US 5,236,595 A · Method and apparatus for filtration with plural ultraviolet treatment stages

Abstract

An improved filtration system involving the use of ultraviolet irradiation, ozonation, chlorination, reactive filtration media, chemical treatment, compressed air aeration, air emission control, and central flow control is described. The process system and apparatus of the present invention mainly include a liquid pump, an ultraviolet pretreatment means, a central flow control, an air emission control means, a reactive pressure filter, a process tank, at least one chemical feeder means, an ultraviolet post-treatment means, and an aeration means. The filter media are of reactive type, including diatomaceous earth, granular activated carbon, fibrous activated carbon, granular metal medium, greensand, neutralizing sand, silica sand, activated alumina, ion exchange resins, polymeric adsorbents, chemical treated adsorbents, manganese oxide, coal, porous plastic medium, porous stainless steel medium, porous ceramic medium, bacteriostatic filter medium, porous paper filter medium, porous carbon filter medium, coalescing filter medium, fiberglass filter medium, or combinations thereof. The process tank contains and handles regenerating chemicals, flocculating chemicals, filter aids, or recirculating water. The reactive filter media of this invention are regenerated by either chemical reactions or aeration for reuse to prolong the filter media's service life and to reduce the operation and maintenance costs. Said air emission control means is provided when compressed air aeration is applied to said pressure filter for regeneration of said reactive filter media. The apparatus of this invention is compact and simple, and can cost-effectively remove suspended, dissolved, volatile, radioactive and living contaminants from a contaminated liquid.

A filtration method for removing contaminants from a contaminated liquid comprising the following steps:

(a) operating an apparatus comprising an influent liquid pipe, effluent discharge pipes, a waste drain, process pipes, an ultraviolet pretreatment means, a chemical feed system, a pump means, a process tank, a pressure filter means including reactive and non-reactive filter media and at least one filter septum, an ultraviolet post-treatment means, and a central flow control means in a filtration mode,
(b) pumping the contaminated liquid to said influent liquid pipe of said apparatus,
(c) disinfecting the contaminated liquid by said ultraviolet pretreatment means, as needed, producing an ultraviolet pretreated liquid, and discharging said ultraviolet pretreated liquid to either said process tank or a process pipe connected to said ultraviolet pretreatment means,
(d) feeding a chemical, as needed, to the ultraviolet pretreated liquid in said process tank or a process pipe using said chemical feed system for chemical pretreatment and thereby producing an ultraviolet pretreated liquid, or a chemical pretreated liquid, or both,
(e) pumping the ultraviolet pretreated liquid, or the chemical pretreated liquid, or both to said central flow control means and pressure filter means which comprises said filter media and at least one filter septum,
(f) filtering the ultraviolet pretreated liquid, or the chemical pretreated liquid, or both by said filter media supported by said filter septum inside said pressure filter means for removal of suspended, dissolved, radioactive, living and non-living contaminants, and producing a filter effluent,
(g) periodically discharging a concentrate produced inside said pressure filter means though an on/off valve during a prolonged filtration operation, and periodically discharging a waste sludge produced inside said process tank,
(h) discharging the filter effluent from said pressure filter means through said central flow control means to said effluent discharge pipe where the filter effluent is treated by the ultraviolet post-treatment means, and producing a post-treated effluent or a product liquid,
(i) periodically turning said central flow control means manually or automatically from said filtration mode to a backwash mode, for backwashing said pressure filter means at a liquid flow direction opposite to that of the filtration mode using the ultraviolet pretreated liquid or the chemical pretreated liquid or both and thereby producing, then discharging a backwash wastewater from said pressure filter and said central flow control means to said waste drain for disposal,
(j) turning said central flow control means manually or automatically to a rinse mode, for rinsing said pressure filter means at a liquid flow direction identical to that of the filtration mode with said ultraviolet pretreated liquid or chemical pretreated liquid, or both and thereby producing, then discharging a rinse wastewater from said pressure filter means and said central flow control means to said waste drain for disposal,
(k) turning said central flow control means manually or automatically from said rinse mode to the filtration mode again for filtering, thereby producing another filter effluent and another concentrate, and repeating steps (a) through (h),
(l) turning said central flow control means manually or automatically to a bypass mode, allowing the ultraviolet pretreated liquid to bypass said pressure filter means and to be post-treated by said ultraviolet post-treatment means for producing a non-filtered but disinfected product liquid,
(m) periodically turning said central flow control means manually or automatically to a flushing mode, for flushing the influent liquid pipe and the ports of said central flow control means and thereby producing, then discharging a flushing wastewater to said waste drain for disposal,
(n) manually or automatically turning said central flow control means to a preparation mode, for preparing a chemical solution in said process tank, using said contaminated liquid and chemical from said chemical feed system,
(o) turning said central flow control means manually or automatically to a recirculation mode, for recycling said chemical solution throughout the entire apparatus comprising said pump means, said chemical feed system, said central flow control means, said pressure filter means, said process tank, and said piping system to regenerate said filter media without discharging said product liquid and said wastewater,
(p) turning said central flow control means manually or automatically to a precoat mode, for precoating said filter septum with said reactive granular filter media inside said pressure filter means by recirculation of the effluent of said process tank and said filter media from said chemical feed system,
(q) turning said central flow control means manually or automatically to a desorption mode, for removing a residual water, regenerating said reactive filter media inside said pressure filter means and thereby producing an emitted gas effluent all using a gas compressor means, and for purifying said emitted gas effluent using an air emission control means comprising a tank, at least one prescreen, a gas mover, a venturi dilution means, a demister, an adsorber, valves, and pipes, and
(r) turning said central flow control means manually or automatically from either said precoat mode or said desorption mode to the rinse mode for rinsing and then to the filtration mode for filtering and thereby continuously producing the product liquid.

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Method and apparatus for filtration with plural ultraviolet treatment stages

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Method and apparatus for filtration with plural ultraviolet treatment stages

Life of this patent

Abstract

Claims19