Summary:As global environmental issues become increasingly prominent, low-carbon and eco-friendly practices have become a shared goal worldwide. As a key facility in urban environments, the lighting system of underground wastewater treatment plants plays a crucial role in energy conservation and environmental protection. The article takes a specific underground wastewater treatment plant as an example to analyze lighting system design, including the selection of lighting fixtures, the application of green energy, and the requirements for intelligent lighting control. It also proposes solutions to reduce carbon emissions and energy consumption in underground wastewater treatment plants, achieving the goal of green and low-carbon lighting design.
KeywordsLow-carbon and environmental protection; underground wastewater treatment plant; lighting system design; intelligent control
Introduction
As urbanization accelerates and the population grows, the importance of underground wastewater treatment plants becomes increasingly evident. Limited by urban planning, land utilization, and natural environment factors, underground or semi-underground wastewater treatment plants have become a new direction in urban wastewater treatment planning. However, due to the lack of sunlight and natural light, underground wastewater treatment plants often lead to higher operational costs. Therefore, the optimized design of the lighting system is particularly important in electrical design.
Currently, in the face of increasingly severe climate change and environmental issues, our country has successively issued a series of building energy-saving standards, and the National Development and Reform Commission has formulated the "Medium- and Long-Term Special Plan for Energy Saving." These specifications and standards clarify the direction of energy-saving design for residential buildings. However, modern underground or semi-underground sewage treatment plants differ from residential buildings, and only targeted analysis and design can be conducted for them.
By adopting innovative technologies, the underground wastewater treatment plant's lighting system has been enhanced in energy efficiency and environmental sustainability, reducing energy consumption and lowering carbon dioxide emissions, thereby achieving the goal of energy and emission reduction.
Underground Sewage Plant Lighting Requirements
2.1 Luminous Intensity
Underground wastewater plants require adequate lighting to ensure clear visibility for staff and operational safety. The level of illumination varies depending on the type of work area (such as offices, workshops, pipelines, etc.) and requirements, and is typically set according to national or local standards.
2.2 Color Temperature and Color Fidelity
Underground wastewater treatment plant workplaces require appropriate lighting to ensure good visual effects and comfort. Color temperature refers to the hue of light, such as cool tones and warm tones, and should be set according to the needs of the workplace. Color fidelity refers to the light source's ability to accurately reproduce the color of objects, and operations sensitive to color, such as detection and analysis, require the light source to have high color fidelity. Additionally, the choice of light sources should comply with the regulations on energy efficiency grades in the "Energy Efficiency Grades for LED Products Used for Indoor Lighting" (GB30255—2019).
2.3 Uniformity of illumination
The underground space of the wastewater treatment plant is substantial, necessitating an even distribution of light to prevent certain areas from being too bright or dim, which could impact operational effectiveness and employee eye health. Appropriate control systems must be installed in the lighting system of the underground wastewater treatment plant to achieve automated control and adjustment of lighting. These systems should flexibly modify lighting brightness and color temperature based on varying times and workplace needs, thereby achieving energy savings and efficiency improvements.
Design of Low-Carbon Lighting System for a Subterranean Sewage Treatment Plant
3.1 Project Overview
The research focuses on a large underground wastewater treatment plant project in Yinchuan City, with a scale of 300,000 tons per day. The underground operational level includes areas such as biological pools, dosing rooms, odor control systems, and secondary sedimentation basins, designed as a single-story industrial building. Taking the secondary sedimentation basin area as an example, it measures 140m in length, 75m in width, and 6.5m in height, with standard column spacing at 9.3m×7.5m. One calculation unit consists of 12 standard units, which is a space of 37.2m in length and 22.5m in width for lighting calculation and arrangement, as shown in Figure 1. The lighting design installation height is 6.0m, with the working surface at ground level.
