IES20050441A2

IES20050441A2 - A waste treatment system

Info

Publication number: IES20050441A2
Authority: IE
Inventors: Francis Oliver Hannon
Original assignee: Francis Oliver Hannon
Priority date: 2005-06-30
Filing date: 2005-06-30
Publication date: 2006-10-04

Abstract

Waste material having a solids content of less than about 22% is treated by first directing waste having a solids content of less that 22% into an infeed tank. Waste from the infeed tank is delivered into a holding tank and then onto a conveyor. Waste on the conveyor is exposed to microwaves and heat is applied to the waste on the conveyor to evaporate moisture. Evaporated water is condensed and filtered. The dried waste is discharged from the heater into a trailer for onward transportation.

Description

Introduction The invention relates to a method an apparatus for treating sludge-type waste material having a solids content of from 6% to 25%.

Large quantities of sludge with low levels of solids present major treatment and disposal problems for a wide range of industries and public authorities. Various treatment systems are used, however in general these are either very costly or do not efficiently and effectively deal with the waste material.

This invention is directed towards providing an improved method and apparatus to effectively and efficiently treat such waste materials.

Statements of Invention According to the invention there is provided a method a solids content of less than about 22% comprising the steps of: directing waste having a solids content of less than 22% into an infeed tank; delivering the waste from the infeed tank into a holding tank; delivering the waste from the holding tank onto a conveyor; exposing the waste on the conveyor to microwaves; applying heat to the waste on the conveyor to evaporate moisture; INT ) OPEN TO PUBLIC INSPECTION UNDER SECTION 28 ANO RULE 23 JNL No. of «1.1' for treating waste material having ΙΕ ο 5 0 4 4 1 HANIOI/P -2condensing the evaporated water; filtering the condensed water; and discharging the dried waste from the heater into a container.

In one embodiment the waste has a solids content of less than 15% and the method comprises the steps of:delivering the waste into a separator; and separating the proportion of the moisture from the waste to increase the solids content of the waste prior to delivery into the infeed tank.

Typically the solids content of the waste from the separator is at least 18%.

In one embodiment waste is delivered to the separator from a tanker. The waste may be delivered directly from the tanker into the separator.

In another embodiment the waste has a solids content of at least 15% and the waste is delivered from a trailer directly into the infeed tank.

Dried waste may be discharged into a trailer.

In one case dried waste is discharged directly from the heater into a trailer.

The invention also provides dried waste when treated by a method as claimed in any preceding claim.

IE 0 50 4 4 1 HANIOI/P -3Brief Description of the Drawings The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, in which: Fig. 1 is a schematic flow diagram of a waste treatment system according to the invention; Fig. 2 is a side cross sectional view of an infeed tank used in the system of the invention; and Fig. 3 is a schematic view of a heating system used in the invention.

Detailed Description Referring to the drawings and initially to Fig. 1 there is illustrated a system 1 and method for treating waste material with a high moisture content. The solids content of the waste sludge is typically less than 22% and may be as low as 6%.

In the case of sludge with a solids content of typically 6% to 15% the sludge is delivered to the treatment facility by a tanker 2. In the case of waste with a solids content of typically 15% to 22% the waste is delivered to the treatment facility by a trailer 3. Dried waste material treated by the system and method of the invention is preferably discharged directly into an outfeed trailer 4 to be transported to a disposal or further treatment location. The system 1 ensures that the waste is quickly and efficiently handled and treated and is processed without a requirement for storage facilities at the treatment location.

In the case of sludge with a solids content of 6% to 15%, the sludge is delivered by a pump 10 directly from the tanker 2 into a pre-treatment separator 11 which may be in the IE 0 5 0 4 4 1 HAN101/P -4form of a decanter or centrifuge. The separator 11 processes the sludge to increase the solids content to above 15%, typically from 16% to 22%. The pre-treated waste is discharged from the separator 11 onto a conveyor 12 which delivers the waste into an infeed tank 15. Waste with a solids content of 16% to 22% delivered by the trailer 3 is directly discharged into the infeed tank 15. The infeed tank 15 will be described in more detail below. The tank 15 has a relatively large capacity of typically about 45 tons. The waste in the tank 15 is delivered on demand into an intermediate smaller capacity feed tank 16.

