Use of supervisory, control, and data acquisition (SCADA) system for monitoring, supervision and controlling of pumping systems can help minimize energy consumption of GHG emissions. It includes measurements in real time of water levels, pressures, flows, energy consumption and other operational parameters. It also helps to adjust and control the pump station operation, contributing to fight water losses or infiltration, reduce pumping during energy peak hours and adjust pumping volumes to the needs of the system. The SCADA systems provide utility managers with access to real-time operating data and can help offset the higher operating costs by minimizing unplanned downtime and improving maintenance plans. The SCADA system can also be used to optimize pumping in real-time through advanced pump optimization software and control, or through either a model-based or knowledge-based optimization that is implemented via a rule-based system programmed into the SCADA system. This type of optimization entails the use of algorithms to determine the best pumping scheme for a given situation. This can incorporate the peak energy times previously referenced, but also a prioritization of which pumps or pumping stations are used to maximize efficiency whenever possible. For example, if only a certain volume is demanded, then the SCADA system will first operate the most efficient pumps or pumping stations to meet the demand until greater capacity or more pumps are needed.
Based upon the system head conditions, pumps may be able to pump at higher rates than needed when operating at 100% motor speed. This flow rate can be controlled by one of two ways, throttling the pump with a valve if the pump is a constant speed pump, or changing the motor speed with a variable speed drive. The former is only energy efficient if the higher flow operating point of the pump without throttling is to the right of the best efficiency point on the pump performance curve, and the throttling results in reducing the flow to a point closer to the best efficiency point on the pump curve. Otherwise, throttling the pump can result in using more energy than at the higher flow, as well as wasting energy because you end up using more energy than is needed. When the demand on the system fluctuates significantly, the pumping rate can be controlled automatically by varying the speed of the motor with a variable frequency drive (VFD), such that the pump output matches only what is needed to meet demands or the intended pumping conditions. The pump’s flow rate then increases or decreases based upon the affinity laws and the controlled speed of the motor. This way lower pumping rates can be achieved, which may result in lower efficiency than those at full motor speed; however, the energy consumption is still lower because the energy requirements to pump lower flows at lower heads are lower.
Planificación local, impacto global – Como las Empresas de Agua y Saneamiento del Perú enfrentan el Cambio Climático
¿Cómo asegurar la prestación de los servicios de agua y saneamiento en un contexto de cambio climático? Los Planes de Mitigación y Adaptación al Cambio Climático (PMACC) son una herramienta para abordar este desafío. Permiten identificar las principales fuentes de emisiones de carbono y los mayores riesgos asociados al clima a lo largo del ciclo urbano del agua; así como las oportunidades de las empresas prestadoras de servicios de agua y saneamiento (EPS) para impulsar un cambio positivo hacia la neutralidad y adaptación climática. Siguiendo una metodología estandarizada y con la ayuda de herramientas virtuales, el proceso de planificación es más rápido y genera un reporte para informar a los tomadores de decisión. Gracias a esta buena planificación, algunas empresas del Perú han empezado a buscar soluciones prácticas para reducir sus emisiones de carbono, como es el caso de las empresas de agua de Cusco y Ayacucho. La iniciativa PMACC fue desarrollada e implementada en colaboración entre WaCCliM (responsable de la parte de mitigación) y PROAGUA II.
Planning locally, impacting globally – How Water and Wastewater Utilities in Peru are Facing Climate Change
How to ensure water and sanitation services delivery under a climate change context? The climate change mitigation and adaptation plans (PMACC; Planes de Mitigación y Adaptación al Cambio Climático) are tools to address this challenge. PMACC identify main carbon emissions sources and higher climate risks throughout the urban water cycle, along with water utilities’ opportunities to boost a positive change towards climate neutrality and adaptation. Following a standardised methodology and supported by web-based tools, the planning process becomes quicker and generates a report to informing decision-makers. This planning approach enabled some water utilities in Peru to start searching for practical carbon emissions reduction solutions, such as water utilities in Cusco and Ayacucho. The PMACC initiative was developed and implemented collaboratively between WaCCliM (responsible for mitigation) and PROAGUA II.