3.2 Design of General Lighting Systems
3.2.1 Lighting Selection
The design of the underground wastewater treatment plant's lighting system should align with the actual needs of the plant. To achieve a low-carbon concept throughout the entire process of procurement, operation, and maintenance of the lighting system, LED lighting fixtures are used in all areas such as the comprehensive building, factory buildings, and roads. LED lights offer high efficiency, strong controllability, long lifespan, low heat, and environmental friendliness, meeting the current low-carbon requirements for lighting applications.
LED lighting consumes less energy, providing higher luminosity and superior lighting effects, thereby reducing energy consumption and operational costs. LED lights can be precisely controlled through digital control systems, allowing for adjustable brightness and color temperature, enabling automated and remote control to meet the needs of different times and work environments. They can achieve intelligent controls such as timed on/off and light sensing, enhancing lighting efficiency and energy efficiency ratio. LED lights have a longer lifespan, maintaining high brightness and stability for a longer period, reducing the frequency and cost of replacing lights, and lowering maintenance expenses for underground wastewater plants. Environmentally friendly, LED lights contain no harmful substances like mercury or lead, posing no pollution to the environment. They also have a high energy efficiency ratio, reducing carbon emissions and energy consumption, aligning with green and low-carbon lighting design concepts.
3.2.2 Lighting Arrangement
Utilize the coefficient method to calculate the number of lighting fixtures.
In the formula: N is the number of lighting fixtures; Eav is the average illuminance on the working surface, lx; A is the area of the working surface, m²; Φ is the luminous flux of the light source, lm; K is the maintenance factor of the lighting fixture; U is the utilization factor of the lighting fixture.
The design area is the operational zone of an underground sewage treatment plant, a frequently accessed area. According to the "Code for Design of Building Lighting" (GB50034—2013)[1], the standard illuminance value is set at 100lx, i.e., Eav=100lx. The working surface area A is 37.2m x 22.5m = 837m². Due to the environment's general characteristics of indoor contamination, the maintenance factor K is taken as 0.7.
Regarding the coefficient U, it is necessary to first calculate the room air distribution index (RI), with its calculation formula being:
In the formula: RI stands for Room Index; a represents the length of the calculation unit; b represents the width of the calculation unit; c represents the working surface height; and h represents the installation height of the lighting fixture.
With a ceiling reflectance ratio ρc of 0.3, wall reflectance ratio ρw of 0.5, and floor reflectance ratio ρf of 0.2, the average surface reflectance ratio ρ is calculated to be 0.3922, leading to an effective space reflectance ratio ρeff of approximately 0.1. Referring to the product manual, at a reflectance index (RI) of 2.00, the U-value is 0.78; at RI 2.50, U is 0.83. By interpolation, when RI is 2.337, U is determined to be 0.8137. According to the product manual, a 95W LED factory light with a luminous flux Φ of 11400 lm is selected. Therefore, the number of lamps is determined. Considering the calculation unit area consists of 12 standard units, one 95W LED factory light is installed per standard unit.
3.2.3 Plan Verification
*Maximum Allowable Aspect Ratio. According to the Lighting Design Handbook (3rd Edition) [2], when selecting lamps with a wide distribution, the maximum allowable aspect ratio LH is:
In this formula: L represents the distance between the centers of the light sources of the lamps, in meters; H is the suspension height of the lamps, in meters. In the longitudinal spacing of the factory, one lamp is set every 7.5 meters, and one lamp is set every 9.3 meters in the transverse spacing. The lamps are evenly distributed, resulting in a longitudinal height-to-distance ratio of 7.5/6 = 1.25 and a transverse height-to-distance ratio of 9.3/6 = 1.55, both ratios meet the requirements.
The actual illuminance value is calculated to be 93.1 lx, meeting the specification requirement that the deviation from the standard illuminance value does not exceed ±10%.
Power Density Value. The power density value is calculated as 12×95÷(37.2×22.5) ≈ 1.36 W/m², meeting the energy-saving standard requirements.
