an endocrine disrupter compound from wastewater sludge (WWS) was investigated. The ferro-sonication pre-treatment process was carried out according to central composite design (CCD) with four independent variables such as wastewater sludge solids concentration, pH, ultrasonication time and FeSO(4) concentration. The effect of ferro-sonication pre-treatment was assessed in terms of increase in sludge solids (suspended solids (SS) and volatile solids (VS)) and organic matter (chemical oxygen demand (COD) and soluble organic carbon (SOC)) solubilization and simultaneous BPA degradation from WWS. It was observed that among all the variables studied, ultrasonication time had more significantly affected the efficiency of the ferro-sonication pre-treatment process followed by FeSO(4) and solids concentration. Through this optimization process, it was found that maximum BPA degradation of 88% could be obtained with 163 min ultrasonication time, 2.71 mg/L FeSO(4) concentration, pH 2.81 with 22 g/L SS. Further, the effect of ferro-sonication pre-treatment on biodegradation of WWS was also studied. It was observed that ultrasonication time had significant effect and the higher biodegradation (32.48%) was observed at 180 min ultrasonication time.     

An availability model for MIN-based multiprocessors

System decomposition is a novel technique for modeling the dependability of complex systems without constructing a single-level Markov Chain (MC). This is demonstrated in this paper for the availability computation of a class of multiprocessors that uses 4×4 switching elements for the multistage interconnection network (MIN). The availability model is known as task-based availability, where a system is considered operational as long as the task requirements are satisfied. The authors develop two simple MC's for the processors and memories and solve them using a software package, called HARP. The probabilities of i processing elements (PE's) and j memory modules (MM's) working at any time t, denoted as Pi(t) and Pj(t), are obtained from their corresponding MC's. The effect of the MIN is captured in the model by finding the number of switches required for the connection of i PE's and j MM's. A third MC is then developed for the switches to find the probability that the MIN provides the required (i×j) connection. Multiplying this term with Pi(t) and Pj(t), the probability of an (i×j) working group is obtained. The methodology is generalized to model arbitrary as well as larger size systems. Transient and steady state availabilities are computed for a variety of MIN configurations and the results are validated through simulation     

A harmonic elimination and suppression scheme for an open-end winding induction motor drive

In this paper, a harmonic elimination and suppression scheme for a dual-inverter-fed open-end winding induction motor drive is presented. Two isolated dc-link sources with voltage ratio of approximately 1 : 0.366 are required for the present drive. These two isolated do links feeding two inverters to drive the open-end winding induction motor eliminate the triplen harmonic currents from the motor phase. The pulsewidth-modulation scheme proposed enables the cancellation of all the 5th- and 7th-order (6n /spl plusmn/ 1, where n = 1, 3, 5, 7, etc.) harmonic voltages and suppresses the 11th- and 13th-order harmonic voltage amplitudes in the motor phase voltage, in all modulation ranges. The next higher order harmonics present in the motor phase voltages are 23rd, 25th, 35th, 37th etc. (6n /spl plusmn/ 1, n = 4, 6, etc.). By using triangular carrier wave and proper modulating waves for each inverter, the open-end winding induction motor can be operated in the entire modulation range, eliminating all the 6n /spl plusmn/ 1 harmonics (n = 1, 3, 5, 7, etc.) coupled with 11th and 13th harmonic suppression. The proposed scheme also gives a smooth transition to the overmodulation region.     

Tannase production by Bacillus licheniformis KBR6: Optimization of submerged culture conditions by Taguchi DOE methodology

Tannase production by Bacillus licheniformis KBR6 under submerged fermentation was optimized following Taguchi orthogonal array (OA) design of experiment (DOE). An OA layout of L18 (2¹ × 3⁵) was constructed with six most influensive factors on tannase biosynthesis like, carbon source (tannic acid), phosphate source (KH₂PO₄), nitrogen source (NH₄Cl), metal ion (Mg²⁺), incubation temperature and initial medium pH at three levels for the proposed experimental design. Tannase yield obtained from the 18 batches fermentation with the selected levels of each factors were processed with Qualitek-4 software at bigger is better as quality character and obtained a specific combination of factors with a predicted tannase production of 0.362 U/ml. The optimal combinations of factors (tannic acid, 1.0 g%; KH₂PO₄, 0.45 g%; NH₄Cl, 0.35 g%; MgSO₄, 0.05 g%) obtained from the proposed DOE methodology was further validated by fermentation experiment and the obtained result revealed an enhanced tannase yield of 2.18-fold (from 0.163 U/ml to 0.356 U/ml) from its unoptimized condition. Taguchi approach of DOE resulted in evaluating the main and interaction effects of the factors individually and in combination.     

Solid phase extraction of europium and uranium using Tulsion CH-90 resin

A procedure for the pre-concentration and separation of trace amounts of Eu and U by solid phase extraction using Tulsion CH-90 resin (with imino diacetate functional group) has been developed. The determinations of europium and uranium have been carried out by a radiotracer technique using ^152,154Eu and ²³³U radionuclides. The experiments were carried out using both batch and column techniques. Parameters such as equilibration rate, effect of pH, sorption and desorption of metal ions have been studied. The maximum sorption capacities for Eu and U were found to be 0.31 mmolg^–1 at pH 5.3 and 0.96 mmolg^–1 at pH 3.1 respectively.     

Interfacial mechanisms controlling phase formation in sol-gel derived lead zirconate titanate thin films

An RBS study has been carried out to study the relative extent of Pb diffusion in the substrate from PZT films. It is found that extensive diffusion of Pb occurs into the quartz substrate making the film severely deficient in Pb. No such diffusion occurs in the case of PZT films on sapphire and the concentration of Pb is near stoichiometric, except for a small loss due to volatilization. Excessive Pb deficiency, rather than any epitaxial effect, has earlier been proposed by us to be the crucial factor responsible for the existence of the pyrochlore phase in PZT thin films on substrates such as Si, glass, quartz etc. The present results confirm this. The effects of other process variables such as thickness and chemical composition (Zr/Ti ratio) of the film can also be understood in terms of the same phenomenon.     

Advancement in treatment of wastewater: Fate of emerging contaminants

The scarcity of industrial and domestic use water has become an important issue as industrial operations and localized pollution have burgeoned over the last decade. Wastewater (WW) treatment for recycling and reuse is gaining importance as an alternate source of water supply to circumvent water shortages. Wastewater treatment requires thorough planning, design, construction, and management of treatment facilities in order to discharge the treated water to the aquatic environment or for recycling and reuse. One detrimental effect of growing populations and urbanization has been the release of many persistent emerging contaminants (ECs) to the environment, mainly detected in WW. The entry of these ECs to the aquatic environment through wastewater treatment plants (WWTPs) may cause different ecological risks such as reproductive toxicity, endocrine disruption, and microbial resistance. The quantification of ECs (in ng or pg level) in complex matrices, such as WW samples recognized through non‐target screening approaches, has played a key role in the planning and design of water treatment facilities. The purpose of this review is to provide information about advancements in wastewater treatment technologies such as constructed wetland (CW) and advanced oxidation processes (AOPs) and the fate of emerging contaminants during these treatments. Further, this review also reports the ecological effects of these contaminants and their by‐products formed during various advanced WW treatment processes. The review also discusses advancements in different analytical techniques for the analysis of ECs in WW.     

Electrochemical behavior of nanostructured graphene nickel phosphorus composite coating on copper

Journal of Applied Electrochemistry - The present work is focused on the effects of graphene addition on the electrochemical performance of environmentally benign nanostructured...