Water Online

May 2016

Water Innovations gives Water and Wastewater Engineers and end-users a venue to find project solutions and source valuable product information. We aim to educate the engineering and operations community on important issues and trends.

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nitrogen from the filtrate compared to the baseline (90 percent and 99 percent removal of ammonia-nitrogen with anammox and PAD, respectively) and can achieve similar effluent quality. • Energy invested in either sidestream treatment technology results in less energy required for nutrient removal in the aeration basins (by approximately 7 percent). For sidestream treatment with anammox, the energy saved in the aeration basins overcomes the energy required for sidestream treatment. • Considering energy use, chemical use, and biosolids production together, sidestream treatment with PAD demonstrates a net annual energy cost savings of 5.1 percent relative to sidestream treatment with anammox and a net annual energy costs savings of 19.1 percent relative to the baseline. These savings are attributed to significantly lower biosolids hauling and disposal costs due to the volatile solids destruction associated with PAD. The baseline (no sidestream treatment) offers the lowest capital cost because construction of a sidestream treatment facility costs more than the construction of a methanol feed and storage facility. • Sidestream treatment with PAD offers the lowest annual cost primarily due to the significant savings in biosolids hauling and disposal. • The lowest 20-year net present value is equivalent for the baseline (no sidestream treatment), sidestream treatment with PAD, and sidestream treatment with anammox alternatives. Conclusions Both PAD and anammox offer nitrogen removal without the need for supplemental carbon or alkalinity, but PAD should be considered when there is also a desire for additional volatile solids destruction. PAD would be ideal for facilities with high and/or volatile biosolids disposal costs or a long haul distance. Anammox should be considered when the additional desire is energy minimization. Anammox would be ideal for facilities with high energy rates, volatile energy rates, or a desire to achieve net zero energy. This evaluation made reasonable assumptions; however, every site is different, and different assumptions would affect the cost evaluation. For example, the assumption for a greenfield site was made in order to produce an apples-to-apples comparison, but a retrofit installation would significantly affect the cost evaluation. Moreover, if a spare tank is available, blowers, diffusers, and controls could be cost-effectively incorporated to create a PAD facility. n 14 wateronline.com n Water Innovations NUTRIENTREMOVAL Heidi Bauer, PE, joined CH2M in 2008 and has enjoyed working on wastewater modeling, master planning, and design projects for wastewater and biosolids treatment. Prior to joining CH2M, Heidi worked as a contract operator and currently holds Colorado certi- fications for Class A water and wastewater, Class 3 collections and distribution, and Biosolids Land Appliers. About The Authors Bruce Johnson, global technology leader for wastewater simulation, joined CH2M in 1995 and brings more than 26 years of experience operating, troubleshooting, and designing water and wastewater treatment plants and equipment. He is seen as an expert in modeling and designing wastewater treatment facilities and has made a lasting impact on the wastewater profession through the high-end applica- tion of wastewater simulation to advanced waste treatment design. He holds five patents in wastewater technologies and has authored/ co-authored more than 25 technical papers on the subject. He was recently named an IWA Fellow by the International Water Association. Figure 5. Process flow diagram for sidestream treatment with anammox PAD targets digester effluent, while anammox targets the filtrate or centrate produced from dewatering. Tom Johnson joined CH2M as a Senior Technologist in 2005. With more than 17 years of experience working in the water industry, Tom specializes in wastewater process analysis, modeling and design, wastewater collection and conveyance, as well as wastewater treat- ment plant optimization and efficiency.

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