Characteristics of Submerged Flow Below Gate With Sill in Non-Prismatic Channels
The characteristics of submerged flow below vertical gate with sill upstream of horizontal diverging channel reach are analyzed based on experimental investigation. The experimental program is conducted in a laboratory flume with 10 cm wide, 31 cm deep and 3.0 m long. A diverging channel reach with fixed length and constant divergence angle is used. Polygonal sills with constant height, constant upstream slope and variable downstream slope are used under the gate. These sills are tested under wide range of similar submerged flow conditions to investigate the effect of sill slope on the flow characteristics. Also, a particular sill is tested under different heights to address the effect of sill height on the flow characteristics. Both the effects of submergence and the under-gate Froude number on the flow below the gate are discussed. Different flow regimes are considered (Supercritical, critical and subcritical flow). It is found that the presence of sill under the gate upstream of diverging channel reach has a remarkable effect on the discharge coefficient of the gate. It is noticed that the submergence ratio and the upstream head ratio are not able to explain the observed variations (or scatter of data) in the discharge coefficients. These variations or scatters are completely explained by the under-gate Froude number and the differential head ratio.
Hydraulic Jump within Gradually Expanding Channel
This expanding channel jump is considered to behave as a section of a circular jump. Equations describing the characteristics of the expanding channel jump are derived. The observations were conducted using six different angles of divergence. The experimental results showed a close agreement with the theoretical solutions. The general equation developed for the jump, with proper evaluation of the side pressure force effect, describes the phenomenon regardless of the angle of divergence. An empirical expression for approximating the location of the jump within the transition was also developed.
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.