Smallholder Biogas Deployment in Northern Thailand: A Flexible Digester Project by Henan Zonghai Plastic Industry

Project Background

Across Southeast Asia, smallholder livestock farms produce a steady supply of organic waste that can be converted into renewable energy through anaerobic digestion. However, the adoption of biogas systems among smaller farms is often limited by installation costs, construction complexity, and site conditions.

In 2024, Henan Zonghai Plastic Industry Co., Ltd., a manufacturer specializing in flexible environmental storage systems, participated in a rural biogas installation project in northern Thailand. The project focused on supporting pig-raising households seeking a practical way to manage livestock manure while generating fuel for cooking.

The initiative provided an opportunity to evaluate how flexible membrane biogas digesters perform under typical Southeast Asian farming conditions.

Local Farming Conditions

The participating farm was located in a rural agricultural area where mixed farming is common. The household raised approximately 18 pigs, producing manure that was previously stored in open pits near the animal housing area.

Key environmental characteristics included:

• Average annual temperature: 26–32°C
• High seasonal rainfall during the monsoon season
• Clay-rich soil with moderate groundwater levels

These conditions made the construction of traditional underground brick digesters difficult. Excavation work during the rainy season frequently resulted in soil collapse and water infiltration.

The farm therefore required a system that could operate reliably while minimizing construction requirements.

Identifying the Challenge

Prior to installing the digester system, the farm faced three main operational challenges:

1. Waste accumulation near livestock housing

Pig manure collected daily was temporarily stored in a shallow pit. During heavy rain, slurry could overflow into surrounding soil.

2. Dependence on purchased cooking fuel

The household relied primarily on LPG cylinders for cooking, which required regular delivery from nearby towns.

3. Limited construction resources

Building a fixed concrete digester would have required skilled labor and several weeks of work, increasing project complexity.

The objective of the project was therefore to install a compact, durable biogas system that could be implemented quickly and maintained with basic farm management practices.

Technical Solution Provided by Henan Zonghai Plastic Industry

Henan Zonghai Plastic Industry supplied a flexible biogas digester system with a working volume of 12 cubic meters, suitable for farms raising 10–25 pigs.

The digester body was manufactured using reinforced PVC-coated polyester fabric, a material designed for outdoor environmental applications.

Key technical specifications included:

Membrane thickness

Approximately 0.9 mm multilayer composite structure

Base fabric reinforcement

High-strength polyester fibers providing tensile stability against internal gas pressure

Seam technology

High-frequency welded seams designed to maintain airtight gas containment

Operating temperature tolerance

Approximately −30°C to 70°C, supporting stable performance in tropical climates

The digester system included:

• Feedstock inlet pipe
• Slurry outlet pipe
• Gas outlet connection
• Low-pressure gas pipeline for kitchen use

Because the structure was flexible, the unit could be installed above ground on a compacted soil base with partial soil covering for stability.

Installation Process

Installation of the digester required only a small prepared area adjacent to the livestock shed.

The process involved:

1. Leveling the installation site
2. Placing the digester body and securing anchor points
3. Connecting the inlet pipe to the manure collection channel
4. Installing the outlet pipe for slurry discharge
5. Connecting the gas pipeline to a household stove

The entire installation process was completed within one working day, requiring only basic hand tools.

This rapid installation was particularly important because it avoided extended construction work during the rainy season.

Operational Conditions

Once the system was operational, the farm began feeding the digester with a mixture of pig manure and water.

Typical daily inputs included:

• Manure: 10–14 kg per day
• Dilution water ratio: approximately 1:1

Under the region’s natural temperature range of 28–32°C, anaerobic microorganisms began converting organic matter into biogas without any heating equipment.

Gas produced in the digester was routed through a low-pressure pipeline to the household kitchen.

The fermentation process also generated liquid digestate that exited through the outlet pipe into a small collection pit.

Observed Farm-Level Results

Over several months of operation, the system demonstrated practical benefits for the farm.

Waste management

Manure that was previously stored in open pits was now processed directly through the digester.

Household energy

Biogas generated from daily manure inputs provided fuel for routine cooking activities.

Agricultural reuse

The digested slurry was applied to vegetable crops grown near the house.

These outcomes illustrated how small-scale digesters can integrate with everyday farm operations without requiring complex infrastructure.

Industry Insight

Projects such as this highlight the importance of adapting biogas technology to local agricultural conditions. In Southeast Asia, where small farms dominate rural landscapes, technologies that reduce installation barriers can help expand the use of organic waste treatment systems.

Flexible digester systems manufactured by companies like Henan Zonghai Plastic Industry Co., Ltd. demonstrate how modern polymer materials can simplify deployment while maintaining the technical requirements necessary for anaerobic fermentation.

As rural energy programs continue to evolve, practical case studies from farms in Thailand and neighboring countries provide valuable reference points for future installations.