Design characteristics of showering aeration system

The showering aeration system (SAS) was designed and its performance was evaluated by conducting the aeration experiments in a tank of dimension 2 × 4 × 1.5 m. Initially, the aeration experiments were conducted to optimize the radius of curvature of the SAS with different values, such as = 0, 5, 10, 15, and 20 mm, and maintain other geometric parameters, i.e. number of holes in the shower (); height of water fall (H); diameter of the shower hole (d); volume of water under aeration (V) and water flow rate (Q) as constants. The optimum radius of curvature () was found to be 10 mm. The aeration experiments were further conducted with four different non-dimensional geometric parameters such as the number of holes , the ratio of the height of water fall to the length of shower arm the ratio of the diameter of the hole to the length of shower arm and the ratio of the volume of water to the cube of the length of shower arm The Response Surface Methodology and Box–Behnken Design were used to optimize the non-dimensional geometric parameters of the SAS to maximize the Non-Dimensional Standard Aeration Efficiency. The result indicates that the maximum NDSAE of 16.98 × 106 was obtained from the SAS performance at = 80; = 2; = 4 and = 48. HIGHLIGHT The optimized non-dimensional geometric parameters (H/l; d/l; V/l3; n) for the showering aeration system were experimentally validated, and the final NDSAE value was found to be 16.98 × 106 against the predicted NDSAE value of 17.70 × 106.

Modeling and optimizations of mixing and aeration processes in bioreactors with activated sludge

Mixing aimed at homogenization of the volume of bioreactors with the activated sludge is of great importance for the proper course of the wastewater treatment process. It affects both the efficiency of pollutants removal and the properties of the activated sludge related to its sedimentation. The mixing process in bioreactors can be carried out in different ways. In batch bioreactors in the aeration phase or flow bioreactors in aerobic chambers, mixing is carried out through aeration systems. These systems should aerate the activated sludge flocs for efficient biological treating of wastewater, as well as effectively homogenize the volume of the bioreactor. Hence, it is important to choose such a design of the aeration system and its operation settings that provide the amount of air ensuring the exact amount of oxygen for the implementation of technological processes, counteract sedimentation of sludge at the bottom of the reactor, are reliable as well as economical in operation (demand of electric energy). The paper presents the model studies aimed at optimization of the design and settings of aeration and mixing systems used in active sludge bioreactors.

Pilot-scale study of a structured bed reactor for nitrogen and organic matter removal from sanitary sewage: advances and design challenges

Simultaneous nitrification and denitrification (SND) is a process that can remove both nitrogen and organic matter in a single unit. Several bench-scale studies show that the structured bed reactors (STBR) subjected to recirculation and intermittent aeration have achieved a good performance for SND treating different types of wastewater. Thus, this study took a step forward and evaluated the efficiency and stability of treating domestic sewage in a pilot-scale STBR. COD removal efficiencies higher than 87% were achieved in the whole experimental period. The highest Total-N removal efficiency was approximately 74 ± 7% by adopting a hydraulic retention time (HRT) of 47.2 h and intermittent aeration (2 h aerated and 1 h non-aerated). The setup of the aeration system was an important mechanism to ensure the optimal balance between nitrification and denitrification in a pilot-scale system.

Study of forced aeration system for fruit and vegetable waste composting

Composting of fruit and vegetable waste (FVW) was investigated in a forced aeration system to determine the effects of aeration rate (AR) and aeration method (AM) on compost quality. Rice husk was mixed with FVW as bulking agent to compost for seven days and aerated in continuous and intermittent at rates of 0.3, 0.6, and 0.9 L min−1. Intermittent aeration at rate of 0.3 L min−1 was observed to have higher initial temperature increasing rate and peak temperature compared to continuous aeration. Moisture loss at rate of 0.3 L min−1 was found smaller than other two rates regardless of AM. With comparison made for similar AR, intermittent aeration had experienced less moisture loss with an average of 17.15 %. The pH of compost was found to vary in aeration method where higher peak pH was found in intermittent aeration at low rate, corresponding to their temperature profile. Largest carbon-to-nitrogen (C/N) ratio reduction was attained by compost treated in intermittent aeration at rate of 0.3 L min−1. Further optimization was performed at a rate of 0.1 L min−1, 0.2 L min−1, and 0.4 L min−1. The result showed an improvement at rate of 0.2 L min−1 in intermittent aeration.

