Heavy Metal Pollution, Marilao

Marilao, Philippines
Southeast Asia,
Tannery Waste, Solid Waste, Sewage, Pesticides, Hexavalent Chromium, Heavy Metals
Potentially affected people:


Project Completion Report (PDF)

Heavy metal pollution of the Marilao-Meycauayan-Obando River system (MMORS), located in the province of Bulacan, Philippines, has caused environmental degradation and numerous public health problems.  The contamination of this waterway comes from both formal and informal industries, such as used lead acid battery recycling, gold and precious metals refining, jewelry making, and open dumpsites. Many of these toxic metal pollutants far exceed national standards and therefore create a significant human health problem.

The river systems from these municipalities are “hot spots” of water quality. The emissions and wastes from the industrial processes find their way into the atmosphere, river system and eventually to fishponds before finally exiting the Manila Bay.  The fishponds form the basis of a thriving aquaculture industry that provides both an important source of income for coastal families and food for hundreds of tho usands of people in Metro Manila.  The likelihood of disease due to heavy metal poisoning decreases life spans and becomes a serious and widespread threat to public health and environmental well-being.


These conditions in the MMO have spurred Blacksmith Institute to address these environmental-social concerns. Since 2005, Blacksmith Institute has been organizing and mobilizing the stakeholder’s group in the area to address the pollution problems in the river system. It has supported river quality monitoring of the Department of Environment and Natural Resources-Environmental Management Bureau (DENR-EMB) Region 3 and NCR to help identify the MMO River System as a non-attainment area (NAA). This is a requirement to proclaim the MMORS as a Water Quality Management Area.

In 2008, it received funding to undertake pilot projects for the mitigation and remediation of industrial pollution, particularly that of heavy metals, and for the mobilization of the community and local stakeholders to clean up the river system.


Water Quality:

The water quality of the MMORS was tested for heavy metal contamination in March and October of 2008. High levels of toxic heavy metals such as copper, manganese, lead, and zinc were found in all three rivers. These metals were also found in tilapia, prawns, and other fish in concentrations that far exceed national health standards.



Worker Health:

The industries that line the rivers were   also surveyed to assess how they could  improve their occupational health and limit their contamination by toxic substances. Both tannery workers and gold smelters are exposed to hazardous chemicals, so Personal Protective Equipment, safety education, and regular monitoring were all recommendations proposed by the study.

Community Health and Perceptions:

Many residents living near tanneries and refiners attributed health problems such as asthma, tuberculosis, heart disease, and skin problems and to these industries. They also recognized that employers like Philippine Recyclers Incorporated play a significant role in the local economy.They would like industry to take measures to decrease their pollution.




Different technologies are being explored for the remediation of toxic metals created by the industries.  A chrome recovery facility is now in its second year, and a wastewater treatment plant that uses aerobic bioremediation for tannery waste is completely finished and being used as a model for other tanneries.
A pilot test of a scrubber that controls air pollution from gold and precious metals refining is currently being assessed for effectiveness.



Government Participation:

The MMORS was formally declared as a Water Quality Management Area (WQMA) by the Department of Environment and Natural Resources on May 14, 2008, seven months ahead of schedule.
Educational workshops have also been held with tannery operators and gold refiners, in which best practices to minimize pollution were identified.



Contaminated Soil Mapping and Soil Removal

Soil samples from schools, parks, markets, and other public places in the project area in order were tested in order to identify hot spots of heavily contaminated soil that require immediate treatment. The local government has agreed to place contaminated soil in drums for storage in local facilities, but work is still ongoing to find enough safe locations.



Significant improvements in the river quality may take months and even years.  Through successful pilot demonstration activity, the building blocks required for a comprehensive and integrated river system rehabilitation have been already laid.  However, our long-term strategy is currently still pending final approval.



Community action which is required in order to sustain efforts to rehabilitate the river system could only be ensured if community members recognize the broader spectrum of effects linked to heavy metal pollution of the MMORS. The baseline studies, although requiring additional time/resource investments by  stakeholders and funding institutions, also helped develop interventions that are technologically, socially and politically feasible.

The pilot demonstration project have paved the way for the proposed larger scale clean-up of the river system and have set the tone to achieve our vision of making MMORS a healthy river to ensure the health of the people.


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