The waste is then processed by first treatment 17 in multiple stages with microwaves which kill substantially all pathogens and the waste is then dried in a direct heater 18 prior to discharge directly into the output trailer 4.

Referring to Fig. 2, the infeed tank 15 is generally retilinear in plan view and comprises a sloped base 40 and side walls which define a tap 41 at the upper edge thereof. The tap 41 has a sludge inlet 42 closable by a ram operated lid 43. Sludge is delivered into the infeed tank 15 in the direction of arrow A from a tipper truck 3. The tank 15 is below ground level so that the truck 3 can reverse up to the tap of the tank and, an opening of the lid 43, deliver sludge into the tank 15. The side wall 45 closest to the sludge inlet 43 is sloped to ensure free flow of sludge to the base of the tank 15. Six discharge screws 47 are Iocated at the bottom of the tank 15 to deliver the sludge to a discharge outlet from which the sludge is delivered by another screw to the intermediate feed tank 16 from which the sludge is delivered on demand to a treatment system.

In more detail, and referring especially to Fig. 3, waste from the feed tank 16 is delivered into a hopper 20 having a screw conveyor 21 at the outlet end thereof. The screw 21 delivers the waste onto and across a mesh conveyor 22. The waste on the conveyor 22 is led through multiple, in this case six, microwave treatments 25. A microwave treatment system is described in detail in US 6,618,957. The microwaves subject the waste material to high frequency radio waves in the ultra high frequency band. The pathogens ΙΕ ο 50 4 4 1 HAN101/P -5and polar water molecules in the waste material attempt to align themselves with the oscillating electric field at a frequency of 915 MHz. However, the pathogens or molecules within the pathogens cannot align themselves synchronously with a resultant atmosphere of excitement which causes the pathogens to explode structurally. Water molecules attached to the pathogens are released in the form of water vapour into a heated chamber.

After microwave treatment as described, the conveyor 22 delivers waste to a direct heating station 28 at which heat is directed to the waste to dry the waste. Water vapour generated during the process is delivered to a condenser 30 and the condensate is passed through a filter 31 to substantially remove any entrained material, prior to disposal of the filtered water.

The invention provides a waste treatment system and method which is highly efficient at killing pathogens and drying the waste. The system is capable of handling waste with a wide range of solids content and the resultant waste is substantially free from pathogens and is dried to typically an 80% solids content. Incoming untreated waste and outgoing treatment waste is quickly and efficiently received and discharged, respectively so that on-site storage is minimised.

The invention is not limited to the embodiments hereinbefore described which may be varied in detail.

Claims

1. A method for treating waste material having a solids content of less than about 22% comprising the steps of: directing waste having a solids content of less than 22% into an infeed tank; delivering the waste from the infeed tank into a holding tank; delivering the waste from the holding tank onto a conveyor; exposing the waste on the conveyor to microwaves; applying heat to the waste on the conveyor to evaporate moisture; condensing the evaporated water; filtering the condensed water; and discharging the dried waste from the heater into a container.

2. A method as claimed in claim 1 wherein the waste has a solids content of less than 15% and the method comprises the steps of:delivering the waste into a separator; and separating the proportion of the moisture from the waste to increase the solids content of the waste prior to delivery into the infeed tank. IE 0 5 0 4 4 1 HAN101/P -7A method as claimed in claim 2 wherein the solids content of the waste from the separator is at least 18%, waste may be delivered to the separator from a tanker, the waste may be delivered directly from the tanker into the separator. A method as claimed in claim 1 wherein the waste has a solids content of at least 15% and the waste is delivered from a trailer directly into the infeed tank, dried waste may be discharged into a trailer. Dried waste when treated by a method as claimed in any preceding claim.