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The effluent flows from the 91 st Avenue Wastewater Treatment Plant (WWTP) are a coveted and valuable water resource in the Phoenix area. The current effluent flows of 130-150 mgd are nearly fully allocated, providing cooling water to the Arizona Nuclear Power Project (ANPP) and supplying agricultural users in the Buckeye Irrigation District (BID). The Tres Rios flow regulating and overbank wetlands provide a second tier of reuse. Whilst conveying the effluent to downstream customers, the wetlands provide approximately 300 acres of rare and valuable wetland habitat. In addition, the wetlands will remove total residual chlorine naturally, and achieve advanced ammonia and total nitrogen removal. This paper provides a summary of the wetland design and discusses the challenges of operating a large scale constructed wetland. These include optimizing process control and vegetation maintenance to maintain habitat value and meet treatment objectives, balancing water requirements of the wetlands with downstream customers, controlling mosquitoes and other vectors, overcoming regulatory hurdles, and assessing the cost/benefits of the wetlands over mechanical treatment processes.

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We present the design of a cheap and easy to build pulse generator, which is both reliable and robust enough for everyday use within the Microwave laboratory (as a power supply for the continuous-wave GHz 1 oscillator). The design goals for the pulse generator are: voltage amplitude of V 24 max = V , output current of at least mA 100 = I , fundamental frequency of kHz 1 = f, and a 50 % duty cycle. The essence of the generator is its simplicity, where an IC NE555 is used to drive a power transistor output, thus providing high current for a relatively low impedance load. The generator is designed and simulated using Orcad pSpice. Rigorous testing and measurements, performed on a fabricated prototype, show excellent agreements with the design goals and with the computer aided simulated results.

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