Application of 3.3 Optic Lighting Technology
A low-carbon and environmentally friendly photovoltaic lighting system has been designed in the treatment area of the wastewater plant's building, as shown in Figure 2. The system utilizes outdoor natural light as the light source, efficiently transmitting the light indoors through special transmission devices. To achieve ideal underground space lighting effects, a luminance analysis is required.
In accordance with process requirements, an additional access corridor for daily inspections by waterworks staff should be designated within the operational space of the underground wastewater treatment plant. This corridor is equipped with automated instruments, local control stations, and local control cabinets, enabling on-site equipment control and instrument monitoring. Considering the high initial cost of the light-conducting tubes in optical fiber technology, to achieve a win-win situation for social and economic benefits, the light-conducting tubes are only installed in the inspection corridor of the underground operational space.
The wastewater treatment plant is located in Yinchuan, Ningxia, which falls under Climate Zone II in China. According to the "Standard for Design of Natural Lighting for Buildings" (GB50033—2013)[3], the outdoor natural light design illuminance value Es is 16500 lx. In the calculation unit area, the inspection passage is 55.8m long and 4m wide, with a lighting area A of 223.2m². Based on the manufacturer's data, the diameter of the light guide tube is 900mm, with an area At of 0.64m², and a system efficiency η of 0.723. Therefore, the designed output luminous flux Φ of each light guide tube is Φ = Es × At × η = 7635 lm. The room space ratio, calculated based on the inspection corridor, is 8.7. After consulting the table and using interpolation, the lighting utilization coefficient U is 0.50, and the maintenance coefficient K is 0.8. Consequently, the average illuminance in the light guide lighting area is
。
The luminance in the light guide illumination area exceeds the standard value of 75lx, meeting the requirements. When selecting equipment for the light guide, it is necessary to meet the design requirements of the diffuser, ensuring the full angle is controlled at 37° or more.
By implementing fiber optic lighting technology, the underground sewage treatment plant has achieved zero energy consumption, no maintenance, low cost, and a natural, comfortable environment during daily operations. Fiber optic lighting largely replaces electrical lighting during the day, reducing the energy consumption for daytime lighting within the plant and indirectly lowering emissions of carbon dioxide and other pollutants. The hollow interior of the light guide tubes eliminates the need for regular replacement of lighting fixtures; with only the need to wipe the采光 devices, maintenance is truly minimal. Furthermore, the light source of the fiber optic technology is derived from sunlight, providing soft, full-spectrum, flicker-free light with excellent color rendering, which can reduce visual fatigue and make the work environment more comfortable.
3.4 Application of Smart Lighting Control Technology
Smart Lighting Control Technology is a method that achieves lighting automation through perception and control technologies. In underground wastewater treatment plants, this technology can help achieve more intelligent and efficient lighting control, resulting in energy saving, comfort, and environmental protection. The smart lighting control system in underground wastewater treatment plants consists of a lighting control computer, several lighting control modules, as well as lighting control panels, illuminance sensors, infrared sensors, etc. The lighting control computer is located in the control room of the plant's comprehensive building, responsible for controlling and managing the entire smart lighting control system, with each lighting control module installed in the lighting distribution boxes of respective zones. The system uses a real-time and reliable communication bus to send network control commands to the lighting control modules and simultaneously receive manual/automatic working status, lamp switch status, and fire automatic alarm联动 signals from the site. Lighting control panels and infrared sensors are installed at the main entrance and exit points of indoor areas, allowing on-site switching of lighting modes and lamp operation, maximizing energy savings in the lighting system. By establishing a smart lighting control system, functions such as brightness sensing, time control, and remote control are achieved, helping the underground wastewater treatment plants to realize more intelligent, efficient, comfortable, and environmentally friendly lighting control.
Features of the Underground Sewage Plant's Low-Carbon Lighting System
The application of low-carbon lighting systems in underground wastewater treatment plants can achieve goals such as energy and carbon reduction, long lamp lifespan, high color fidelity, and ease of control, all while reducing energy consumption and carbon emissions. However, it is undeniable that there are still some drawbacks to the use of low-carbon lighting systems.
