Treatment of sewage and industrial wastewater effluents by the cyanobacteria Nostoc muscorum and Anabaena subcylinderica

The potential of two cyanobacteria, Nostoc muscorum and Anabaena subcylindrica to treat sewage and industrial wastewater effluents was investigated. Two different sites were selected for this study which are located at the drains of sewage plant, a salt and soda production company at Kafr El-Zayat city. All samples were taken from the sewage and/or industrial effluents before treatment. Treatment of the sewage and industrial wastewater effluents by using cyanobacteria (N. muscorum, A. subcylindrica and mixed culture of both) revealed that the pH value of the biologically treated wastewater increased, the electrical conductivity was recovered in a range between (4.7–23.9%) and the total dissolved solids were reduced by (4.4–23.3%). The reduction of turbidity level was in a range between (40–96.4%). The removal efficiency of organic matter (COD, PV) was in a range between (20–57.1%) and (25.7–66.7%), respectively. Phosphorus reduction, nitrate treatment and ammonia elimination efficiencies by cyanobacterial system were (20.8–95%), (19.6–80%) and (20.9–96%), respectively. With respect to the treatment efficiency of wastewater by using single or mixed cultures of cyanobacteria, it was observed that the single cultures in most cases was better than the mixed cultures and this may be due to the competition between mixed cultures for nutrients. However, it could be concluded from the presented data that the treatment of wastewater by cyanobacteria is a fruitful method to produce an effluent of high quality to be used for irrigation.     

Green and Ampt infiltration model extended beyond rain duration

A simple method requiring only hand calculations is presented in this study that enables the use of the Green and Ampt infiltration model beyond the rain duration. The method takes into account that the runoff and infiltration processes continue for some period of time after the rain stops. Both the ground surface and subsurface characteristics are considered. A conjunctive overland flow‐infiltration mathematical model is employed for this purpose. A kinematic‐wave approach is used to model the overland flow, and the Green and Ampt equations are employed to calculate the infiltration rates. The governing equations are expressed and solved in terms of dimensionless parameters to enable the generalization of the results based on the principle of hydrologic similarity. A four‐point finite difference scheme is used to solve the governing equations. The results are presented in chart form. An example application of the proposed method is included.     

Hydrologic design aid for urban grass filter strips

A set of generalised charts are presented in this article as a design aid for hydrologic sizing of grass filter strips. The charts express the volume of runoff and the peak flow rate from a grass strip and the residence time in terms of the size and surface and subsurface characteristics of the grass strip as well as the size and surface characteristics of the area draining to the filter strip. These charts are developed by using a mathematical model based on a kinematic‐wave formulation of overland flow and Green‐and‐Ampt formulation for infiltration. The results are obtained in terms of dimensionless parameters and generalised through the principle of hydrologic similarity. An example is included to demonstrate the use of the charts in a practical design problem.     

Recycling of used engine oil by different solvent

The refining of lubricating oils from waste lubricating oil was examined utilizing a novel blend of solvent extraction and activated alumina adsorbent. The activity of these solvent extraction blends {toluene, butanol and methanol (A)}, {toluene, butanol and ethanol (B)} and {toluene, butanol and isopropanol (C)} was evaluated experimentally, oil to solvent proportions from 1:1 to 1:3 were analyzed for mixture blend (C). The results confirm solvent mixture (A) gave good efficiency with the highest percent sludge removal. The maximum percent of sludge removal improves with the increase of solvent to oil ratios. The physical properties of the recycle oil were measured. The results show the change in the properties of recycling oil and have good efficiency.     

Biogas production from municipal sewage sludge (MSS)

Biogas is produced by anaerobic (oxygen free) digestion of organic materials such as sewage sludge, animal waste, and municipal solid wastes (MSW). As sustainable clean energy carrier biogas is an important source of energy in heat and electricity generation, it is one of the most promising renewable energy sources in the world. Biogas is produced from the anaerobic digestion (AD) of organic matter, such as manure, MSW, sewage sludge, biodegradable wastes, and agricultural slurry, under anaerobic conditions with the help of microorganism. Biogas is composed of methane (55–75%), carbon dioxide (25–45%), nitrogen (0–5%), hydrogen (0–1%), hydrogen sulfide (0–1%), and oxygen (0–2%). The sewage sludge contains mainly proteins, sugars, detergents, phenols, and lipids. Sewage sludge also includes toxic and hazardous organic and inorganic pollutants sources. The digestion of municipal sewage sludge (MSS) occurs in three basic steps: acidogen, methanogens, and methanogens. During a 30-day digestion period, 80–85% of the biogas is produced in the first 15–18 days. Higher yields were observed within the temperature range of 30–60°C and pH range of 5.5–8.5. The MSS contains low nitrogen and has carbon-to-nitrogen (C/N) ratios of around 40–70. The optimal C/N ratio for the AD should be between 25 and 35. C/N ratio of sludge in small-scale sewage plants is often low, so nitrogen can be added in an inorganic form (ammonia or in organic form) such as livestock manure, urea, or food wastes. Potential production capacity of a biogas plant with a digestion chamber size of 500 m³ was estimated as 20–36 × 10³ Nm³ biogas production per year.     

