New Opportunities for the MemPulse™ MBR Technology Following the Regulation Update on Wastewater Management in Mexico

The Mexican Official Standard NOM-001-SEMARNAT-1996 establishes the maximum permissible limits of pollutants in the discharge of wastewater into national waters and properties, as well as the technical specifications for their control and monitoring. On the other hand, the Mexican Official Standard NOM-001-SEMARNAT-2021 is the updated version of the previous regulation and establishes new provisions for the control and monitoring of the quality of wastewater, which recently came into effect.

One of the main differences between both regulations is the approach given to pollution prevention and control. NOM-001-SEMARNAT-1996 focuses on the maximum permissible limits of pollutants in the discharge of wastewater, while NOM-001-SEMARNAT-2021 establishes a comprehensive strategy for pollution prevention and control, which involves broader and more effective measures to protect the environment.

New Water Body Classifications

An important difference between both versions is the inclusion of new water quality classification criteria, allowing for better identification of areas that require pollution prevention and control measures.

The following table provides a comparison between both versions of the standard:

New list of contaminants:

Another important difference is that NOM-001-SEMARNAT-2021 incorporates new pollutants to the list of parameters to be monitored, in addition to establishing stricter values for several parameters. 

These changes are summarized in the following table:

^{(1) The values vary depending on the water body into which the treated water will be discharged. As such, it is recommended to review the values directly from NOM-001-SEMARNAT-2021.}

Requirements for Monitoring

Establishes stricter requirements for monitoring and measuring water quality, with the aim of ensuring that established quality standards are met. Regarding monitoring and measuring water quality, the NOM-001-SEMARNAT-2021 sets stricter requirements for sample collection and analysis, as well as for evaluating water quality. For example, criteria are established for selecting sampling points and the frequency of analyses, and calibration of measuring equipment and validation of analysis methods are required.

Design of Wastewater Treatment Plants and Sludge Management

The NOM-001-SEMARNAT-2021 also establishes more specific requirements for the design, construction, operation, and maintenance of wastewater treatment systems, with the aim of ensuring that these systems are more efficient and effective in removing contaminants. Additionally, new provisions are established for managing sludge generated by wastewater treatment, including the obligation to conduct a risk analysis for disposal and handling, and the establishment of preventive and corrective measures to minimize environmental impact.

Environmental Management

The NOM-001-SEMARNAT-2021 also establishes new obligations for water users, such as implementing environmental management programs and establishing preventive and corrective measures for pollution control. Likewise, greater demands are placed on reviewing and updating environmental management plans. Regarding environmental management, the NOM-001-SEMARNAT-2021 establishes the obligation of water users to implement environmental management programs, which must include preventive and corrective measures for pollution control, as well as periodic review and updating of environmental management plans. Additionally, criteria are established for selecting and applying wastewater treatment technologies and systems.

Regarding the application of standards, the NOM-001-SEMARNAT-2021 establishes a clearer and more comprehensive regulatory framework to ensure effective application of regulations. Additionally, stricter sanctions are established in case of non-compliance, which incentivizes water users to comply with the standards. The NOM-001-SEMARNAT-2021 also incorporates new requirements for the environmental impact assessment of wastewater discharges, which implies greater consideration of the possible effects of pollution on aquatic ecosystems and human health. In summary, the NOM-001-SEMARNAT-2021 is a more comprehensive regulation that sets stricter criteria for the prevention and control of pollution in wastewater discharges. The updated standard includes new provisions for environmental management, environmental impact assessment, and citizen participation, which allows for better protection of the environment and greater guarantee of the human right to water.