The nursery of Litopenaeus vannamei at different density using aeration system on pond

The nursery of shrimp is an intermediate effort to connect hatchery and grow-out process, wherein shrimp fry was rear in a controlled process in a certain time before reared on pond. The study was aimed to evaluate the growth and, survival rate of white shrimp (L. vannamei) under different stocking density in nursery phase on pond. The nursery of L. vannamei was carried out at experimental pond installation of Research Institute for Coastal Aquaculture and Fisheries Extension (RICAFE) in Maros-South Sulawesi using a 5.5 x 11 m2 size of ponds, which was equipped with a bottom aeration system. The water depth of pond was 40 cm. Pond preparation was done by pond repairing, maintaining, drying, and eradicating using 20 ppm of saponin, flushing and water filling gradually until maximum of water level. The fry of L. vannamei (PL-10) with an average initial weight of 0.002g, which obtained from hatchery, were stocked. The treatments were stocking density of L. vannamei fry namely 1,653 individuals/m3 or 40,000 individuals/pond (A) and 909 individuals/m3 or 22,000 individuals/pond (B). Commercial powdered feed was given 3 times/day in 50–100% of biomass weight calculation base. The parameters observed were growth rate, survival rate of white shrimp and water quality condition. The results showed water quality variables including temperature, dissolved oxygen, pH, salinity, and alkalinity were in a suitable range for growth and survival of L. vannamei. The survival rate of L. vannamei in 21 days nursery was 86.40-95.61% and the final weight ranging from 0.292 to 0.320g/ind.

Hydraulic Turbine Performance Assessment with Implementation of an Innovative Aeration System

The environmentally friendly concept in terms of water quality represents a condition for developing hydropower plants all around the world. Since 2017, hydropower has represented more than 70% of all renewable energy production and it is essential for the integration of the other renewable sources of energy and for regulation of the grid. To maintain the “green” label concerning the dissolved oxygen level (6 mg DO/L), the energy suppliers should respond to environmental concerns about the operation of hydropower plants. In the context of sustainable development, the ecological degradation of rivers is unacceptable due to the implementation of a hydropower plant on the watercourse. For deep reservoirs or tropical regions, the oxygen level in the water downstream of the hydropower plants may be low and affect the aquatic life for many kilometers downstream. This paper presents a new aeration system for discharged water from hydropower plants that provides water aeration with minimum energy consumption. The influence of the aeration process on the turbine operation and efficiency is analyzed. Experimental measurements are carried out on site on a small Francis turbine. The influence of the aeration process on the turbine mechanical performances (vibration level and relative displacement) and hydraulic performances (turbine efficiency, power output, and pressure fluctuation) is analyzed. The results showed that the impact of the aeration device implementation and operation over the energetic characteristics of the turbine is in the efficiency measurements accuracy range. The aeration through this device did not influence the turbine operation (vibration, level, or pressure fluctuations).

Upgrading of waste stabilization ponds using a low-cost small-scale fine bubble diffused aeration system

Waste Stabilization Ponds (WSPs) are known for the economical treatment of wastewater, especially if low-cost land is available. In this research to overcome some common operational problems such as undesirable color changes in ponds, severe odor problems, and most importantly, deviations from the effluent standards, the performance of a novel installation of a small-scale fine bubble diffused aeration system in the inlet zone of the facultative pond has been investigated. The long-term operational data of the system in two wastewater treatment plants in the east of Iran demonstrated that this system can significantly improve the efficiency of the treatment plant in addition to eliminating the mentioned operational problems. Pre-aeration of the inlet zone of the facultative ponds (Birjand WSPs) by the aeration system consists of 250 fine bubble disk diffusers (12 inches in diameter) and one 22 kW roots blower showed that purple color and odor problem can eliminate after almost two weeks and organic matter removal efficiency increased from 58 ± 15% to about 85 ± 10% based on BOD5. Almost similar results were obtained from the WSPs of Neyshabur. Long-term experimental results showed this system can be used successfully to control the process and upgrade these natural and efficient treatment processes, especially in developing countries.