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Improved Onsite Wastewater Disinfection and Nutrient Removal for Safe Discharge and Reuse

Liu, Kun
http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588070537771

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Environmental Science.
For onsite wastewater reuse or discharge, fixed media biofilters provide high treatment efficiency with relatively low cost and maintenance. However, these biofilters are not designed to provide disinfection or remove nutrients. Advanced treatment processes are needed to reduce public health and environmental risks before reuse or discharge into surface water. The objectives of this study were to improve onsite wastewater disinfection, to enhance cold weather ammonia removal, and to develop an advanced natural nutrient removal system. The existing disinfection systems used for onsite wastewater treatment are flow-through UV and chlorine systems. They both have disadvantages. Flow-through systems using UV lamps have continuous lamp operation with fluctuating flows. Mineral and humic substances foul the lamps and solids accumulate in the disinfection chambers. Flow-through chlorine tablet systems introduce the disinfectant as it dissolves in the flowing water. Variations in flow rate results in inconsistent tablet dissolution and chlorine dosing. Batch UV and chlorine disinfection proved to overcome the drawbacks of conventional systems. The batch UV system shortened daily operation time by two-thirds and eliminated solids settling. The batch design reduced lamp fouling and maintenance while sustaining high disinfection effectiveness. Batch chlorine system using a slow-release chlorine agent provided precise control of chlorine dose, allowed for longer contact time and reduced dosing frequency. The 9- and 6-months field tests for UV and chlorine batch systems showed their effectiveness and reliability. This study showed that batch UV and chlorine systems are both improved alternative onsite disinfection systems. Cold temperature often reduces ammonia removal efficiency in wastewater treatment systems. Improving ammonia removal by warming biofilters in cold weather has not been tested yet. This study investigated two methods to warm biofilters: covering the biofilter surface with polyethylene films and covering the biofilter with insulation in a greenhouse. The results showed that both treatments significantly increased the biofilter temperature by 4 °C on average. However, ammonia removal was not improved correspondingly. Instead, both warming methods might pose negative impacts on biofilters. Anaerobic conditions were established within the covered filters which resulted in loss of ammonia removal capability. The ammonia removal performance of sand biofilter might be affected by many other factors other than just temperature. Biofilter effluent nitrogen and phosphorus are plant nutrient. An advanced nutrient removal system was developed using a hydroponic floating bed systems with perennial ryegrass. Hydroponic floats and floating beds were designed and tested to solve the issues of consistent seed germination and algae control. The results showed that customized opaque floats and shaded rack with misters offered even grass seeds germination with no surface algae growth. The customized floats that filled the hydroponic beds also insured algae control in the treated effluent. This simple system allowed the plants to grow optimally and develop a healthy root mat under the hydroponic floats, which significantly enhanced the nutrient removal efficiency. Such floating bed systems could alleviate the environmental risk of onsite wastewater discharge and produce an easily harvested, usable crop while reducing the nutrient load into surface water.
Karen Mancl (Advisor)
Jiyoung Lee (Committee Member)
Olli Tuovinen (Committee Member)
Peter Ling (Committee Member)
176 p.
Environmental Science

Recommended Citations

Citations

  • Liu, K. (2017). Improved Onsite Wastewater Disinfection and Nutrient Removal for Safe Discharge and Reuse [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588070537771

    APA Style (7th edition)

  • Liu, Kun. Improved Onsite Wastewater Disinfection and Nutrient Removal for Safe Discharge and Reuse. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588070537771.

    MLA Style (8th edition)

  • Liu, Kun. "Improved Onsite Wastewater Disinfection and Nutrient Removal for Safe Discharge and Reuse." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588070537771

    Chicago Manual of Style (17th edition)

osu1500588070537771
603
© 2017, some rights reserved.Creative Commons License Improved Onsite Wastewater Disinfection and Nutrient Removal for Safe Discharge and Reuse by Kun Liu is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.