Identification of Sustainable Alternative Applicable to North Engineering Toilets
Identification of the Most Sustainable Alternative System to be used for Toilets in North Engineering Building of University of Toledo: A Comparative Study of Implementation of Rain Water Harvesting, Grey Water Recycling and Composting Toilets
By
Akhil Kadiyala
Zheng Xue
Andrew E. Wright, LEED A.P.
Table of Contents
1. Abstract 5
2. Introduction 5
2.1 Economic Input output Life Cycle Assessment (EIOLCA) 7
2.2 Indicators 8
2.3 Sustainability Index and Performance Percentage 9
2.4 LEED Requirements 10
3. Data Collection 10
3.1 Data collected from Maintenance Department and Survey 11
3.2 Data collected for Life Cycle Inventory of Life Cycle Assessment 13
4. Design of Alternative Systems 13
4.1 Rainwater Harvesting 14
4.2 Grey Water Recycling 17
4.3 Composting Toilets 22
5. Results 25
5.1 LCA Results 26
5.2 Indicator Analysis Results 27
5.2.1 Environmental Pollution Indicator 28
5.2.2 Natural Resource Consumption Indicator 29
5.2.3 Economic Indicator 30
6. Sustainability Index and Performance Percentage 32
7. LEED Credits 32
8. Conclusion 33
9. References 34
Appendix A 37
Appendix B 44
List of Figures
Figure 2.1.1: System Boundary of LCA 7
Figure 2.1.2: Inputs-Outputs of construction and O&M phases 8
Figure 4.1 - Graph of present water consumption in restrooms 14
Figure 4.1.1: Concept of Rainwater collection system 15
Figure 4.2.1: Concept of Living Machine System to be used at UT. 21
Figure 4.3.1 - Clivus Multrum M18 24
Figure 4.3.2 – Schematic of composting system 24
Figure 5.1: Water use Consumption and Waste Water Effluent 26
Figure 5.1.1: Greenhouse gases for “Construction” and “O&M” Stages of a Life Cycle 27
Figure 5.1.2: Energy for “Construction” and “O&M” Stages of a Life Cycle 27
Figure 5.2.2.1: Average daily water savings (gal/day) for different systems 29
Figure 5.2.3.1: Economical Choice Comparison based on Cost of Construction and O&M 30
Fiigure 5.2.3.2: Economical Choice based on Cost/gal of water saved/day 31
List of Tables
Table 2.2.1: Indicators used for comparing the three systems 9
Table 3.1.1: Details of Restroom Fixtures in North Engineering Building 12
Table 4.1.1 – Rainwater Harvesting Estimate1 16
Table 4.1.2 – Rainwater Harvesting O&M 16
Table 4.2.1: Effluent characteristics as observed in universities 18
Table 4.2.2: Estimated Costs for Construction of Grey Water 22
Table 4.2.3: Annual Costs for Operation and Maintenance of Grey Water 22
Table 4.3.1 – Proposed Composting System for NE 25
Tables 5.2.1 – Water Consumption Analysis from EIO-LCA 28
Table 6.1: Sustainability Index and Performance Percentage Values 32
1. Abstract
This study compares the degree of sustainability and performance across three different systems that could be practically adopted by The University of Toledo (UT) to help conserve water for future generations. The systems considered were rainwater harvesting, greywater recycling and composting toilets. Over the last decade, the role of these three systems in reducing water consumption had been widely recognized across the world and many buildings are currently using these systems either individually or in combinations. While all three systems are capable of reducing the potable water usage in toilet flushing in North Engineering (NE) building of UT, each system has its own method of water conservation. Rainwater harvesting uses the collected rainwater as an additional source of supply for toilet flushing while greywater treatment enables the reuse of treated greywater from university for toilet flushing. Composting toilets reduce the water consumption as they consume minimum amount of water per flush and no water in some cases. None of the studies so far have compared these three systems that have different ways of conserving water from a sustainability point of view and this study aims at filling this knowledge gap.
This study provides two approaches of comparing these systems. Based on the LCA and indicator analysis performed by the group, it was inferred that composting toilets were found to be the most sustainable alternative system to reduce water consumption at UT. However, it is also preferable to have greywater recycling for maximum water conservation as the grey water produced by the university accounts for almost 35% total water consumed by university.
2. Introduction
The College of Engineering at The University of Toledo has proposed to renovate the North Engineering building in order to facilitate bringing all the students, faculty and administrative services within the main campus. The College of Engineering has heavily emphasized on the need to use sustainable alternatives during the renovation work. This project is being performed as part of evaluating the sustainable options of water use consumption for toilets and urinals in the North Engineering building that include the use of rain water harvesting, grey water recycling and composting toilets.
