AN ORTHOGONAL UNIFORM/PARABOLIC SURFACE PRESSURE HALF-SPACE ELEMENT FOR THE ANALYSIS OF NON-HERTZIAN CONTACT
An orthogonal uniform/parabolic surface pressure half-space element is derived for the analysis of non-Hertzian contact. Restriction is made to parabolic variation of the surface gap in the contact in one orthogonal direction. The surface pressure is integrated analytically over the surface element to obtain influence co-efficeints, e.g. for the normal surface displacement. The coefficients are assembled into matrices leading to a linear system of equations. After solving the parabolic pressure variation is transformed to an equivalent semi-elliptic one coinciding with Hertzian line contact. Adjustments are introduced to approximate the finite size of the bodies in contact. The theoretical predictions are compared to experiments involving the non-Hertzian contact between cylinders of finite lengths.
A Numerical Solution for the Contact Problem Involving Bodies With Cylindrical Surface Considering Cylinder Effect
Solution numerique au probleme du contact entre des corps cylindriques en tenant compte de l'effet du aux formes cylindriques
Parboiled rice effluent: A wastewater niche for microalgae and cyanobacteria with growth coupled to comprehensive remediation and phosphorus biofertilization
Abstract The potential of microalgae and cyanobacteria for bioremediation of wastewater by nutrient uptake combined with simultaneous biomass production is a well recognized perception of today's world. The present study illustrates the treatment of a highly polluted wastewater generated during parboiling of paddy in rice mill industries, widely operational in developing countries where rice is the staple food crop, with the help of microalgal and cyanobacterial isolates capable of growing at high rates in parboiled rice mill effluent (RME). This endeavor leads to comprehensive bioremediation of the said effluent and subsequent use of the harvested biomass as slow release phosphorus biofertilizers and the treated effluent for crop irrigation. The RME-acclimatized algal consortium demonstrated highest growth in terms of fresh weight and greatest remediation efficiency at the end of 36 days' treatment of RME, with 93.9% phosphorus and 100% ammonia-nitrogen removal, 98.7%, 91.6% and 93.5% reduction in biological oxygen demand, chemical oxygen demand and total dissolved solid, respectively, and an increment of 186 ± 0.3 mg L − 1 dissolved oxygen, bringing down the pollutants level well below the discharge limits suggested by Central Pollution Control Board, India. Additionally, microalgae in the consortium aggregated in clumps spontaneously in presence of the filaments of Phormidium sp. facilitating easy harvest. The RME-acclimatized algal consortium demonstrated highest accumulation of polyphosphate (poly-P) (0.76 ± 0.01% of dry weight) as well as highest release of phosphorus in non-sterile soil emphasizing the essential role of soil phosphorus solubilizing organisms to leach soluble phosphorus from the insoluble poly-P present in the biomass. The rice seedlings watered with treated RME also showed improved growth effect on shoot height and leaf width. The study results establish the suitability of RME as an excellent growth media for microalgae and cyanobacteria.