4.1 Initial costs are high.
LED lighting systems and other energy-efficient sources used in low-carbon lighting systems have higher initial costs, which increase the equipment's upfront investment, but they offer returns in terms of lifespan and energy savings.
4.2 Requires professional installation and maintenance.
The installation and maintenance of low-carbon lighting systems require professional technical personnel, such as adjusting and installing light sources. In case of any issues, professional repair or replacement is needed, which increases costs and maintenance difficulties.
4.3 Insufficient illumination.
The light source brightness of low-carbon lighting systems is lower than that of traditional lighting equipment, requiring more LED sources to achieve the same illumination level as traditional lighting, which increases the number and cost of the equipment.
5AcrelEMS-SW Smart Water Efficiency Management Platform
5.1 Platform Overview
AcrelEMS-SW Smart Water Efficiency Management Platform, part of Acrel's comprehensive product ecosystem ranging from terminal perception to edge computing and energy efficiency management platforms, is designed to monitor the total and intensity of energy consumption in wastewater treatment plants. By installing protective, monitoring, analytical, and treatment devices at critical nodes such as sources, networks, loads, storage, and charging, the platform focuses on the energy efficiency of major energy-consuming equipment. It ensures the safe and reliable operation of wastewater treatment plants, enhances their energy efficiency, and provides a scientific and precise solution for energy efficiency management in wastewater treatment.
5.1.1 Platform Composition
The AcrelEMS Smart Water Utility Comprehensive Energy Management System is composed of a substation integrated automation system, power monitoring, and energy management. It encompasses medium-voltage distribution and transformation systems, electrical safety, emergency power supply, energy management, lighting control, and equipment maintenance, covering the entire water utility energy flow. It assists facility managers in real-time monitoring the operation of the water distribution system through a single platform and an APP, and can be applied to the management needs of water utility support departments based on user permissions.
5.1.2 Platform Topology Diagram
5.2 Platform Subsystem
The system provides lighting control management solutions for wastewater treatment plants, waterworks, pump stations, etc., supporting various control methods such as single control, area control, automatic control, sensor control, timer control, scene control, and dimming control. The modules can automatically identify sunrise and sunset times based on latitude and longitude to enable automatic control functions, maximizing the use of natural light to achieve intelligent indoor and factory area lighting for safety, energy efficiency, comfort, and efficiency.
5.3 Emergency Lighting and Evacuation Guidance
The emergency evacuation plan was swiftly initiated according to pre-established protocols, guiding personnel in their疏散. The system integrated with the fire emergency lighting indicator system data, displaying the operational status and any anomalies of the evacuation lighting fixtures on a floor plan.
Fire Equipment Power Supply Monitoring
Monitor the operational power of fire protection equipment to ensure normal operation in the event of a fire.
6 Conclusion
The article, based on an analysis of low-carbon lighting technology and combined with the actual needs of underground wastewater treatment plants, designs a low-carbon lighting system. This system employs low-carbon lighting technologies such as LED, light guides, and intelligent lighting controls, achieving smarter, more efficient, and comfortable lighting. We believe that in the near future, low-carbon lighting technology will be applied in a wider range of scenarios, creating a more beautiful lighting environment for humanity. Through the summary of experience in lighting design for underground wastewater treatment plants and research on regulations, an effective and targeted lighting design method has been developed.
References
- Long Chengchao: Design and Application of Low-Carbon Lighting System for Underground Sewage Treatment Plants
- China Academy of Building Research. Standard for Building Illumination Design: GB50034—2013[S]. Beijing: China Architecture & Building Press, 2014.
- Beijing Lighting Society, Lighting Design Professional Committee. Lighting Design Handbook (3rd Edition) [M]. Beijing: China Electric Power Press, 2017
[4] AnkoRe Enterprise Microgrid Design and Application Handbook. 2022.05 Edition