Application of differential transform method to unsteady free convective heat transfer of a couple stress fluid over a stretching sheet

In the present article, the transient rheological boundary layer flow over a stretching sheet with heat transfer is investigated, a topic of relevance to non‐Newtonian thermal materials processing. Stokes couple stress model is deployed to simulate non‐Newtonian characteristics. Similarity transformations are utilized to convert the governing partial differential equations into nonlinear ordinary differential equations with appropriate wall and free stream boundary conditions. The nondimensional boundary value problem emerging is shown to be controlled by a number of key thermophysical and rheological parameters, namely the rheological couple stress parameter (), unsteadiness parameter (), Prandtl number (Pr), buoyancy parameter . The semi‐analytical differential transform method (DTM) is used to solve the reduced nonlinear coupled ordinary differential boundary value problem. A numerical solution is also obtained via the MATLAB built‐in solver “bvp4c” to validate the results. Further validation with published results from the literature is included. Fluid velocity is enhanced with increasing couple stress parameter, whereas it is decreased with unsteadiness parameter. Temperature is elevated with couple stress parameter, whereas it is initially reduced with unsteadiness parameter. The flow is accelerated with increasing positive buoyancy parameter (for heating of the fluid), whereas it is decelerated with increasing negative buoyancy parameter (cooling of the fluid). Temperature and thermal boundary layer thickness are boosted with increasing positive values of buoyancy parameter. Increasing Prandtl number decelerates the flow, reduces temperatures, increases momentum boundary layer thickness, and decreases thermal boundary layer thickness. Excellent accuracy is achieved with the DTM approach.     

Review of the phase change material (PCM) usage for solar domestic water heating systems (SDWHS)

The shortage in energy resources combined with the climb in greenhouse emissions is the main incentive beyond the deployment of solar energy resource in various applications. One of the most successful applications is the utilization of solar energy in the domestic water heating systems (DWHS) because 70% of the consumed energy in the residential segment is utilized for space heating and appliances in cold climates 1 . However, the full deployment of solar energy in domestic water heating is only possible when an energy storage system with acceptable price is available. Recently a new tendency for deploying phase change materials (PCMs) as an energy storage system is introduced in several solar DWHS. These systems are known as integrated PCM in solar DWHS and offer several advantages including high storage capacity, low storage volume, and isothermal operation during the charging and discharging phases. The present study reviews various techniques utilized for integrating the PCM in solar water heating systems and the utilized methods for enhancing the heat transfer characteristics of the PCM through the usage of extended surfaces and high conductive additives. Copyright © 2017 John Wiley & Sons, Ltd.     

Biodiversity and technological properties of yeasts from Turkish sourdough

Food Science and Biotechnology - In this study, yeasts were isolated and characterized from twelve traditional sourdough samples which belongs to Black Sea and Aegean regions of Turkey. Twenty six...     

Formal probabilistic analysis of a surgical robot control algorithm with different virtual fixtures

Surgical robots are increasingly being used in operation theaters involving normal or laparoscopic surgeries. The working of these surgical robots is highly dependent on their control algorithms, which require very rigorous analysis to ensure their correct functionality due to the safety-critical nature of surgeries. Traditionally, safety of control algorithms is ensured by simulations, but they provide incomplete and approximate analysis results due to their inherent sampling-based nature. We propose to use probabilistic model checking, which is a formal verification method, for quantitative analysis, to verify the control algorithms of surgical robots in this paper. As an illustrative example, the paper provides a formal analysis of a virtual fixture control algorithm, implemented in a neuro-surgical robot, using the PRISM model checker. In particular, we provide a formal discrete-time Markov chain-based model of the given control algorithm and its environment. This formal model is then analyzed for multiple virtual fixtures, like cubic, hexagonal and irregular shapes. This verification allowed us to discover new insights about the considered algorithm that allow us to design safer control algorithms.