Water Works Engineers
HOME : Projects

Pukalani Wastewater Treatment Plant,
Hawaii Water Service Company, Maui, HI

Water Works Engineers designed an upgrade to the Pukalani WWTP. The existing plant, which used an extended-aeration activated sludge process, was replaced by a new 0.2 mgd membrane bioreactor (MBR) plant. The upgrade to the MBR treatment process allows the Pukalani facility to produce an effluent with an improved water quality (R-1) over the previously produced R-2 effluent. The MBR facility was designed for an initial phase of 0.2 mgd, average day flow and is expandable to 0.8 mgd. The structures constructed under the initial phase were sized for 0.4 mgd and the expansion from 0.2 mgd will only require the addition of membrane units and minor equipment.

The new process units added included fine influent screens, an equalization basin, anoxic and aerobic zones configured for biological nutrient removal (BNR), membrane basins with Kubota RW-400 flat plate submerged membrane units, process air system using positive displacement blowers, an inline ultra-violet disinfection system, a non-potable water system and a waste-activated sludge (WAS) storage basin. Effluent is stored in the existing 2.0 MG pond and pumped to the adjacent golf course for reuse. The WAS produced is pumped from the new storage tank to an existing belt press unit to be dewatered and transported to a composting site.

Water Works Engineers was responsible for coordinating the procurement of the MBR system and associated equipment from Ovivo, producing contract documents and obtaining permits from the Hawaii Department of Health (HDOH) and Maui County. Water Works Engineers was also the Owner’s representative during the construction phase and provide construction oversight.

3-D Model of Treatment Facility