Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/1056083
14 In Site December 2018 Water.desalination+reuse GROUNDWATER REPLENISHMENT • Project is demonstrating IDE's new Eco-Reuse water reuse treatment process • The results will inform a scheme to replenish Santa Maria Valley groundwater basin • The Central Coast Blue scheme is expected to comprise two water reuse facilities • The goal is to recycle three million cubes a year of wastewater A project to demonstrate a new water reuse technology has been running at City of Pismo Beach, California, US, since March. The project led by IDE Technologies is demonstrating the company's new Eco-Reuse technology. (The other firms involved are engineers Carollo and chemicals supplier Water Science Technologies.) The project site is a wastewa- ter treatment plant serving City of Pismo Beach. It's located on California's central coast, about mid-way between San Francisco and Los Angeles. The area is increasingly water scarce - the demonstration could develop into a project to replenish Santa Maria Valley groundwater basin with recycled wastewater. That scheme is part of a wider multi- million dollar regeneration programme in Pismo Beach, which includes renovating Pismo Beach Pier. The water reuse piece of the regeneration was originally named the Regional Groundwa- ter Sustainability Project. It was rebadged Central Coast Blue in February, to reflect the catch- ment of likely future customers: Municipalities Arroyo Grande, Grover Beach, the South San Luis Obispo County Sanitation District, and Oceano Commu- nity Services District. The proposed scheme will comprise two new water reuse plants, one at the demonstration site and the other at a location yet to be decided. The goal is to increase municipal groundwater supplies by 60 per cent, and reduce treated wastewater dis- charged into the ocean by 77 per cent. This equates to recycling 782 million US gallons a year (3 million m3/y) of wastewater. IDE demos Eco-Reuse reclaim tech THREE-PART DEMONSTRATION • Demo system takes a feed after the secondary clarifier • Chloramine-free system • Alternative solution to control membrane biofouling and scaling • Reduces formation of toxic N-Nitrosodimethylamine (NDMA) • Increases the efficiency of the UV-AOP The project is running in three phases, each of 90 days. Phase one started in March and demonstrated IDE's Eco-Reuse technology. Phase two switched to a conventional full advanced treatment (FAT) process for water reuse to provide compara- tive data. And from September, the site has been running IDE's Pulse Flow RO technology. The wastewater treatment plant that's hosting the demo has a conventional system of clarifiers. The plant has an activated sludge process that uses biology to reduce levels of ammonia, nitrates, and nitrites. It uses ferric chloride in the collection system to glom small particles together, making them bigger. The larger particles then drop out of the system more easily. The facility has a National Pollutant Discharge Elimination System (NPDES) federal permit for discharge into the area's waterways. The demonstration system is tak- ing a feed ašer the secondary clarifier. Part one: Eco-Reuse Eco-Reuse is similar to an FAT process, but with a few dif- ferences. The big difference is that does not use chloramine. Chloramine is normally dosed to control biofouling and scal- ing on the membranes. Instead, Eco-Reuse uses a new cleaning process developed by IDE called Direct Osmotic High Saline (DOHS). The DOHS process injects a short pulse of highly concen- trated saline solution into the membrane system. This saline pulse has several results: it causes bacteria to dehydrate, thereby deactivating them; it creates a backwash effect STEP 1 Chloramine dosing* *note: Chloramine is used to control biofouling on the membranes. It can promote formation of toxic N-Nitrosodimethylamine NDMA STEP 1 Ultrafiltration (UF)/ micro- filtration (MF) - removes suspended solids CONVENTIONAL FULL ADVANCED TREATMENT PROCESS (FAT) ECO-REUSE STEP 2 Ultrafiltration (UF)/ micro- filtration (MF) - removes suspended solids STEP 2 Reverse osmosis - filters out salt and dissolved organic matter such as viruses, and pathogens DOHS Direct Osmotic High Saline (DOHS) is a cleaning process and an alternative to chloramine dosing. It dehydrates bacteria, backwashes the membranes, and raises crossflow velocity on the membrane surface CONSERVATION Conservation is a preventative maintenance process that flushes the membranes twice daily. Prevents build up of biofouling and scaling. Extends intervals between clean-in-place process on the reverse osmosis system. STEP 3 Reverse osmosis - filters out salt and dissolved organic matter such as viruses, and pathogens STEP 3 UV-AOP* *note: Energy usage on UV-AOP reduced by up to 30 per cent by not using chloramine. STEP 4 Ultraviolet advanced oxidation (UV-AOP) - polishing