Expansion Made Easy with Adsorption Clarifier® California WTP Retrofits Existing Concrete Basins

Expansion Made Easy With Adsorption Clarifier® California WTP Retrofits Existing Concrete Basins

CASE STUDY

Location: El Dorado Hills, California Recommended Solution Owner: El Dorado Hills Irrigation District The solution to EID’s capacity vs. space dilemma came by way of Problem innovative thinking on the part of our Holding water rights that date back engineering experts, who suggested to California’s Gold Rush days, the converting unused concrete basins El Dorado Hills Irrigation District at the plant into a concrete version ® (EID) currently serves approximately of Adsorption Clarifier units and 128,000 residents in California’s concrete media filters. El Dorado County. This historic organization owns and operates The Adsorption Clarifier is a high-rate several water and wastewater clarification system that can be used treatment plants in the county, as a stand-alone pretreatment clarifier including the El Dorado Hills Water to filters or within a packaged system Like the tank version pictured, the concrete Treatment Plant (WTP), which treats such as the Trident. With a standard version of WesTech’s Adsorption Clarifier surface water pumped from Folsom hydraulic loading rate of 10 gpm/ provides clarification and flocculation. 2 Lake. The plant has undergone many ft (24 m/h), the Adsorption Clarifier changes over the years to meet a is designed to replace pretreatment as opposed to a settleable floc. A steadily increasing population. For equipment such as solids contact units retention screen atop the unit prevents example, in 1993, the plant installed or flocculation and settling equipment. media loss. two Trident® package water treatment The advantage of this system is a plants, which replaced equipment smaller footprint, lower profile, and a The Adsorption Clarifier achieves originally installed in 1960. Pleased cost savings to the owner. significant solids removal – typically with the operation of the Trident 70-90 percent of inlet water turbidity. technology, the plant installed The Adsorption Clarifier uses buoyant It does not require mechanical sludge another two units in 1995. media in an upflow system design. removal. Solids collected within The water travels upward through the the buoyant media are removed via When demand increased further, media and the floc that is produced is flushing, which consists of air scouring the plant had no available space for captured within the void spaces of the to expand the buoyant media and additional Trident units. The need to media and adsorbed onto the media. allow void spaces to increase, double the plant’s capacity from 8 to This process, which is called “contact 16 MGD (30-60 Ml/d), coupled with flocculation,” replaces conventional the lack of space, posed a significant flocculation and clarification. The goal challenge for EID. is to produce a “microfloc” that is removed in the buoyant media, combined with a raw water wash to Results flush the collected solids out of the Using the existing basins and the media. The waste is collected in a Adsorption Clarifier process allowed wash trough and directed to waste. the plant to double its capacity The second stage of the plant’s system without making major modifications included converting another concrete to the facility or purchasing additional basin into gravity filters containing land for new equipment. According mixed media (also referred to as to EID’s data (see the chart), the new multimedia or tri-media). The hydraulic systems produce effluent turbidity at or below 0.03 NTU and greater loading rate of the filter section is than 3 log removal of 5-15 micron- 5 gpm/ft2 (12 m/h). In general, this process has demonstrated the ability sized particles. to achieve filter effluent turbidity of < The plant operators continue to 0.1 NTU in full-scale applications, with be very pleased with the performance many plants – including the El Dorado of the original Trident systems and Hills plant – achieving effluent turbidity the Adsorption Clarifiers. Bill in the range of 0.02 to 0.05 NTU. Peterson, the plant’s chief operator, prefers this technology over Combined, the two processes Adsorption Clarifiers use buoyant media have demonstrated the ability to in an upflow system design. conventional treatment. achieve 99.9 percent turbidity removal with 3 log removal of 5-15 micron- sized particles.

EID data show turbidity below 0.03 NTU and greater than 3 log removal of 5-15 micron-sized particles. Surface water is pumped to the plant from Folsom Lake.