CN214192928U - Small-flow sewage treatment system - Google Patents

Abstract

The utility model discloses a low discharge sewage treatment system, the system uses the circulation filler filter to carry out initial treatment to the sewage that comes from equipment such as septic tanks. The system provides the sewage intermittently to a circulating filler filter, allowing air to enter the filter, maintaining the high oxygen levels required for bacterial action. The circulating filler filter is connected with the subsurface flow constructed wetland. The sewage entering the system is divided into two parts, wherein 5-25% of the sewage bypasses a circulating filler filter and directly enters the subsurface flow constructed wetland, so that the bacterial action is promoted, and nitrate is converted into gaseous nitrogen.

Description

Small-flow sewage treatment system

Technical Field

The utility model relates to a sewage treatment field, concretely relates to low discharge sewage treatment system.

Background

Currently, in addition to sewage treatment systems that serve only a single dwelling, sewage treatment systems that rely only on septic tanks are difficult to meet the required environmental standards. In fact, even a single-dwelling septic tank may be out of specification if soil conditions or background nitrate-nitrogen content are not appropriate for the most commonly used sewage "treatment" systems, i.e., simply spreading the sewage over a large area below the surface of the earth.

Systems for treating septic tanks and other small flows of sewage, commonly referred to as "tertiary" treatment systems, require treatment beyond reducing organic strength, thereby reducing the biological nutrients in the sewage. Nitrogen is one of the most important biological nutrients and a particular problem in rural areas. However, rural areas have a low population density and municipal sewage treatment facilities are too expensive to build and maintain. Therefore, there is a need for a simple sewage treatment system for treating small amounts of sewage in rural areas.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a low discharge sewage treatment system to solve the problem that proposes among the above-mentioned background art.

In order to achieve the above object, the utility model provides a following technical scheme:

the system comprises a bypass device, a first flow path and a second flow path, wherein the bypass device is used for separating and conveying the sewage entering the equipment to the first flow path and the second flow path; the circulating filler filter with the filter medium comprises a water inlet connecting pipe positioned above the filter medium and a return pipe positioned below the filter medium; a recirculation tank having a first inlet connected to the return pipe of the circulating filler filter and a second inlet connected to the first flow path of the bypass device and receiving the sewage from the return pipe and the first flow path; a pump connected to the inlet port of the circulating filler filter and the recirculation tank and intermittently delivering the sewage from the recirculation tank to the inlet port of the circulating filler filter; the subsurface flow constructed wetland comprises a filter medium, the water inlet of the subsurface flow constructed wetland is connected with the water outlet of the recirculation tank and the second flow path of the bypass device, and the subsurface flow constructed wetland also comprises a water outlet for discharging sewage in the sewage treatment equipment.

Preferably, the filter media in the circulating filler filter has two layers, a lower layer being a coarse gravel layer and an upper layer being a fine gravel layer.

Preferably, the filter medium of the subsurface flow constructed wetland is a layer of medium gravel.

Preferably, the bypass device diverts 5% to 25% of the gas flow to the second flow path.

Preferably, the system further comprises a primary filter for separating solid matter from the waste water entering the apparatus before the waste water flows into the bypass apparatus.

Preferably, the circulating filler filter is a recirculating filler media filter.

The utility model provides a small flow sewage treatment system can utilize and promote the natural bacteria effect, consequently removes the whole process of nitrogen from sewage and only needs minimum control, need not trained personnel and operates to need not complicated and expensive equipment and can move.

The utility model discloses only with two essential elements, circulation filler filter and undercurrent constructed wetland, just realized the purpose of denitrogenation. This simple and relatively passive device requires little operator attendance and saves at least 50% energy compared to conventional suspended growth systems.

Drawings

Fig. 1 is a schematic view of the present invention.

Reference numerals: a sewage treatment system (10); a primary filter (12); a circulating filler filter (14); a metering tube (15); an undercurrent artificial wetland (16); a recirculation tank (18); a top layer (20); a lower layer (21); a liner (22); a drain pipe (23); a water outlet pipe (24); a gravel layer (26); a water inlet distribution pipe (28); a pump (30); a return pipe (32); a bypass device (34); a primary treatment device (36); a bypass pipe (38).

Detailed Description

The present invention will be further explained with reference to the accompanying drawings.

The drawings illustrate a preferred embodiment of the wastewater treatment system 10 of the present invention in which the primary filter 12, the circulating filler filter 14 and the subsurface flow constructed wetland 16 are important components. The recirculation tank 18 is an integral part of the recirculation charge filter 14.

The primary filter 12 may be a simple conventional screening device that functions to separate solid particles from the wastewater entering the treatment system 10, thereby preventing clogging of the circulating filler filter 14, bypass devices, and various piping and metering orifices in the treatment system.

The circulating filler filter 14 contains an impermeable liner to prevent contamination of the groundwater; the filter is filled with fine gravel or coarse sand filter media. The particles in the circulating filler filter 14 are distributed in the top layer 20, supported by the lower layer 21 of coarse gravel. A drain 23 is located in the lower layer 21 to supply water to a return pipe 32. The top layer 20 comprises a bacterial "fixed film" attached to the particles. The fixed film is a variety of bacteria already present in the treated sewage, which adhere to the surface of the media particles to form the top layer 20.

