Climate smart utilities – China rises to the carbon challenge

Chongqing Wastewater Treatment Plant

Showcasing five Chinese cases among the global utilities recognised by IWA’s Climate Smart Utilities Initiative.

IWA’s Climate Smart Utilities Recognition Programme seeks to inspire water, wastewater, and urban drainage utilities to be innovative in their response to the climate challenge and their actions across three interconnected pillars for action: climate adaptation, mitigation, and leadership. Utilities around the world were recognised at a special ceremony in Copenhagen last year and utilities from China secured a number of successes. Here we provide a round-up of this work by Chinese utilities to drive down carbon emissions and build climate resilience into their operations.

Beijing Capital Eco-Environment Protection Group

The Beijing Capital Eco-Environment Protection Group has provided services to more than 100 cities in China, with a water treatment capacity of 25 million tons/day, servicing a population estimated at more than 80 million at the end of 2021.

As a leader in China’s water sector, the group has a systematic action plan for carbon emissions reduction, excellent operation and management capabilities, sustainable and low-carbon innovative technologies, and smart digital platforms. The group has adapted to climate challenges by promoting energy recovery, reducing greenhouse gas emissions, and working to become a climate smart public water utility by investing in adaptation and mitigation measures.

Between 2019 and 2021, the group carried out an internal carbon inventory to identify how it could reduce its greenhouse gas emissions. This was the first time that a Chinese water and environmental protection enterprise had conducted a systematic carbon inventory and independently developed a carbon footprint model for wastewater treatment. This has improved the accuracy of carbon accounting in the utility and is considered the first carbon footprint accounting model for municipal water systems in China.

The group has actively developed low-carbon technologies, including research into applications for aerobic granular sludge, and proprietary ASMART technology based on biological modelling to achieve carbon emissions reductions at the source. Other technologies, such as replacing traditional thermal power with clean energy, including the use of wastewater source heat pumps and photovoltaic (PV) technology, digital management platforms, and the reduction of electricity and chemical consumption, are part of the group’s goal to reduce greenhouse gas emissions.

To cope with the impact of extreme climate change, the group has developed a set of resilient urban drainage system strategies to deal with extreme rainfall events through real-time management of wastewater treatment plants (WWTP), pipelines, and rivers.

The company has also issued technical guidelines to reduce leakage through a GIS management platform, the control of pipe quality, water balance calculations, and water meter verification. In 2021, the company’s overall water supply production and sales gap dropped to 14.13%, a decline for five consecutive years.

As a leader in China’s environmental protection industry, the Capital Eco-pro Group works to actively improve its stakeholders’ awareness of the impacts of climate change.

The group aids China’s drive for carbon neutrality and provides free, independently developed carbon footprint accounting software for WWTPs and promotes the reduction of carbon emissions from domestic public utilities.

Capital Eco-pro Group will continue to strengthen its carbon data and asset management formular and develop low-carbon technologies to achieve the goal of peak carbon by 2030 and carbon neutrality by 2060.

Chongqing wastewater treatment plant

With more than 30 million residents, Chongqing is the largest and most populous municipality in China. Aiming to evolve as a climate smart, resilient city, Chongqing has partnered with Suez since 2002. This Public-Private-Partnership (PPP) model has expanded from water supply to wastewater treatment, environmental services for industrial parks, and R&D.

As early as 2021, Chongqing wastewater treatment plant (WWTP) was rated as a benchmark WWTP by Water China’s E20 environmental service platform for its operational management and accurate control of key processes, becoming a demonstration WWTP for smart water and sustainable development.

As part of the development of its smart water initiative, the utility integrates Programmable Logic Controller (PLC) platforms within its plant production to create a unified visual monitoring system, utilising a simulation model and integrating multiple sub models (such as precise aeration and dosing) to save energy and reduce carbon emissions. An accurate offline model has been developed to provide simulated effluent results, which combined with actual operation effluent results, guide production in real-time, and enable production problems to be predicted and resolved.

Innovative projects to save energy include flow field analysis and optimisation of agitator operations, reuse of backwash water and dewatering liquids, the replacement of ventilators with unpowered fans, and an energy management platform that optimises energy throughout the plant.