Rainwater harvesting has been used mainly for agricultural usage and landscape irrigation.It was found that rainwater harvesting has not been thoroughly studied in a sustainable aspect for its uses for water to be recycled through toilet and urinal flushing. Over the years, the number of studies that have focused on using recycled grey water for toilet flushing has been increasing and the standards for recycled grey water vary from one country to another. Lazarova et al. (2003) provided a comprehensive review of the various studies that have used recycled grey water for toilet flushing and documented the grey water quality criteria that needs to be adopted across different countries. The use of composting toilets has shown to reduce the amount of water needed and therefore reducing the amount of effluent going to waste water treatment plants (WWTP). There were no studies found that have focused on comparing the performance of these systems with respect to sustainability.
The overall objective of the study is to determine the most sustainable alternative system that can be applied to NE building at UT to reduce the water consumption, thereby identifying the possibility of obtaining LEED points for better management practices. The approaches used by the researchers in meeting the objectives are listed below and discussed in detail in subsequent sections 2.1-2.4.
1. Use ‘EIOLCA’ to determine the most suitable system by considering ‘construction’ and ‘operation and maintenance’ phases in a life cycle across the impact categories of greenhouse gases and energy.
2. Use different sustainable indicators as listed in Table 2.1.1 to analyze the performance of the systems.
3. Choose the most sustainable alternative system that could be adopted in toilets at the NE building based on sustainability index and performance percentage values.
4. Identify the possibility of obtaining LEED points for better management practices.
2.1 Economic Input output Life Cycle Assessment (EIOLCA)
EIOLCA was used to compare the three systems based on the economic inputs for each system obtained by designing of individual components for the systems and obtaining cost estimates for each component in the system. EIOLCA was used to identify the most sustainable alternative system from rainwater harvesting, grey water recycling, and composting toilets to reduce water consumption by toilets in NE block at UT using the phases of “Construction” and “Operation and Maintenance” across impact categories of greenhouse gases and energy.
Figure 2.1.1: System Boundary of LCA
Figure 2.1.1 presents the boundaries of the system adopted by the research group that is similar to the system boundary concept discussed by Memon et al. (2007). Only the construction and O&M phases are considered while transportation and energy required in material manufacturing and transport are neglected. To compare the three technologies we use the savings per life cycle of each system ($/life cycle) as a functional unit. It should be noted that only the raw materials for construction phase products will be considered but not the raw material extraction at manufacturing phase.
Figure 2.1.2 shows that the construction and O&M phases require the manufactured material and energy (electricity) as inputs for the three systems. The resulting outputs from these operations are atmospheric emissions, energy, and savings due to adoption of any of the systems. The life cycle assessment for these operations is performed using EIOLCA tool. Costs for manufactured materials for the different systems were obtained from online websites or open literature and are cited in the design sections. The energy consumption included electricity and the cost of electricity per kWh is taken as 5.6 cents that was taken from an electricity bill in Toledo.
Figure 2.1.2: Inputs-Outputs of construction and O&M phases
2.2 Indicators
Table 2.2.1 summarizes the type of indicators and their corresponding points used for comparing the three systems. Three different types of indicators namely economic indicator, natural resource consumption indicator and environmental pollution indicator are used to identify the most sustainable system from their perspectives.
Table 2.2.1: Indicators used for comparing the three systems
Type of Indicator / Points for comparisonEconomic / Determine economical choice for construction and O&M phases and calculate payback period for each system
Natural Resource Consumption / Compare the quantity of water saved by each system per day
Environmental Pollution / Determine the amount of greenhouse gases released and energy requirements for each system.
2.3 Sustainability Index and Performance Percentage
In order to compare the three systems, the points for comparison listed in Table 2.2.1 are used as a series of questions that were classified under economic, environmental and natural resource consumption indices. Points are allotted (‘3’ for best alternative, ‘2’ for intermediate alternative, and ‘1’ for last alternative) for each system for each question. If two systems have no relative advantages then both of the systems are given equal points for that particular question considered. The points are allotted based on the relativity rather than on absolute basis. The points are summed up in the end to provide a sustainable score to each of the systems considered. The best sustainable alternative system is then identified based on ‘Sustainability Index’ and ‘Performance Percentage’ calculated using equations 2.3.1 and 2.3.2 respectively.
….2.3.1
….2.3.2
where,
Performance percentage = Maximum Score of indicator × ∑Sustainable Score.
