half were caused by \u201cfats and rags\u201d<\/a>.<\/p>\nThe water that arrives at the plant is a smelly brown liquid made up mostly of water from showers, washing machines and toilets. <\/p>\n
But the final output is a fairly odourless and clear fluid. <\/p>\n
![\"Wastewater]()
Wastewater treatment specialist Jason Ewart shows the new membranes that filter out materials from Rotorua’s wastewater. Photo \/ Mathew Nash<\/p>\n
\u201cThere is a little bit of colour in there, almost a slight yellow tinge,\u201d Ewart said. <\/p>\n
\u201cWhen you put it in a glass beaker, it looks like sauvignon blanc.\u201d<\/p>\n
The upgraded process is expected to significantly improve treatment levels, reducing nitrogen from about 5-6mg\/L and phosphorus from around 3-4mg\/L down to much lower levels \u2013 an overall reduction of about 94%. <\/p>\n
E. coli counts are expected to drop from roughly 5400 per 100ml to less than one per 100ml, driven by UV disinfection. <\/p>\n
The treated water, which the council calls recovered water, will still not be suitable for drinking despite its wine-like appearance.<\/p>\n
Ewart said the upgraded facility had been designed with backup systems throughout the treatment process.<\/p>\n
\u201cWe always have one spare item for redundancy.\u201d<\/p>\n
![\"Wastewater]()
Wastewater at an early treatment stage. Photo \/ Mathew Nash<\/p>\n
He said two standby diesel generators would automatically start if the mains power supply failed, allowing the plant to continue operating.<\/p>\n
The project also aims to make it easier for treated wastewater to be reused.<\/p>\n
\u201cWe really wanted to remove that barrier,\u201d council environmental manager Alison Lowe said, with the higher standard of treatment now making that a possibility. <\/p>\n
Lowe said the council could apply for consent to allow the treated water to be reused for non-drinking purposes.<\/p>\n
![\"The]()
The plant produces almost clear, yellow-tinted water at the end of the treatment process. Photo \/ Mathew Nash<\/p>\n
Lowe said the project addressed several objectives, including capacity for growth and to deal with storms.<\/p>\n
She said the upgrade would also improve phosphorus removal and add a disinfection stage.<\/p>\n
As part of the upgrade, existing clarifier tanks will be converted into storage to help manage peak flows during heavy rain before the wastewater is fed back through the treatment process.<\/p>\n
An older membrane plant, installed about 13 years ago to increase capacity, will be decommissioned once the new system is commissioned, with treatment consolidated into a single membrane facility.<\/p>\n
The treated water is currently stored before being irrigated into the Whakarewarewa Forest. However, that arrangement will not continue in the long term.<\/p>\n
![\"Recovered]()
Recovered water is irrigated into the Whakawerawera Forest \u2013 for now. Photo \/ Mathew Nash<\/p>\n
A long-term solution for Rotorua\u2019s recovered water is being investigated by the council and a specially formed working group.<\/p>\n
Much of this discussion has remained behind closed doors because of \u201ccommercial sensitivity\u201d but three options have been finalised. <\/p>\n
Recovered water will either be applied to land, to constructed wetlands, or treated through advanced processes such as activated carbon systems.<\/p>\n
Engagement was underway with landowners, with design work to follow any agreements. <\/p>\n
How the new filtration system works<\/p>\n
Step 1: Screening \u2013 Wastewater passes through coarse and fine screens, removing items such as wet wipes, sanitary products and grit.<\/p>\n
Step 2: Biological treatment \u2013 It enters biological reactors, where naturally occurring bacteria remove nitrogen. Phosphorus is also removed at this stage before the water moves on.<\/p>\n
Step 3: Membrane filtration \u2013 The water is pushed through hollow-fibre membrane filters, which act as a fine physical barrier, removing bacteria and other remaining contaminants.<\/p>\n
Step 4: UV disinfection \u2013 Finally, the water is treated with ultraviolet (UV) light, which inactivates any remaining bacteria before the treated water is discharged.<\/p>\n
Mathew Nash is a Local Democracy Reporting journalist based at the Rotorua Daily Post. He has previously written for SunLive, been a regular contributor to RNZ and was a football reporter in the UK for eight years.<\/p>\n
– LDR is local body journalism co-funded by RNZ and NZ On Air.<\/p>\n","protected":false},"excerpt":{"rendered":"\u201cOn a peak day, during storm events, that can now go up to 72,000 once the upgrade is…\n","protected":false},"author":2,"featured_media":511329,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[12509,18990,5345,1132,11688,111,43,139,69,13028,4885,1327,38715,28797,2766,14043,78597],"class_list":["post-511328","post","type-post","status-publish","format-standard","has-post-thumbnail","category-new-zealand","tag-capacity","tag-completion","tag-increase","tag-million","tag-nears","tag-new-zealand","tag-news","tag-newzealand","tag-nz","tag-peak","tag-plant","tag-rotorua","tag-rotoruas","tag-significantly","tag-treatment","tag-upgrade","tag-wastewater"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/511328","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=511328"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/511328\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/511329"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=511328"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=511328"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=511328"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}