Solution:

This change calls for more advanced technologies that would allow to not only these stricter limitations but also give the opportunity to reuse the treated water. To that, DuPont™ Water Solutions offers MemPulse™ MBR technology. MBR (membrane bioreactor) technology is a type of wastewater treatment process that combines the biological process of activated sludge (ACS) with a membrane filtration system. This combination has several advantages, the main one being the use of membrane to improve the efficiency of the biological process by increasing the MLSS concentration. The MLSS (Mixed Liquor Suspended Solids) concentration is a measure of the concentration of microorganisms in a biological reactor. In traditional activated sludge processes, the MLSS concentration is typically limited by the settling characteristics of the mixed liquor. When the MLSS concentration is too high, the mixed liquor becomes more difficult to settle, leading to poor settling and carryover of solids into the effluent. This can result in a reduction in treatment efficiency and poorer effluent quality. On average, most standard ACS systems have an MLSS concentration ranging from 3,000 to 4,000 ppm.

In contrast, the use of a membrane in a biological reactor (MBR) allows for higher MLSS concentrations, which can range from 8,000 to 15,000 ppm, because the membrane acts as a physical barrier that retains the biomass within the reactor without needing the biomass to settle, it can remain in suspension. This retention of biomass allows for higher concentrations of microorganisms within the reactor, which leads to more effective treatment of the wastewater. The membrane filtration system in MBR technology provides a physical barrier that separates the mixed liquor from the effluent, allowing for higher MLSS concentrations to be maintained without affecting the quality of the effluent. The membrane also removes suspended solids, bacteria, and other contaminants from the effluent, resulting in higher quality effluent that can meet the stricter restrictions of the new standards and produce a quality that can be reused. 

Therefore, MBR technology is capable of maintaining much higher MLSS concentrations than traditional activated sludge processes, which can result in higher treatment efficiency and better effluent quality. This is because the membrane filtration system effectively removes solids from the mixed liquor, preventing them from interfering with the settling characteristics of the mixed liquor.

Other advantages MBR has over traditional activated sludge processes, include:

1. Space Efficient: MBR systems are more compact than traditional activated sludge systems. The membrane filtration system eliminates the need for a secondary clarifier, which reduces the overall footprint of the treatment plant. This is particularly beneficial in urban areas where land is at a premium. The elimination of the secondary clarifier allows for a smaller overall footprint, resulting in significant cost savings.

2. Resilient: MBR technology is more resilient to variations in influent quality and flow rate. The membrane filtration system provides a consistent level of treatment regardless of changes in the wastewater characteristics.

3. Fewer Chemicals: MBR systems require fewer chemicals for operation than traditional activated sludge systems. This is because the membrane filtration system provides a physical barrier that removes solids and bacteria, reducing the need for chemical treatment.

4. Enhanced Solids Retention: The membrane filtration system captures and retains solids, including bacteria and other microorganisms, within the reactor. This reduces the loss of biomass through effluent discharge and improves the overall performance of the biological reactor. By retaining the biomass within the reactor, the membrane filtration system reduces the amount of biomass lost from the system, resulting in a more stable and efficient process.

5. Reduced Sludge Production: Membrane filtration systems produce less sludge than traditional clarifiers, which reduces disposal costs and environmental impacts. By retaining solids within the reactor, the membrane filtration system reduces the amount of sludge produced by the treatment process. This results in significant cost savings and environmental benefits, as the amount of sludge that needs to be disposed of is reduced. 

For more than three decades, MEMCOR® membranes have been industry leading.  Since 1995, we have dedicated a team strictly to Membrane Bioreactor (MBR). Today, our technology operates in more than 200 municipal and industrial plants across the globe. Proven to deliver greater effluent and productivity, while reducing the lifecycle cost, MBR technology is preferred by the market. Our technology uses a fully automated process that provides liquid/solid separation by combining biological waste oxidation and membrane separation. In turn, this eliminates the need for any secondary clarification or tertiary filtration.

The MemPulse™ MBR technology helps delivers greater stability of the membrane environment, operational flexibility, and reduced maintenance requirements, which can result in significant cost savings. The system is successfully operating in applications ranging from municipal wastewater plants to the most difficult industrial applications such as oil refineries and landfill leachate. 

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