2.4 LEED Requirements
The U.S. Green Building Council's LEED Green Building Rating System establishes “best practice” criteria for water and energy usage that can be applied to any type of construction, even if certification is not the goal. The Water Use Reduction section of LEED-NC identifies a baseline for water use and awards one or two credits for surpassing requirements, in aggregate by 20 percent or 30 percent, respectively, beyond the Energy Policy Act of 1992 fixture performance requirements.
The categories that the research group analyzed for obtaining points in water conservation are listed below.
ü WE 2: Innovative Wastewater Technologies. The intent is to reduce generation of wastewater and potable water demand, while increasing the local aquifer recharge.
ü WE 3.1: Water Use Reduction 20%. The intent is to maximize water efficiency within buildings to reduce the burden on municipal water supply and wastewater systems.
ü WE 3.2: Water Use Reduction 30% has same intent as 3.1.
3. Data Collection
The data collected for the project can be divided into two categories. The first set of data was collected from the maintenance department, and also a survey of utilities in existing restrooms. This data helped to determine the existing water usage, and to predict water savings by adoption of alternative techniques. The second set of data was collected from various websites and open literature to estimate the quantity and costs of materials that would be used in the life cycle assessment.
3.1 Data collected from Maintenance Department and Survey
Preliminary information on water source and drainage systems was obtained from the maintenance department at UT. It was confirmed that only potable water obtained from Lake Erie provided by ‘The City of Toledo Water Treatment Plant’ is being used for all purposes including toilets at UT and there have been no recycling systems on campus. A monthly water bill for north engineering building revealed that the university was paying about $4277.00 for 1048 ccf (783,904 gallons). All of the waste water from toilets, sinks, sinks in labs, maintenance sinks and floor drains, and urinals are combined together before discharge and there are no provisions for separate discharges from sinks and toilets. In this study, we assume that 90% of this water is being released into the city’s sanitary system. An in depth comparison of each system is presented for its water reduction benefits and sustainability.
An initial survey was performed to find out the makes and model fixtures used in the restrooms of the north engineering building. The maintenance department could only provide information on the number of toilets in north engineering building and their floor plans. A walk through of existing facilities provided information on the number of fixtures and manufacturing company of the fixtures. The flow rates were obtained from online web search after getting the company and model numbers for the different fixtures. A summary of the restroom fixtures used in the North Engineering building are given in Table 3.1.1.
Table 3.1.1: Details of Restroom Fixtures in North Engineering Building
1262 / Faucets / 3 / Crane Plumbing / NA
Urinals / 2 / Zurn / 3.0 g/f
Toilets / 3 / Zurn / 1.6 g/f
1260 / Faucets / 2 / Crane Plumbing / NA
Toilets / 3 / Zurn / 1.6 g/f
2014 / Faucets / 3 / Kohler / NA
Urinals / 2 / Sloan / 1.6 g/f
Toilets / 3 / Sloan / 1.6 g/f
2013 / Faucets / 3 / Kohler / NA
Toilets / 5 / Sloan / 1.6 g/f
2053 / Faucets / 3 / Kohler / NA
Urinals / 2 / Sloan / 1.6 g/f
Toilets / 3 / Sloan / 1.6 g/f
2056 / Faucets / 3 / Kohler / NA
Toilets / 5 / Sloan / 1.6 g/f
1012 / Faucets / 3 / Kohler / NA
Urinals / 2 / Sloan / 1.6 g/f
Toilets / 3 / Sloan / 1.6 g/f
1013 / Faucets / 3 / Kohler / NA
Toilets / 5 / Sloan / 1.6 g/f
1055 / Faucets / 3 / Kohler / NA
Urinals / 2 / Sloan / 1.6 g/f
Toilets / 3 / Sloan / 1.6 g/f
1056 / Faucets / 3 / Kohler / NA
Toilets / 5 / Sloan / 1.6 g/f
0520A / Faucets / 3 / Kohler / NA
Urinals / 2 / Sloan / 1.6 g/f
Toilets / 3 / Sloan / 1.6 g/f
0600 / Faucets / 3 / Kohler / NA
Toilets / 5 / Sloan / 1.6 g/f
3.2 Data collected for Life Cycle Inventory of Life Cycle Assessment
The data collected for use in the EIOLCA that included parameters such as materials, quantities, and their respective costs were obtained from various websites and available open literature. Once the cost of construction and O&M were determined after a careful design of the individual systems, EIOLCA was used to perform the life cycle assessment.