Saturday, September 21, 2019

Impending crisis spurs greywater recycling, rainwater harvesting

IT MAY sound like a cruel joke, but it’s true.

Many areas in the country, specifically Central Luzon, will run out of groundwater - one of the country’s most abundant resource - in eight to 10 years.

And yet, no one seems to be panicking, even after the Department of Environment and Natural Resources (DENR) and scientists from the University of the Philippines in Los Baños (Laguna) warned of a water crisis affecting provinces surrounding Metro Manila by 2025.

From the time warnings were issued on a possible water crisis and its dire ramifications on crop cultivation, commercial industries and domestic use, there has been no serious unified effort to avert a crisis.

But one government office in Central Luzon, is taking a bold leap to address the issue. Officials of the Bureau of Internal Revenue (BIR) will not just wait for the crisis to happen.

Just this March, the leaders of BIR in Central Luzon incorporated in their newly constructed four-building complex, two greywater treatment facilities – the first of its kind for a non-commercial and government establishment in Central Luzon.

According to BIR Regional Director Jethro Sabariaga, the low-impact and easy-to-manage treatment facilities recycle the complex’s greywater which could then be used for irrigation and indoor flushing.

And to top it all, the complex also features several rainwater harvesting systems to collect rainwater during rainy days for later use.

“It is our commitment to contribute and at least help in water conservation. We hope that this initiative will be an example for the private and government sectors to imitate,” Sabariaga said.

First ever greywater facility in CL

Greywater is the term applied to domestic wastewater that is drained from sinks, showers and kitchens.

Greywater is different from toilet wastewater (called "blackwater") which is generally flushed into septic tanks and, in some cases, flushed into drainage systems.

In a country like the Philippines, where there are no adequate and centralized sewerage systems, greywater is generally discharged, untreated, into the environment.

Sabariaga said that for BIR’s greywater treatment system, the wastewater drains into two facilities for the four buildings. The system was inspired from the system of the Laguna Lake Development Authority and was installed by an engineering company.

For the first step of the treatment process, the water passes through several long filtration canals of sand, gravel and rice husks.

DPJ Engineers and Consultants principal engineer Daniel Peckley Jr. said the filtration lines also feature plants growing inside the canals to aid in the filtration process.

These filtration lines remove dirt, food, grease, hair and inorganic compounds from the greywater.

The process mimics the biological purification processes which have minimal impact on the environment compared to commercially engineered water purification treatment systems.

From the filtration lines, the water runs through the aeration process in which water comes in close contact with air. This process also oxidizes organic chemicals that maybe in the water.

Peckly added that water is then stored in eight koi ponds all strategically located in and around the complex. Each pond can hold up to 450 cubic meters of treated greywater.

Water lettuce (Pistia stratiotes) is also raised inside the ponds to prevent over proliferation of algae and to provide cover for the fish population. Aside from their aesthetic proposes, the ponds serve as reservoir for the treated water for use in irrigation of the plants around the complex.

Peckly said that collected water is also stored for emergency use in case of building fire during the summer months. When the ponds reach their holding capacity, the water can be disposed into the public drainage system as the greywater has already been properly prepped for disposal into the environment.

Rainwater harvesting

The BIR complex is the first government facility in Central Luzon to employ an underground rainwater harvesting system.

Rainwater is trapped inside four cisterns than can hold 8, 000 liters of water each. The collected rainwater is then pumped into the four building’s plumbing system for flushing toilets. Peckly said that the BIR here will be able to save some 2,000 to 5,000 cubic meters of water.

“The objective of the design is to ensure that all buildings have sufficient supply of water while we minimize the need to source water from the local water utility. Sufficient water will always be available for fire protection,” Peckly said.

Implications on crop cultivation

Studies have showed that, aside from domestic water consumption, agriculture sector is the largest water user, consuming about 70 percent of the total global supply. This is where rainwater harvesting and as well as greywater could prove to be beneficial for use in crop cultivation.

Sabariaga said that the use of greywater for irrigation can spur renewed interest in community gardening. He added that households can use greywater to raise backyard crops and on a larger scale, communities can use greywater to irrigate farms.