The subsurface flow constructed wetland 16 is constructed with a water impermeable liner 22 covering the bottom and extending up to the sides to prevent contamination of the groundwater. A network of outlet pipes 24 is located directly above the bottom liner and a gravel layer 26 covers the outlet pipes 24 and the bottom liner 22. An inlet distribution pipe 28 is located above the gravel layer 26 to distribute incoming sewage across the top of the gravel layer 26.

The dosing pump 30 connects the recirculation tank 18 with the circulating charge filter 14 and is the only source of sewage supplied to the circulating charge filter 14 for treatment. The sewage enters the circulating filler filter 14 through the network of metering tubes 15, thereby distributing the sewage throughout the top layer 20. The return pipe 32 also connects the circulating charge filter 14 to the recirculation tank 18 and serves to return the sewage drained from the media to the tank.

The bypass device 34 receives sewage from a primary treatment unit 36 (typically a septic tank) through the prefilter 12 and directs a majority of the sewage into the recirculation tank 18 while allowing a portion of the sewage to flow directly into the subsurface constructed wetland 16.

The primary treatment facility 36 removes the solid waste by settling the solid waste to the bottom of the tank. However, a second device is also required to further remove the solids.

The secondary treatment device is a primary filter 12. The primary filter 12 removes residual solids from the wastewater and thereby prevents plugging of subsequent treatment equipment, particularly the spaces within the filter material in the circulating filler filter 14 and circulating media dosing side tube.

The recirculation filler filter 14 and the recirculation tank 18 operate together to perform a nitrification step, in particular to add oxygen to the sewage from the primary filter 12. In effect, the contaminated water enters the recirculating fill filter 14 through the recirculating tank 18.

To maintain the desired aerobic conditions in the circulating filler filter 14, the sewage from the recirculation tank 18 is intermittently supplied to the circulating filler filter 14 by pulses of the pump 30. When a large volume of contaminated water is produced, the contaminated water is circulated from the recirculating filler filter 14 back to the recirculation tank 18, thereby allowing air to enter the space within the filter media of the top layer 20. This provides sufficient oxygen to maintain aerobic conditions within layer 20.

The fixed film is attached to the medium of the circulating filler filter 14, and bacteria extract nutrients necessary for respiration and growth from the sewage when the sewage flows through the fixed film, thereby purifying the sewage. The sewage is fed to the circulating packed filter 14 by means of a pulsed feed, and aerobic conditions are maintained in the circulating packed filter 14.

The circulating filler filter 14 is followed by an underflow constructed wetland 16 into which sewage from the circulating filler filter 14 flows for denitrification. The flow of sewage from the circulating packed filter 14 into the subsurface flow constructed wetland 16 is controlled by a conventional float valve which diverts all or a fixed portion of the sewage into the subsurface flow constructed wetland 16 when the liquid level in the recirculation tank 18 reaches a specified level.

The subsurface flow constructed wetland 16 provides an anoxic environment necessary to convert nitrate-based nitrogen in the wastewater exiting the circulating packed filter 14 to nitrogen. When the sewage is exposed to the anoxic environment in the subsurface flow constructed wetland 16, the natural respiration of the bacteria in the sewage completes the process.

The bypass flow in bypass conduit 38 from bypass device 34 serves to assist the denitrification process. The bypass device 34 diverts some of the untreated sewage from the primary treatment device 36 around the circulating filler filter 14 and the untreated sewage flows directly into the subsurface constructed wetland 16. The bypass flow is 5% to 25% of the total sewage flow, the ratio depending on the intensity of the incoming sewage and the limit of nitrogen concentration in the system output. The raw sewage flowing into the subsurface flow constructed wetland 16 has a dual purpose, namely: provides a carbon source for the denitrification process and accelerates the transformation of aerobic conditions in the circulating filler filter 14 to anoxic conditions required for denitrification in the subsurface flow constructed wetland 16.

Claims (6)

1. A small flow sewage treatment system is characterized in that: the system comprises a bypass device, a first flow path and a second flow path, wherein the bypass device is used for separating and conveying the sewage entering the equipment to the first flow path and the second flow path; the circulating filler filter with the filter medium comprises a water inlet connecting pipe positioned above the filter medium and a return pipe positioned below the filter medium; a recirculation tank having a first inlet connected to the return pipe of the circulating filler filter and a second inlet connected to the first flow path of the bypass device and receiving the sewage from the return pipe and the first flow path; a pump connected to the inlet port of the circulating filler filter and the recirculation tank and intermittently delivering the sewage from the recirculation tank to the inlet port of the circulating filler filter; the subsurface flow constructed wetland comprises a filter medium, the water inlet of the subsurface flow constructed wetland is connected with the water outlet of the recirculation tank and the second flow path of the bypass device, and the subsurface flow constructed wetland also comprises a water outlet for discharging sewage in the sewage treatment equipment.

2. A low-flow sewage treatment system according to claim 1 wherein: the filter medium in the circulating filler filter has two layers, the lower layer is a coarse gravel layer, and the upper layer is a fine gravel layer.

3. A low-flow sewage treatment system according to claim 1 wherein: the filter medium of the subsurface flow constructed wetland is a layer of medium gravel.

4. A low-flow sewage treatment system according to claim 1 wherein: the bypass device divides 5-25% of the gas flow to the second flow path.

5. A low-flow sewage treatment system according to claim 1 wherein: the system also includes a prefilter for separating solid matter from the waste water entering the apparatus before the waste water flows into the bypass apparatus.

6. A low-flow sewage treatment system according to claim 1 wherein: the circulating packed filter is a recirculating packed media filter.

Images