DD217787A1 - PROCESS FOR OBTAINING BIOGAS FROM GUELLE - Google Patents

Abstract

The invention relates to an intensive process for obtaining energy in the form of biogas by culturing bacteria on bark. According to the well-known method of anaerobic fermentation of guelle, the organic substance contained in the bark is biologically converted into methane and carbon dioxide in the mesophilic region only at a low rate of degradation. An increase in the space-time yield is possible by the transition to the thermophilic range or by a kinetic control of the activity of the methane bacteria. For the latter method, a separation of the biogas reactors into an acetogenic and methanogenic digester space or the operation of two reactors for the different stages is necessary. The aim of the invention is to utilize the total reactor volume available for methane production. The aim is achieved by subjecting the guella in the stable area to an acetogenic fermentation and only after completion of the fermentation from the extraction pit the biogas reactor is fed to the bacterial methane formation, taking advantage of the different culture conditions of methanogenic and acetogenic microorganism populations. During this fermentation in the stable area there is no loss of usable ingredients for the methane formation of the bark. The concentration of steam-volatile organic acids serves as a control. The invention can be used in plants of industrial animal production as well as plants in which guelle anfaellt.

Description

Title of the invention

Process for the production of biogas from manure

Field of application of the invention

The invention relates to an intensive process for the production of biogas from manure, in particular cattle and pig manure while reducing undesirable ingredients. The invention belongs to the field of technical microbiology and can be used in industrial animal production facilities and all facilities in which manure is produced.

 Characteristic of the known technical solutions

-Höben the known conventional one-stage process for anaerobic manure processing two-stage processes are developed to increase the methane yield based on a reactor volume unit. These two-stage processes work on the principle of separation of acidity level and methane level, which can achieve much higher fermentation performance than with known single-stage processes. In the fermenter described in DE 2,939,169, the methane-producing reactor is additionally assigned an acid reactor in which the wastewater to be treated is subjected to pre-acidification prior to the actual methane production. The filling of the acidic eak gate takes place periodically, the residence time is 3 days, with heating is necessary.

According to a process (DB 3 102 739), acid and methane fermentation proceed separately in time and in space. The principle of two-phase separation is realized in a round fermenter with a 'ring' annular chamber for the first stage.

According to this basic principle of the separation of acidic and alkaline fermentation either by two independent reactors or by separation of a reactor into two spaces, all invention descriptions which claim to have a two- or multi-stage fermentation process (DB-OS 2,821,796, US Pat 4 022 665, US Pat. No. 4,318,993, US Pat. No. 4,040,953, US Pat. No. 4,053,395, US Pat. No. 4,067,801, CH-PS 4 95 3Q2, GB-AS 2 013 170). Volume ratios between acid and methane reactor of 1: 5 to 1:10 are given.

Accordingly, these processes have the disadvantage that between TO % and 20 % of the reactor volume for the actual methane fermentation can not be used or additional reactors must be built. In many cases, the acid stage is provided with heating and homogenizing means, which means an additional need for process energy. In addition, the control of the process is particularly difficult complicated by internals in two-chamber reactors.

Object of the invention

The aim of the invention is the production of biogas with a high biogas formation rate with optimum utilization of the available reactor volume from liquid manure and the discharge of manure with respect to polluting ingredients.

Explanation of the essence of the invention

The object of the invention is to use the organic ingredients present in the manure in a high-speed intensive process at maximum for microbial biogas synthesis. .

According to the invention the object is achieved in that the substrate inhibition of the, methane bacteria is kinetically controlled by the Säurebilduhg is performed separately from the methane formation, and that no additional reactor volume is required for the acid formation.

Through this control, using the readily determinable steam-volatile organic acids as a controlled variable, maximum microbial biogas synthesis is achieved with simultaneous maximum degradation of organic and inorganic contents by means of bacteria.

The decomposition of the organic ingredients is determinable via the BOD ₁ - and can be 90 % .

In the solution of the problem already known elements of anaerobic slurry cleaning technologies are so modified and further developed that results in a total of a closed Verfahrenszug in which the first process stage already runs within the stable systems or «during the pre-stacking / intermediate storage. Each process section has a specific share in the fermentation process ·

The main idea of the E _r findun.g. is to realize an intensive process without additional building work and ao realize the objective not only in principle, but also material and energy management and thus economically acceptable »

In the method according to the invention, the utilization of the ingredients of the manure is carried out by a two-stage continuous intensive fermentation, cfie first stage in the neutral range at temperatures of 10 ⁰ C to 20 ⁰ C, the second in the weakly alkaline at temperatures of 25 ⁰ C to 36 ⁰ C. With such a selective process control, the substrate inhibition of the methane bacteria by lower organic acids (acetic acid) or its salts is controllable, which significantly increases the degradation efficiency of the system and significantly contributes to a better utilization of a given reactor volume »or» higher space loads for the process design allows methane production *

In the method, the process is controlled in such a way that the specific target value specified in detail is reached for each process stage.

The fermentation process is characterized by a temperature of 10 ⁰ C to 2O ⁰ C for the acidic phase

- a pH between 6 and 8 for the acid phase

- a residence time of 10 to 15 days for the acid phase

- A temperature of 24 ⁰ C to 36 ⁰ C, preferably 3O ⁰ C to 35 ⁰ G for the alkaline phase

- a pH between 7 »5 and 9 for the alkaline phase

a residence time of 5 to 8 days for the alkaline phase. - '.. ·. , · ·

The main advantages of the process over currently used anaerobic slurry processing methods are:

- Effective use of the biogas reactor for the actual methane fermentation with high space-time yields and extensive elimination of undesirable ingredients of manure

- No additional construction costs for acid fermentation through use of existing demilitarization systems or existing storage basins

- Stable fermentation process under defined constant conditions by kinetic control of methane formation

Shortening of the residence time of the reaction mass in the reactor to half and more

Exemplary embodiment _i

The slurry used in the process example comes from an industrial young cattle plant. The size and the methods of animal husbandry including the applied petting regime require a certain composition of the composition of the raw manure. The fresh raw manure has a dry matter content of 8 to 12 % with a concentration of volatile organic acids between 1.4 g / l and 1.8 g / l *

In storage under laboratory and practical conditions, it has been determined that acid fermentation increases the concentration of steam-volatile organic acids to 3> 5 to 6 g / l after 10 to 15 days. -.

In practical operation, the liquid manure is conveyed from the sampling pit only after reaching this concentration and is fed to the fermentor. The pre-acidified manure can be characterized by the following mean substance characteristics: TS 9Q »8 g / 1; OTS 72.0 g / l; _cps 3.75 g / l; % 2.7 g / l; BhJ-I 1.3 g / l; BOD ₅ 8.4 g / l; pH 7 _? 5. *. , .

The fermentation proceeds at a temperature of 33 ^° C., a pH of 7.9 and a mean residence time of 7.5 or 5 days, the concentration of the steam-volatile organic acids is in the optimum range of 1.2 g / l · The ferment orauslauf u _# ä · described by the following parameters (mean values, mean residence time 7.5 days): TS 78.8 g / 1; OTS 60.8 g / l; _cps 1.2 g / l; ^ 2.7 g / l; WhJ.N 1.0 g / l; BOD ₅ 2.8 g / l. ^J '

The specific biogas yield (based on the unit volume of Reaktionsmasae) is at e-iner average residence time of 7.5 days 1.6 nr per m ^ reaction volume and day, at 5 days 2 m per m reaction volume and day · ', The methane content in Biogas produced is 55 to 60%, the reduction of BOD _C is 77 or 61% ♦

Claims (2)

- ..6 .... ". · Introduction 1. A process for the production of biogas from liquid manure in two successive stages, the acidity level and the methane level, characterized in that for the acid fermentation daa dung system of the cowsheds or another for the slurry technology anyway required container is used, that a fermentation temperature of 5 ⁰ G is maintained to 25 ⁰ C, preferably 1O ⁰ C to 2O ⁰ C that the treatment time 5 bia 30 days, preferably 10 to 15 days? in that the pretreated substrate having a dry substance content of 3 to 15 % is furthermore fed to a closed container reactor with homogenizing device, and that in this container at a residence time of 3 to 15 days at a temperature of preferably 24 ⁰ C to 36 ⁰ C a part of the organic substance contained in the pre-acidified manure is converted into methane and carbon dioxide. 2, Process for the production of biogas from manure according to point 1, characterized in that the process proceeds in a regulated manner and serves as a controlled variable the concentration of steam-volatile organic acids