The use of new sand water separation and carbon source recycling technologies has increased the removal rate of inorganic substances by 40%. It also reduces equipment wear and subsequent processing loads, saving 10,000 kWh of electricity per year.

Most recently, Computational Fluid Dynamics (CFD) simulation software has been applied to simulate the flow field of a biological pool with the aim of reducing energy consumption. Analysis of the automatically operated agitator found a saving of approximately 5250 kWh/d of electricity, saving energy by nearly 30% and reducing carbon emissions by approximately 1100 tons/year.

Through these efforts the utility has improved its energy self-sufficiency by about 30% annually, with an annual carbon emission reduction of more than 20,000 tons.

As a result of initiatives based on global climate commitments and the Suez sustainable development plan, the WWTP’s energy self-sufficiency rate is expected to rise to 70% sustainable electricity.

Further developments to be achieved by December 2025 include:

  • The expansion of outlet water power generation (expected to increase generation by 50%).
  • Optimisation of the anaerobic digestion process to produce biogas (increasing biogas output to 20,000 m3/d).
  • The application of water source heat pump technology and photovoltaic (PV) power generation to achieve 10,000 kWh/d from PV.
  • A sludge terminal reduction process which includes deep dewatering and low temperature drying, multi-stage furnace online incineration, ultra-high pressure pressing, dewatering, and deep filtration dewatering.

Beijing Drainage Group

Beijing Drainage Group (BDG) is a state-owned wastewater utility that owns and operates 11 treatment plants in Beijing with a combined capacity of 4,230,000 m3/d. BDG manages more than 10,000 kilometres of pipe networks and auxiliary pumping stations serving 17 million people.

Thermal hydrolysis © Beijing Drainage Group

BDG unveiled a three-step carbon neutrality roadmap in 2021, with the aim of reducing its current carbon emissions (450,000 tons of CO2/year) and carbon intensity (3.6 tons of CO2 per 10,000 m3 of wastewater treated) sequentially by 20% in 2025 and by 40% in 2035, before hitting net zero in 2050.

BDG has taken major steps to become China’s first carbon neutral utility by 2050.

Its distributed solar photovoltaic (PV) systems realised around 23 million kWh in 2022, making the group the top producer of solar energy in China’s municipal wastewater sector. The group completed the construction of a 1.62 MW PV system at Gao’antun wastewater treatment plant (WWTP) in 2022 and plans to use the technology in all of its plants by 2025.

BDG has also completed biogas power generation facilities at its sludge centres, which is expected to produce 80 million kWh of power a year, meeting around 20% of the power demand for the group.

Gao’antun WWTP is set to become fully self-sufficient in terms of electricity and carbon neutral using diversified renewable energy.

In 2022, the group applied self-developed aerobic granular sludge technologies to replace the traditional activated sludge process in its 80,000 m3/d Wujiacun WWTP.

BDG’s five sludge treatment centres, with a combined capacity of more than 1200 tons of dry solids per day, uses an advanced solution with thermal hydrolysis and anaerobic digestion.

The group’s smart system allows aeration, chemical dosing, pumping and other processes to be controlled in an extremely accurate and predictive manner. Compared with 2020, the power consumption of sewage treatment, the carbon source dosing rate and phosphorus removal dosing rate have been reduced by 11%, 30% and 10%, respectively.

Macao Water Supply Company

The Macao Water Supply Company, a subsidiary of Suez established in 1935, is a private enterprise in Macao SAR of China dedicated to providing safe, stable, and quality water supplies to the city.

Located in southern China, Macao is surrounded by sea on three sides. In recent years climate extremes have become a challenge to water security and Macao Water has taken various measures to address this.

In response to the climate challenge, floodgates and watertight doors protect core water supply facilities from typhoons and storm surges. The company has an emergency mechanism and a set of digital applications for effective and efficient responses to extreme weather events and works with government departments and the raw water supply company in Macau SAR and Zhuhai, a city connecting Macau to mainland China.

In terms of energy conservation, Macao Water has obtained ISO 50001 energy management certification and sets energy-saving targets annually. Business intelligence reports are recorded based on collected electricity and chemical consumption data and used to optimise energy consumption. Other green measures include the gradual replacement of fuel vehicles, pilot projects for solar power generation, and digitisation of the firm’s operations.

