BACKGROUND

The wastewater treatment process plays an essential role in our society, as a significant amount of sewage must be cleaned (or treated) before being released back into the environment. There are currently around 15,000 wastewater treatment facilities in the United States of America, many of which utilize the activated sludge process, wherein aerobic micro-organisms are used to digest influent organic matter and remove nutrients. In this process, micro-organisms and other insoluble materials clump together by a process known as flocculation, and the effluent streams include a liquid that is relatively free of suspended solids and organic matter, as well as a sludge resulting from the flocculation and growth of micro-organisms that must be removed and disposed of.

The organisms that digest organic matter do so largely utilizing a process known as aerobic digestion. To accomplish this, an adequate supply of oxygen is needed to feed cellular respiration and treat the wastewater in an effective and timely matter. Due to a high biochemical oxygen demand in the influent organic matter, additional oxygen must be added during the treatment process to ensure the carbonaceous biological matter can be properly digested. This process is known as aeration and represents the overwhelming majority of energy usage in a treatment plant. To accomplish this, a myriad of techniques can be employed, the most popular of which are bubble diffusers and surface aerators.

Bubble diffusers require a fan or compressor to force air down into the bottom of deep tanks, where it is pushed through a fine mesh ensuring a small bubble size, and hence, more surface area per unit volume flow to facilitate oxygen diffusion across the air/water interface. This technique is perhaps the most efficient currently in the industry. Surface aerators are also quite popular and usually involve a cone with helical vanes which rotate in the wastewater, drawing the liquid from the bottom of tanks, splashing it into the air, and agitating the surface. This increases the contact area with air but in an opposite way compared to bubble diffusers, i.e., water is flung into the air instead of air bubbled into the water.

Both of the aforementioned techniques are fundamentally inefficient. For example, while the purpose of bubble diffusers is to introduce oxygen bubbles into the liquid, air must be compressed beyond the static pressure of the bottom of the tank. Additional compression is required to force the air through a fine mesh at its intended flow rate. It is estimated that over 80% of the energy used to compress air is converted into heat. Although this value could be somewhat less for wastewater treatment blowers due to the lower pressure requirements, it is nonetheless not ideal.

Surface aerators, while less complicated and generally cheaper in cost, are even less efficient at delivering oxygen to the micro-organisms in the wastewater. This is not surprising, since much of the oxygen transfer is enhanced through projecting water into the air. This kinetic energy is wasted once the water re-enters the tank.

Thus, a need exists for a device for delivering oxygen to a wastewater stream at a higher efficiency and at lower a lower cost than existing technologies.

SUMMARY

Various implementations include an aeration device. The aeration device includes a venturi tube and an outlet tube. The venturi tube has an outlet port and an air intake port. The outlet tube has a first end coupled to the outlet port of the venturi tube, a second end opposite and spaced apart from the first end, and an intermediate portion disposed between the first and second ends of the outlet tube. The intermediate portion is helically shaped and extends around a helical axis of the intermediate portion. The intermediate portion extends at least one rotation about the helical axis.

In some implementations, the helical axis is disposed at an angle to a gravitational axis. The angle is greater than 0 degrees and less than 180 degrees. In some implementations, the angle is 90 degrees.

In some implementations, the at least one rotation comprises no angled bends in the outlet tube. In some implementations, the at least one rotation comprises three or more angled turns.

In some implementations, the at least one rotation comprises two rotations. In some implementations, the at least one rotation comprises three rotations. In some implementations, the at least one rotation comprises four or more rotations.

In some implementations, the aeration device further includes a pump for pumping a liquid through the venturi tube and the outlet tube. In some implementations, the pump causes the liquid to flow through the outlet tube at 50 gallons per minute or more.

Various other implementations include an aeration system. The aeration system includes two or more venturi tubes and two or more outlet tubes. Each of the two or more venturi tubes has an outlet port and an air intake port. Each of the two or more outlet tubes has a first end coupled to the outlet port of one of the venturi tubes, a second end opposite and spaced apart from the first end, and an intermediate portion disposed between the first and second ends of the outlet tube. The intermediate portion is helically shaped and extends around a helical axis of the intermediate portion. The intermediate portion extends at least one rotation about the helical axis.

In some implementations, each of the second ends of the two or more outlet tubes are coupled together such that the second ends of the two or more outlet tubes are in fluid communication with each other.

In some implementations, the helical axis is disposed at an angle to a gravitational axis. The angle is greater than 0 degrees and less than 180 degrees. In some implementations, the angle is 90 degrees.

In some implementations, the at least one rotation comprises no angled bends in the outlet tube. In some implementations, the at least one rotation comprises three or more angled turns.

In some implementations, the at least one rotation comprises two rotations. In some implementations, the at least one rotation comprises three rotations.

In some implementations, the system further includes a pump for pumping a liquid through the two or more venturi tubes and the two or more outlet tubes. In some implementations, the pump causes the liquid to flow through the two or more outlet tubes at a total of 50 gallons per minute or more.

