Opportunities of biogas production from dairy wastewater 2014 Kristóf Szabó

Introduction  Biogas: -made at anaerobic circumstances -renewable energy source -biogas contains CO 2 and CH 4 -formation: hydrolisis=>acetogenesis=>methanogenesis -gas production depends on: pH, temperature, carbon:nitrogen ratio

Dairy wastewater  Has high organic matter content  It is hard to fermentate without adding other organic matter  Its lactose and fat concent is relatively low  Compared to the lactose and fat content, its protein content is higher

Aim of the experiment  Compare of microbe cultures  Determine the ideal concentration of the inoculum  Examine the gas production from model wastewaters, containing glucose and lactose, at anaerob circumstances  Examine the changing of gas production from model dairy wastewaters with pre-setted basic pH at anaerobic circumstances

Equipments and materials  Equipments: - Armfield anaerobic digester - Oxitop laboratory fermentation system  Used materials: - model wastewater containing glucose ( 8 g/l glucose and other trace elements) - model dairy wastewater (3 g/l and 6g/l milk powder) -concentratum of 3 g/l milk powder solution (concentrated with 10 kDa ultrafiltration to its half cubic content) - decomposited wastewater sludge - Microcat-UASB microorganism culture

Armfield digester from front- wise Armfield digester from side-view Oxitop machine

Results 1. Examination of inoculum-wastewater sludge Cumulative gas quantity from decomposed watewater sludge The changing of pH through the experiment Equipment: Armfield Model wastewater: glucose-containing

Examination of inoculum- Microcat-UASB Equipment: Armfield Model wastewater: glucose-containing Cumulative gas quantity with Microcat UASB The changing of pH through the experiment

2. Examination of the inoculum’s homogenity and concentration Equipment: Oxitop Model wastewater: glucose-containing Gas production at different concentration and homogenity of the inoculum

Biogas production at different concentrati on Biogas production at different concentration, calculated to unit inoculum mass (mg/ml)

3. Effect of the concentration of the inoculum Equipment: Oxitop Model wastewater: glucose-containing

Effect of the concentration of the inoculum to the methane production

4. Examination of the effect of pH to the gas production from dairy model wastewaters Equipment: Oxitop Model wastewater: lactose-containing Gainable biogas quantity from pH-controlled and non- controlled solutions Gainable methane quantity from pH-controlled and non- controlled solutions

5. Examination of the pH effect to the gas production from ultrafiltrated dairy model wastewaters Gainable biogas quantity from pH-controlled (pH=9) and non-controlled solutions Gainable methane quantity from pH-controlled (pH=9) and non-controlled solutions

Summary Homogeneous sampling from inoculum gives higher gas production Optimal inoculum concentration was 15 mg/100 ml; higher concentration is not giving proportionately higher gas production Milk powder’s concentration does not affect to the gas production significantly if milk powder solutions has the same pH at the beginning Higher pH gives higher gas production Concentrate of the ultrafiltered milk powder’s solution (with higher protein content) as good gas production can be achieved as the solution that has the same concentration before ultrafiltration

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