자가발열 혐기-호기 소화공정을 이용한 가축분뇨의 자원화 = Resource recovery from livestock wastewater by autothermal anaerobic-aerobic digestion process

다국어 초록 (Multilingual Abstract)

Livestock wastewater is a kind of high-concentrated organic wastewater, so it is treated by anaerobic digestion process because aerobic treatment has a lot of restrictions in technical aspect.
Anaerobic process is possible to decompose the organic matters and this process generate end-sludge product a little. Futhermore, it can remove intestinal parasites and produces the bio-gas which contains methane
Generated bio-gas by anaerobic digestion contains methane that is more than 60% of total amount, so it can collected for good energy, moreover treated sludge dose not have any odor. Therefore, anaerobic process is in the limelight on the world cause it is good enough for alternative energy system and reducing greenhouse gas.
In spite of these advantages, bio-gas plant using livestock wastewater could not come into wide use in Korea. It was because of design failures and maintenance problem, and not enough to treat a digested sludge, and there was no effective technology of generated bio-gas. Also, temperature is another problem to apply anaerobic system because about 5 months fall down below zero in Korea, therefore an optimum temperature maintenance for ideal methane gas production by anaerobic system, 35degree, is difficult and inefficient.
This study releases the new-type process 'autothermal aerobic-anaerobic digestion process' that autothermal aerobic reactor is combined structurally to anaerobic reactor.
This new-typed process is designed on the other way. Digested sludge that is passed through anaerobic reactor at first moves to autothermal-aerobic reactor later, so it can improve gas-production and do not need further facilities such as heat-exchanger. And final treatment process is liquid fertilizer process that is applied bacillus sp., so there is no secondary problem of anaerobic digested sludge.
The object of this study is to confirm a thermal efficiency from autothermal process and demonstrate that generated heat from autothermal aerobic process can provide a optimum temperature for operating anaerobic process. And it is also to check that if it is possible to increase a temperature or not when additionary raw livestock wastewater is injected to autothermal aerobic reactor.
This study indicates an optimum operation conditions for liquid-fertilizer production by Bacillus sp. that is applied to autothermal aerobic process. And also, odor removal effectiveness and appropriate nutrient contents for liquid fertilizer availability.
As a result, if reactors were maintained a regular temperature, gas production was very stable and methane content was 65~70% in the total gas amount. So it is very effective for Energy Conversion.
It is also possible to increase reactor temperature by increasing autothermal amount through additional raw livestock wastewater injection, so gas production would be much more increased. It means that applicability of new-typed process is very affirmative without any additional heat energy.
This result indicates that as a result of liquid fertilizer, every mode was satisfied the official standard of commercial fertilizer of water, N, P, K, heavy metal and odor level.
In case of odor removal efficiency, especially, this result shows that bacillus sp. has a great efficiency that is its unique characteristic to remove odor material such as H2S and NH3. There was unusual thing that delicate soil smell was checked. It substantiates that characteristic of bacillus sp., one kind of soil microbe, was reflected in this result.
In case of Mode 3, however, salt was over the required amount (acceptable standards, 0.3%). When salt is accumulated on the ground, it becomes stiff and turn to acid soil, so follow-up process has to be considered to remove salt for liquid fertilizer.
This study says that if economics, bio-gas production and liquid fertilizer production are considered, Mode 2 is the most appropriate operation. It also indicates that it is possible to increase heating energy through the direct-inflow of raw livestock wastewater to the autothermal aerobic reactor when heat energy is deficient.

목차 (Table of Contents)

• 목 차
• List of Tables ⅲ
• List of Figures ⅵ
• 제1장 서 론 1
• 1.1 연구의 필요성 1
• 1.2 연구의 목적 6
• 1.3 연구의 범위 7
• 제2장 이론적 배경 8
• 2.1 가축분뇨의 발생 및 처리현황 8
• 2.2 혐기성 소화의 원리 11
• 2.3 혐기성 소화의 영향인자 19
• 2.4 자가발열 고온호기성소화의 원리 29
• 2.5 가축분뇨의 액비화 37
• 2.6 부숙도 55
• 2.7 Bacillus sp.의 분류 및 특성 58
• 제3장 실험장치 및 분석방법 69
• 3.1 실험장치 및 운전조건 69
• 3.2 분석방법 74
• 제4장 결과 및 고찰 80
• 4.1 유입수의 성상 80
• 4.2 온도의 변화 및 DO농도 81
• 4.3 pH 및 알칼리도 85
• 4.4 BOD농도의 변화 90
• 4.5 TCOD농도와 SCOD농도의 변화 93
• 4.6 고형물 농도의 변화 103
• 4.7 TVFAs농도의 변화 107
• 4.8 T-N농도 및 T-P농도의 변화 109
• 4.9 가스의 발생 및 물질수지 분석 115
• 4.10 SVI의 변화 121
• 4.11 가축분뇨의 액비분석 122
• 4.12 악취의 제거 130
• 4.13 부숙도 판정 131
• 4.14 미생물 동정 145
• 제5장 결 론 157
• 참 고 문 헌 163
• ABSTRACT 182