Pilot studies on high recovery BWRO-EDR for near zero liquid discharge approach

A hybrid process combining reverse osmosis and electrodialysis has been shown to be effective in recovering 97-98% of brackish water as product water with chloride levels of 200 mg/L or less. Potential for scaling on the brine side of the electrodialysis unit was prevented by acidification, operating the electrodialysis in a reversal mode (EDR), and a side loop crystallizer which prevented buildup of scaling components. Settlers, inline microfiltration, and side-loop ultrafiltration kept suspended solids from returning to the EDR unit. This process was demonstrated in a series of more than eighty batch experiments of 1.5 to 1.8 m³ of RO concentrate of raw brackish groundwater from the Negev Highland, Israel. Each batch could be processed within a single day. The feed-water was concentrated from 0.3% to over 10% TDS super-concentrate while producing the water that could be recycled to the RO permeate. This super-concentrate from the EDR unit was further concentrated in a wind powered WAIV unit that brought final brine TDS to > 30%, and showed promise as a method to recover mineral byproducts such as magnesium salt. Initial economic estimates show that this hybrid process is competitive with conventional RO and other enhanced recovery processes for inland desalination requiring use of evaporation ponds.     

The effect of surface treatments on the adhesion of electrochemically deposited hydroxyapatite coating to titanium and on its interaction with cells and bacteria

The effect of different mechanical and chemical pre-treatments on the adhesion strength of hydroxyapatite (HAp) coating on a commercially pure titanium (CP-Ti) substrate was studied by means of a standard tensile test followed by microscopic and chemical analysis to determine the locus of fracture. In addition, the effects of either these pre-treatments or post-treatment by low-energy electron irradiation, which allowed tuning the wettability of the surface, on both osteoblast progenitor attachment and S. aureus bacteria attachment were investigated. A dedicated program was developed for unambiguous identification and count of stained cells. A single-phase HAp coating was formed by electrodeposition. A series of surface pre-treatments consisted of grinding down to P1000, etching in HNO₃/HF solution, grit blast, soaking in NaOH and subsequent heat treatment provided the highest adhesion strength to the HAp coating. Osteoblast progenitors derived from rats may be attached preferentially to a hydrophilic surface (post-treatment to θ = 30°), while the bacteria seemed to be less attached to hydrophobic surfaces (post-treatment to θ = 105°). However, the results were not statistically different. The bacteria seemed to be less attached to the smoother, uncoated surfaces.     

Hydrodynamics and heat transfer in curvilinear channels of rectangular cross section

Experimental results of a study of hydraulic resistance and heat transfer in helical channels of rectangular cross section for laminar and turbulent flows in the isothermal and nonisothermal regimes are given.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 6, pp. 994–1000, June, 1978.     

Electron-induced surface modification of hydroxyapatite-coated implant

Here, the authors report on surface free energy modulation of a hydroxyapatite-coated titanium femoral implant that is performed by a newly-developed method using a low-energy electron irradiation. They observe pronounced increase of hydrophobicity of irradiated samples that occurs in several stages and is characterized by various mechanisms. Bacterial adhesion on electron modified hydroxyapatite samples is studied, by considering different approaches. The authors show that bacterial adherence is selective and depends on the surface free energy components, which were determined from detailed surface free energy analysis. The selective bacterial adhesion, together with the ability to define the surface energy properties, suggests that this newly-developed method opens an avenue for protection of implants from bacterial infections.