In environmental leadership, the company organises open days for the public. It has also launched a three-year subsidy programme to encourage homeowners of low-rise buildings to maintain shared water supply facilities. The firm promotes electronic payment methods and is gradually installing smart water meters to customers.

Having formed its Crisis Management Committee a decade ago, the company organises regular drills. In 2017, typhoon Hato resulted in the submergence of one of the city’s main pumping stations. Following this, the company reviewed its emergency plan, and installed floodgates and watertight doors to protect its water supply facilities. Digital applications have also been utilised to improve typhoon emergency management.

Saltwater intrusion is also a threat to Macao’s water supply, as its raw water is downstream of the Pearl River in Zhuhai. By cooperating with the Macao SAR government and Pearl River Water Resources Commission, a new raw water intake for Macao was built further upstream to secure the raw water supply for drinking water. The company is also working on a reclaimed water plant, which aims to be in service in 2024, to supply a new zone of the city with water to be used for greening the environment and toilet flushing.

A further project will see cameras and water quality monitoring instruments with AI intelligence fitted on unmanned boats used to inspect reservoirs remotely. This will enable matters of concern, such as dead fish or debris in lakes, to be identified swiftly, and help laboratory personnel understand trends in water quality.

Shanghai Chemical Industry Park

Shanghai Chemical Industry Park (SCIP) in Shanghai, China, is one of the largest petrochemical and fine chemical clusters in Asia.

In recent years, SCIP has been pursuing construction of a green, ecological, and low-carbon park, working hard to become a model zero carbon park for China and across the globe.

The SCIP Sino-French Water Development Company provides water and wastewater treatment services to the park and, from 2021, responded positively to national government and shareholder policies to establish a sustainable development task force to address climate change.

As a provider of industrial water and desalinated water to the park, the company focuses on saving water resources and reducing carbon emissions. In 2019, renovation of two water supply loop systems was completed to ensure a stable water supply and achieve the goal of diversifying the company’s water portfolio.

A smart network system is combined with Suez’s patented real-time hydraulic model to provide an early warning and forecasting system for the water supply network, along with real-time monitoring of water loss and non-revenue water in industrial and desalinated water supply networks.

The company encourages water saving by formulating water-saving incentive policies. The wastewater treatment plant (WWTP) is equipped with a 35,000 m3 buffer tank, emergency tank and bypass system to cope with severe fluctuation of water quality and quantity from upstream customers caused by climate change.

Part of the outlet water from the treatment plant is discharged into the SCIP ecological wetland for water quality purification. This nature-based solution functions as a carbon sink, reducing an estimated 2800 tons of carbon dioxide (CO2) emissions per year. The wetland expansion is expected to be put into operation in 2024.

The industrial water plant has photovoltaic panels (PV) to generate electricity for its administrative buildings and is expecting to reduce CO2 emissions by 800 tons per year. Further savings will be made by replacing surface aeration with bottom aeration, achieving CO2 reductions of 40%, about 700 tons of CO2 per year.

Other green solutions, such as the replacement of energy-consuming aeration blowers, the installation of PV panels in the wastewater treatment plant (WWTP), and the generation of hydrogen by electrolysing treated wastewater, are being considered in a feasibility study conducted by the R&D team.

Meanwhile, the company has carried out in-depth work with universities and scientific research institutes to promote CO2 emission management and has installed smart instruments and energy consumption monitoring systems to analyse the energy consumption of the WWTP through automatic data collection to provide reasonable optimisation suggestions.

Real-time CO2 monitoring equipment has been installed in the plant to provide a clear picture of its emission pattern.

The company’s achievements have become a model for SCIP and the wider water industry, helping the sector to respond to climate change through technical exchange and sharing via seminars, and online and offline lectures.

The organisation will continue to increase its investment in climate resilience and the reduction of CO2 emissions, including projects focused on wastewater reuse (2023 Q3), the replacement of energy-saving equipment (2024 Q4), and the expansion of PV technology in its water treatment plants (2025 Q4).

Article based on information provided by the respective cases.

For more information on IWA’s Climate Smart, please see:

Find out about the results of the 2023 CSU Recognition Programme here: