SE533702C2 - Treatment of sewage - Google Patents

Description

533 702 2 / thickener. In sloping terrain, self-drainage from the thickener can be used. Of course, regardless of the terrain, pumps can be used. The dimensions of the thickener are varied as needed.

A thickener with, for example, a diameter of 500 mm and a height of 800 mm has a capacity to thicken about 300 liters per hour. A normal household consumes a maximum of 200 liters of water per day.

To facilitate emptying, ie to reduce weight via thickening and self-drying, it is of course advantageous to use two dry thickeners alternately. This allows longer time for drainage and self-drying. In addition, at temperatures above the zero line, a decay can be obtained which further reduces the weight of the solid part. Such decontamination (anaerobic) usually leads to the formation of methane (biogas), which has a high energy value. Production of methane via anaerobic digestion is of particular interest in large plants which serve the drains of at least ten toilet seats. Better economic return is obtained if the thickened material is incinerated or used in a gasification plant. In large plants which serve at least five households, continuously operating thickeners are preferably used in the form of, for example, empty filters which can be supplemented with screw or piston presses.

The thickened material can of course also be used as a fertilizer, which is advantageously mixed with recovered ammonium nitrate (the preparation of which is described later). The natural manure thus extracted must of course be used on surfaces that are at a safe distance from watercourses.

The product should also not be used for growing vegetables.

To get an even till öd.e to the thickener, some type of buffer (not shown in fig.) Can be placed between the toilet seat and the thickener. Such a buffer may consist of a vessel or tube which is curved to form a screw-like (screw) configuration. In order to prevent odor and at the same time be able to effectively drain liquid from the container (prevent negative pressure), the upper part of the thickener is provided with a permeable gas filter 6. Such a gas filter can be made of peat fibers and lignocellulosic mixtures in mixture with suitable binder such as lignosulfonate, cellulose derivatives. hydroxyethoxy ethyl cellulose) and residues. Preferably, the residual lignin is used after acid hydrolysis of wood, sludge and / or bioslain. The gas filter should have a porous structure, but at the same time be resistant to moisture. and have an exposed and active surface area of> 10m2 / g.

A variant of the gas filter is to use activated carbon. Another variant is to fill the filter with granules which have different properties (such as size and density).

Another variant is the addition of ground wood material such as sawdust, wood chips and twigs. Furthermore, lignin obtained as a residual product in the production of ethanol and sulphate pulp from wood may be included. The main thing is that the material of the gas filter allows lasting and good air genome flow. 533 702 From the thickener, liquid is conveyed via the line 5 to a carburettor 7 on the bottom of which granules 8 of lime and / or ash lie. Preferably, ash is obtained, which is obtained after combustion of biofuels. Within the framework of the invention, a container can be placed between the thickener and the carburettor, which acts like a buffer and allows a further treatment of the liquid.

Depending on the reactions between the liquid and the alkaline granules in the carburettor, ammonia is released, which is brought into contact with a metal salt 9, such as magnesium chloride (MgCl 2) and / or magnesium sulphate (MgSO 4). Other suitable cations are salts of aluminum and zinc. Furthermore, light metals and preferably aluminum can be used to advantage, which emit hydrogen gas with ammonia. For efficient reaction, the aluminum is added in particulate form. Before the gas is reacted with the salt, the water vapor that may be present with the ammonia is removed. This is most easily done by condensing the gas mixture in a cooler 10, the water vapor being transferred from the vapor phase to the liquid phase while the ammonia gas is passed on for reaction with the metal salt.

A chemical reaction between the ammonia and the metal salt gives a metal amine, such as Mg (N H3) 6Cl2 (or Mg (NH3) 6SO4). One variant is to capture ammonia with a dilute acid in a "fermentation tube" ll. Preferably, nitric acid is used which, with ammonia, forms ammonium nitrate in the "fermentation tube". The carburettor can be supplemented with a vessel 12, which prolongs the time for the ammonia to escape. Released ammonia is passed via line 13 to the cooler (10) to be passed on to the metal salt (or acid).

Practically nitrogen-free liquid is passed from the carburettor (alternatively from the vessel 12) to a combi filter 14, the first stage of which may comprise sand and a second stage of peat and / or bark. Mixtures of bark and peat can also be used. A characteristic part of the invention is to return the water purified through the filter to the toilet seat by means of the line 15. It may be appropriate, before such recirculation, to purify the water in a fairly simple filter 16 available on the market. A UV "alter" may suffice. After such purification, the water can also be used for bathing and showering. Within the scope of the invention, the water from the combi filter can be carried directly out to ground 17 for infiltration. In accordance with the invention, dishwashing and shower water can also be treated. A perforated plastic bag placed in a barrel with a sealing ring was used as a separator.

A gas filter consisting of granules (diameter 1-2 mm) made of peat, pulp fibers (abrasive pulp) and residual lignin obtained from the production of ethanol from wood was mounted on the lid. 533 702 Year Separated liquid was taken to a carburettor filled with limestone whose dimensions varied from 2 mm up to 10 mm. Upon contact between the liquid and the limestone, the formation of ammonia was obtained. This ammonia was captured by a salt layer of magnesium chloride.

The basically nitrogen-free liquid was taken to a biolter consisting of peat and bark. Partially purified water was collected in a container with a volume of 100 liters. If necessary, water was pumped from the container to the cottage's toilet seat.

Described relatively simple experiments were performed during a summer month using a first dry thickener. The plant continued to be used for the rest of the summer by investing in a second thickener. Throughout the period, no disturbances occurred with respect to odor or liquid fl fate.

During the test, the toilet seat was used about five times a day. While the experiment lasted for 30 days and the volume of rinsing water amounted to 12 liters at a time, the total volume of the first thickener was about 1800 liters, while the volume in the separator at the interruption of the experiment was only 17 liters. When the test was interrupted, samples were taken to measure the dry content. The dry matter was found to be 14%. In other words, the solids content was only 2.4 kg (17x0.14). Even after 24 hours, the dry matter content was as high as 32%. Thus a very surprising result. After two weeks, the dry matter content was as high as Sl% and the total weight (substance + water) was only 4.6 kg.

As for the uptake of ammonia in the magnesium salt, this worked well and upon heating, hydrogen gas could be released which was ignited with cigarette lighters. Due to a lack of laboratory equipment, it was not possible to quantify the volume of hydrogen.

Advantages When applying the invention, your advantages are obtained. Thus, the emission of, among other things, the greenhouse gas ammonia is reduced by reaction with salts or an acid. Mixtures obtained containing ammonia can generate hydrogen or be used as a fertilizer (eg ammonium nitrate). which can replace part of the commercial fertilizer. which consumes energy during production. Therefore, the concept in accordance with the invention contributes to also indirectly reducing the emission of another greenhouse gas, namely carbon dioxide. The ammonium nitrate can be mixed with the thickened residue obtained in the thickener. Thus, a nutritious and "organic" fertilizer is obtained. In large plants, the contents of the thickener can be used for digestion and formation of methane. Other alternatives are gasification, which provides a high energy yield.

The contents of the thickener can also be burned. .

Running results in reduced water consumption. Not least, the system can be used in areas where water shortages are a major problem.

Claims (1)

A claim relating to the treatment of sewage (1) from, inter alia, animal stables and water closets (2), characterized in that the liquid-containing flow in a first stage is thickened in one or more separators (3), after which separated liquid is passed to a carburettor (7). ) wherein the liquid is brought into contact with alkaline substances (8), whereby ammonia formed in the carburettor is diverted for reaction with one of the substances magnesium chloride (9) or aluminum. Process according to Claim 1, characterized in that the alkaline substances in the gasifier (7) consist of lime and / or ash (8) in particulate form. Process according to one or more of Claims 1 to 5, characterized in that the ammonia formed in the carburettor is separated from water vapor by condensation in a condenser (10). Process according to one or more of Claims 1 to 3, characterized in that the liquid in the carburetor gases into a biolter (14) containing sand and peat. Method according to Claim 4, characterized in that purified liquid (15) is passed to a water closet (2).