Ticking all the boxes - A cost effective installation, low running costs, high quality effluent and consent compliance! Achieved using a textile packed bed reactor

In 2009, the Auckland Regional Council received a number of odour complaints from a wastewater treatment and disposal system servicing a mixed use residential/commercial block in Kumeu, West Auckland. Andrew.Stewart Ltd were engaged by the client to provide engineering and planning services which included a ‘fit for purpose’ assessment of the existing treatment system, a new resource consent application and a new upgraded treatment plant and disposal system. The client wanted a solution that was cost effective due to the proposed reticulation of Kumeu Township, due to be completed in the next 2 years.

The residential/commercial block includes a cafe, a Chinese restaurant, offices, a small dairy/grocery store and a residential accommodation for 5 people. In 2001, a Bioflow 2000 system was installed to treat the wastewater to secondary standard prior to disposal via a PCDI disposal system. For a number of reasons the system was unable to treat the strong wastewater generated from the commercial block and partially treated wastewater was discharged to land resulting in regular odour complaints from neighbouring businesses.

Refurbishing/upgrading the existing treatment system was uneconomic due to the small tank sizes and lack of space for a grease trap and buffer tank. Andrew.Stewart Ltd presented the client with a number of options to produce secondary effluent quality prior to land application of treated wastewater.

Following a period of flow monitoring to determine the average and peak wastewater flows and influent sampling, a robust treatment process based on textile recirculating packed reactors was chosen. Two providers of this technology were asked to submit proposals based on a performance based specification; the installation and maintenance contract was subsequently awarded to Jet Water and Waste Systems Ltd. The Jet commercial packed bed reactor had been under development for a number of years and this was the first system installed within the Auckland Region.

The treatment plant was designed to treat peak flows of up to 1,600 litres per day and to produce advanced secondary treated effluent.

The paper covers wastewater treatment and disposal, engineering design, installation and plant performance.