The US Agency for International Development (USAID), which also predicted the water shortage by 2025, advocates “greywater use for household cleaning and irrigation and the use of treated wastewater for agriculture.”

The Philippine Rice Research Institute (PhilRice) also encourages farmers to make use of ponds to store excess water and even harvest rainwater for use in irrigation in times of long dry spells. The agency believes that small water impounding projects (SWIPs) addresses the unbalanced rainfall distributionduring the summer months.

Sabariaga said that other commercial and government buildings should consider putting up their own water harvesting systems to collect rain water for garden or community farm irrigation as well as for other economic uses.

SWIPS are more common in farm communities in Central Luzon, though their wider use have been practically slow and have yet to be implemented comprehensively in the region. Nonetheless, SWIPS have been proven to be effective for crop production.

Surprisingly, SWIPS are not new agricultural engineering interventions. In fact the Bureau of Soils and Water Management (BSWM) of the Department of Agriculture have started such projects as early as the 1950s.

The best known are the eight SWIPs in Talugtog, Nueva Ecija which have been placed under different agricultural studies. According to a study by Samuel M.Contreras, et. al, published in the International Soil and Water Conservation Research, SWIPs serve as rainwater harvesting facilities and storage structures consist of an earth embankment, spillway, outlet works and canal facilities.

“They are usually located in intermittent creeks or watercourses with potential uses for irrigation, fishery, livestock watering, and domestic uses,” the study added.

In Santa Rita town in Pampanga, farmer Pedro Mangiliman harvests rainwater in a 500 square meter pond. The pond also collects the water discharged from a nearby community pool. The water is saved to irrigate his small rice field during the summer months. The pond is also used to raise ducks and fish.

Harvesting rainwater, according to Mangiliman, reduces his cost for pumping out of groundwater and saves groundwater from extraction.

Helping the environment

The Philippine Clean Water Act of 2004 (Republic Act No. 9275) explicitly prohibits the discharge of wastewater into the environment. Waste water is the leading cause of organic pollution (at 48%) in the country’s water bodies, according to the DENR.

Sabariaga said that the BIR is ahead of everyone in the region as it has already taken steps to clean and recycle greywater while there is yet to be an adequate treatment and sewerage facility in the region.

However, while the BIR in Central Luzon is doing its part, pollution of underground and surface water sources is still a reality in most parts of the country.

In fact, water pollution is a serious problem that the DENR said that 31 percent of all illnesses in the country are attributed to polluted waters.

The National Sewerage and Septage Management Program (NSSMP), in report published in this paper, said that roughly 55 people in the country die every day due to lack of clean potable water source and because lack of adequate sanitation facilities.

DENR data shows that Philippines has 421 river basins, 72 lakes and a couple of ground water reserves but despite of this, the country still has communities with no access to clean water sources.

Why the need to conserve water?

Decades of indiscriminate domestic, agricultural and industrial use of groundwater resources have led to a significant decline in the quality of ground water sources not just in Central Luzon.

The excessive use of groundwater has been attributed as the main cause of subsidence and saltwater intrusion. Groundwater is sourced from aquifers (water-filled sandy layers underground) which are recharged through rain water seepage.

As Central Luzon’s population continues to grow, demand for fresh water is expected to double in 20 years with the demand most likely more felt in the urban areas, especially cities.

Central Luzon has at least 12-million-cubic-meter potential water supply and the need for fresh water is at an all-time high due to domestic and industrial demands.

An average person uses 80-100 gallons of water per day. The Philippine Statistics Authority reported that current population of Central Luzon, as of 2015, is at 11.21 million.

This means that the whole region consumes some 3.3 million to 4.2 million-cubic-meters of water daily, mostly sourced from ground and surface water sources like dams and irrigation systems.

The burden on the water supply will be most felt as the population of the region is expected to increase by at least two to three percent in 10 years.

Sabariaga said that, while the BIR is doing its part to conserve and recycle water, a unified plan of action should be taken by sectors in the region to address the water issue. He added that technologies and interventions are available and could be readily employed.

“The only issue here is our willingness to address the region’s water issue,” Sabariaga added.
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