Wastewater trickle tower spraying arrangement

#This invention relates to the treatment of wastewater using one or more trickle towers employing biomedia. This invention particularly relates to the distribution of the wastewater over the biomedia.

#With greater demands being placed on the treatment of wastewater by regulatory authorities, there has become a growing need for systems that will treat wastewater to a higher level of purity. This has also brought an increasing need for systems that are more versatile in design and can more readily be adapted to handle differing wastewater treatment requirements.

#I have found that a trickle tower system employing strands of looped cord biomedia is more suited to handling today's increasing demands in wastewater treatment than the conventional systems currently in use. The initial approach of a looped cord biomedia trickle tower system is disclosed in my U.S. Pat. No. 6,241,889 published Jun. 5, 2001. While this tower system has been promising, and the general approach employed appears correct, further improvements and modifications are now desirable for more widespread adoption by industry and civil authorities.

#In the accompanying drawings, in which like reference characters in the same or different Figures indicate like parts:

#FIG. 1 is a schematic vertical section of a trickle tower wastewater treatment apparatus embodying the present invention;

#FIG. 2 is an elevational side view, with parts removed for clarity, of a single cell unit of the apparatus of FIG. 1;

#FIG. 1 shows an exterior, weatherproof, steel building 2 having a support structure 4 erected on a concrete base 6, with a covered recirculation tank 8 outside the building. Two wastewater treatment cells 10 are shown. Each cell 10 has an upper closure hood 12, with a flexible curtain 14 draped around the hood 12 and extending downwardly into a base receptacle 16 formed on the concrete base 6. Biomedia 18 is enclosed by the curtain 14, and a wastewater spraying or discharge system 20 is mounted inside the hood 12 above the biomedia, both as shown through broken away portions of the left cell 10. Various embodiments of the system 20 will be described in greater detail later, particularly with reference to FIGS. 21 to 29. Wastewater 22 from the system 20 flows down the biomedia 18 and drips into the base receptacle 16, illustrated as a base tray from which the partially treated wastewater flows to the recirculation tank 8 for recirculation to the system 20 of the same or another cell. Of course the base receptacle 16 could be constructed as a recirculation tank, so eliminating the outside recirculation tank 8. The hoods 12 are suspended by structural members 24, 26 supported by and forming part of the building structure 4, for example the roof rafters. The curtains 14 are attached and sealed to the outside of the hoods 12, and to the inside of the base receptacles 16.

#FIG. 2 shows one of the cells 10 in side view, the curtain 14 surrounding and defining this cell, extending downwards from the outside of the hood 12 to the inside of the base receptacle 16. Although various types of biomedia could be used inside the confines of the curtain 14, looped cord biomedia is preferred, and preferably the looped cord biomedia is tensioned vertically. To show such a arrangement, the side of the base receptacle 16 has been omitted to expose lower ends of four grates 28 (described in detail later) attached by adjustable tensioning bolts 29 to an anchor bar 30 extending horizontally across the base receptacle 16. These tensioning bolts 29 are a slip fit through holes in the anchor bar 30, to allow the bolts 29 to slip downwardly through the anchor bar 30, should any grate 28 lengthen and drop down a little in use due to the weight of the biomass forming on the biomedia strands of the grate. This prevents such strands from sagging in use, and further mitigates the possibility of biomass adversely bridging between adjacent biomedia strands.

#FIG. 3 illustrates in perspective view one of the curtains 14. It forms a tube-like casing, preferably made of flexible plastic sheeting, for example polyvinylchloride, polypropylene, etc. Due to the flexibility and deformability of the sheeting, the tube-like casing can have any required cross-sectional shape. As shown, it has a square cross-section 32; however, the cross-section may be rectangular, elliptical, circular, etc. In this way, the curtain 14 can be adapted to closely surround and define any shaped block of biomedia, whether solid biomedia, suspended strips, or looped cord. Around the top of the curtain is a series of small holes 34 reinforced by metal (preferably stainless steel) grommets 36. These holes are hooked over pegs extending from the hood (shown in FIGS. 4 and 5); this serves as an aid when mounting the curtain 14 around the hood 12, and it also provides physical support for the curtain 14 once mounted. Extending the full vertical length of the curtain 14 is at least one releasable fastener 38 closing an opening or slit in the curtain. There may be two, three, four or more such releasable fasteners 38, two being shown. These fasteners may comprise a standard type releasable zipper, preferably of plastic material, as used with outer coats such as Parkas, or may comprise any other type of releasable connection suitable around wastewater. Preferably, this fastener comprises inter-engaging looped and hook strips as sold under the trademark VELCRO, with attention being paid to the material and adhesive of the inter-engaging strips to resist reaction with the particular wastewater being treated. One function of the releasable fastener(s) is to facilitate assembly and mounting of the curtain 14 around the biomedia; this enables the biomedia to be assembled in place and then the curtain hung around the biomedia. Another function is to provide ready access to the biomedia, particularly for inspecting the condition of the biomedia in use, and for repairing or replacing the biomedia. Although the releasable fastener 38 preferably runs the full length of the curtain, one or more of these fasteners may extend only for a portion of the length of the curtain 14.