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Technique hydrocyclone and re-injected into the CEHRC process for re- use. The lighter densi- ty sludge is discharged out of the top of the hydrocyclone. CEHRS + PAC Process Review The CEHRS process can easily be com- bined with a PAC recycle/contact step to produce a pro- cess "offspring" that Figure 2: A CEHRS/PAC (ACTIFLO® CARB) process schematic. (Image provided by Kruger Inc.) utilizes the high rate settling of the CEHRS process with the adsorption capabilities of PAC. A general overview of this CEHRS/PAC process (see Figure 2) is: a PAC contact tank resides directly ahead of the CEHRS process. This tank allows for contact time of raw water with fresh and recycled PAC. A target solids concentra- tion is maintained in this contact tank at a specific residence time. From here, the aforementioned CEHRS process steps occur; instead of the sludge/ PAC slurry being wasted imme- diately, it is recycled back to the PAC contact tank. The PAC tank enables the process to exploit the well documented adsorp- tion properties of PAC. Fresh PAC is added to the raw water stream as it flows into the con- tact tank with the recycled PAC/ Sludge. Contact tank solids are wasted at a rate that keeps the entire solids balance within the CEHRS system in equilibrium and makes the most use of the PAC adsorption sites. Pilot Program Review Testing was completed in two phases to capture seasonal variations of test sites. Phase 1 occurred in April 2011 and Phase 2 during July/August 2011. A number of operating parameters were varied and monitored throughout the study although the most relevant parameters for discussion would be the fresh PAC doses and the removals of some TOrCs at those doses. Wood-based PAC was used throughout the study after pre- wateronline.com ■ Water Online The Magazine, Wastewater Edition 29 pilot screening. The pre-screening demon- strated that the wood- based PAC provided for a good balance of performance and economic feasibility when compared to coconut-based PAC. Ten specific TOrCs were selected to be analyzed for removal efficiencies. These selected compounds in alpha order were: caffeine (stimulant/ tracer), carbamazepine (anti-epileptic), diltiazem (anti-hyper- tensive), diphenhydramine (antihistamine), fluoxetine (anti- depressant), naproxen (anti-inflammatory), ofloxacin (anti- biotic), sulfamethoxazole (antibiotic), triclosan (biocide), trimethoprim (antibiotic). Pilot Testing Results The summary of results can be seen in Table 1-2. This is Together, Meeting the Challenges of Clean Water Are you looking for ways to improve your wastewater sludge management, to boost more biogas from your anaerobic digesters or to EHWWHU FRQWURO VXOßGHV LQ \RXU process and collectors? Kemira can help you solve these challenges and much more. At Kemira, water is the connection to our customers. We are a global water chemistry company serving municipalities and water intensive industries. Kemira has the knowledge to work with our customers in developing innovations that address the sustainable future of water. Tel. 800 465 6171 usinfo.wateronline@kemira.com www.kemira.com kemira oyj kemiragroup