A greenhouse gas (GHG) calculator tool (Biosolids Emissions Assessment Model, BEAM) was developed for the Canadian Council of Ministers of the Environment to allow municipalities to estimate GHG emissions from biosolids management. The tool was developed using data from peer-reviewed literature and municipalities. GHG emissions from biosolids processing through ﬁnal end use/disposal were modeled. Emissions from nine existing programs in Canada were estimated using the model. The program that involved dewatering followed by combustion resulted in the highest GHG emissions (Mg CO2e 100 Mg-1 biosolids (dry wt.). The programs that had digestion followed by land application resulted in the lowest emissions (-26 and -23 Mg CO2 e100 Mg-1 biosolids (drywt.). Transportation had relatively minor effects on overall emissions. The greatest areas of uncertainty in the model include N2O emissions from land application and biosolids processing. The model suggests that targeted use of biosolids and optimizing processes to avoid CH4 and N2O emissions can result in signiﬁcant GHG savings.
In San Francisco del Rincón, two utility companies, SITRATA (Servicio de Tratamiento
y Deposición de Aguas Residuales) and SAPAF (Sistema de Agua Potable y
Alcantarillado de San Francisco), are collaborating on projects to improve their
services and lower their greenhouse gas (GHG) emissions. SITRATA manages
wastewater, while SAPAF is responsible for drinking water and sewage. With
guidance from the WaCCliM project, both utilities have undertaken a strategizing and
implementation process similar to that proposed in the “WaCCliM Roadmap to a Low-
Carbon Urban Water Utility”.
As a result, SAPAF have increased wastewater treatment coverage from 48% to 81%
and improved the energy efficiency of their pumping stations. The magnitude of the
increase in treatment coverage was by far the biggest achievement in GHG reduction.
In Madaba, the Miyahuna Water Company conducted a study to determine and
address greenhouse gas (GHG) emissions from its operations. Miyahuna operates
both water and wastewater systems in the city. The GHG assessment was conducted
using the Energy Performance and Carbon Emissions Assessment and Monitoring
(ECAM) Tool. This highlighted that 90% of energy consumption is linked to the
extraction of drinking water.
In order to decrease the utility’s carbon footprint, several GHG reduction measures
were evaluated. However, some are difficult to implement due to financial constraints.
The most feasible option was the improvement of the pumping system. This would
reduce annual electricity consumption by 35–50%.
In the city of Chiang Mai, the WaCCliM project supports the Wastewater Management
Authority (WMA) in assessing opportunities to reduce its carbon footprint. A baseline
study identified the leaks of untreated wastewater, caused by fractured pipes in the
wastewater collection system, as the main source of greenhouse gas (GHG) emissions
in Chiang Mai. A large amount of untreated wastewater is flowing directly into the
public canal. Because of this, the city is producing significant amounts of methane
(CH4) and nitrous oxide (N2O), both gases with a larger global warming potential than
carbon dioxide (CO2). The emissions from direct discharge of untreated wastewater
account for 579,900 kg CO2 per year in the city.
The cooperation between WaCCliM and the WMA in Thailand has raised the
local awareness for the challenges in the wastewater sector and the need for
improvements in the urban water management in order to achieve resilient water
utilities. Therefore, knowledge transfer and capacity building are necessary for longterm
success and continuous progress.
The Water and Wastewater Companies for Climate Mitigation (WaCCliM) project aims to improve the efficiency of water and wastewater companies in Mexico, Peru, Thailand, and Jordan, reduce their greenhouse gas (GHG) emissions, and improve the carbon balance of the water sector, while maintaining and/or improving service levels. As part of the project, hydraulic modelling software was used to simulate the Cusco, Peru drinking water transmission system and evaluate various scenarios (water loss reduction, pump replacement, and system reconfiguration) and their energy impacts. Results showed the transmission system’s pumping energy could be reduced up to 40 percent depending on the scenario. A holistic view on the total urban water cycle has also helped to identify that a combined effort to conserve water at the end user level, reduce water loss, reuse water, and rainwater harvesting will ultimately make the biggest impact on the transmission system’s energy consumption and GHG emissions, and lead to the most sustainable and resilient urban water management for SEDACUSCO and the City. This study has also demonstrated that water distribution system models can play an invaluable role in water utility climate change mitigation and adaptation planning.
The objective of this technical note is to inform utility managers and technical decision makers in East Asian countries about appropriate technologies available for wastewater treatment with energy recovery processes.