Opportunities of biogas production from dairy wastewater

2014

Kristóf Szabó

Introduction

Biogas: -made at anaerobic circumstances-renewable energy source-biogas contains CO2 and CH4

-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

Results1. Examination of inoculum-wastewater sludge

Cumulative gas quantity from decomposed watewater sludge

The changing of pH through the experiment

Equipment: ArmfieldModel wastewater: glucose-containing

Examination of inoculum- Microcat-UASBEquipment: ArmfieldModel wastewater: glucose-containing

Cumulative gas quantity with Microcat UASBThe changing of pH through the experiment

2. Examination of the inoculum’s homogenity and concentration

Equipment: OxitopModel wastewater: glucose-containing

Gas production at different concentration and homogenity of the inoculum

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

3. Effect of the concentration of the inoculumEquipment: OxitopModel 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: OxitopModel 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 solutionsGainable 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

Thank you for your attention!