Converting Waste to Assets: R-1 Wastewater

 
Whether solid waste or liquid waste, the challenge is the same-- can we turn this liability into a sustainable asset?  Our County's Director of the Department of Environmental Management, William Kucharsky, focused on the current efforts to reuse wastewater, but also touched on the recent sewage spill in Hilo Bay and composting.
 
Addressing current news first-- the ongoing sewage spill in Hilo Bay-- Bill explained the cause as a blocked sewage line.  The usual cause of a spill is a leak; blockage is unusual.  In this case, workers pulled out shirts, gloves, and a chisel, with the suspected source as the prison.  The department sampled 11 stations throughout Hilo Bay.  As of Tuesday (April 4), results indicated all clear for the inner harbor area around Coconut Island.  The sunny days have contributed to accelerating the natural microbial cleanup, so it is anticipated to be completely clear by Friday (April 7).
 
The County's first wastewater reuse project is underway at the Kealakehe Wastewater Treatment Plant, the system that serves Kailua-Kona.  Kona is an area where drinking water is precious, so this reuse project will provide a needed nonpotable source for irrigation and potential gray water systems.  The enhanced treatment would also reduce the impact on groundwater quality.
 
The existing aerated lagoon system has a capacity of 5.3 mgd with current flows approximately at 1.7 mgd.  The endangered native waterbirds-- Hawaiian coot and stilt-- love the ponds.  The reuse project will supplement the aerated lagoons with constructed wetlands, soil aquifer treatment, and ultraviolet (UV) to treat and disinfect the effluent to R-1, which is the highest reuse water quality.  
 
The demand for reuse water is anticipated to be seasonal with higher demand during the low-rain periods.  Any excess reuse effluent would flow to the soil aquifer treatment component where the polished effluent slowly infiltrates through sand and is acted upon by microbes or adsorbed to the sand particles to remove additional nutrients (particularly phosphorous), metals, and organics before seeping into the ground to minimize any impacts to the groundwater quality.
 
Potential users of the 1.0 mgd of R-1 reuse water include the proposed Kona regional park, the Old Airport Park, the Kohanaiki golf course, and the proposed master-planned Liliuokalani Trust project.
 
A quick note on composting-- the County actively supports composting.  The mulching will continue but will be held in piles for at least 30 days to generate sufficient heat to kill invasives such as fire ants and coquis before releasing free to the public.  Composting takes the mulch and adds additional organic waste such as food waste in an environment carefully controlled for moisture and temperature to produce compost. The current contract for a compost facility was not in a suitable location with potential odor impacts to existing communities.  The County has negotiated with the existing contractor to examine alternative locations and methods for a compost facility at a more reasonable price. 
 
Subsurface constructed wetland system: