If you go too small you end up with a backlog of manure and a compliance risk. If you go too large you waste investment on equipment, with depreciation costs eating away at your profits. The capacity choice of an animal manure fermentation tank is essentially a math problem related to your farm size, but many farms don’t do the math before buying equipment.

This article will teach you how to quickly estimate the size of tank you will require.

Before Selecting, Determine Three Numbers

There is no need to do complex process calculation for animal manure fermentation tank selection, you only need to clarify three core parameters:

First manure production per day. This is the starting point of the calculation and depends on the size of your farm and the way you gather your manure. The amount of manure produced per animal per day can vary greatly depending on the type of livestock and the age of the animal.

Secondly, fermentation cycle. Bolong vertical aerobic fermentation tank, the fermentation cycle is about 7 to 10 days. The turnover efficiency of enclosed animal manure fermentation tanks is improved by an order of magnitude compared to the 60-90 days of traditional open composting. This is why its footprint is much smaller than traditional composting solutions for the same processing capacity.

Third, safety margin. In actual selection, it is recommended to leave an additional 20%–30% margin on top of the theoretical calculation value to provide fermentation space during actual operation.

Once these three numbers are determined, the required tank volume becomes clear.

Choosing a Fermentation Tank: Volume Is Just the Threshold, the Real Differences Lie in These Three Points

The differences between animal manure fermentation tanks are not just about volume, but also about the equipment’s adaptability to raw materials, stability of discharge indicators, and long-term labor and energy consumption costs. The Bolong 11FFG series of enclosed aerobic fermentation tanks focuses on three core advantages:

1、Wider adaptability to raw materials. Traditional composting has strict requirements for C/N ratio and moisture content; raw materials like chicken manure, which has a seriously low C/N ratio, require large amounts of additives to ferment. Bolong animal manure fermentation tanks, through the coordination of forced ventilation, precise temperature control, and agitation systems, allow chicken manure to be fed directly into the tank without additives as long as the moisture content is controlled below 65%—this means for high-nitrogen raw materials like chicken manure, the labor, time, and material costs of the mixing process are eliminated.

2、Stability of discharge indicators. The insulated design of the enclosed tank avoids common surface heat loss and uneven temperature issues found in open composting, keeping the temperature curve stable throughout the fermentation cycle. Third-party test results from actual Bolong animal manure fermentation tank discharge show: organic matter content 52%, total nutrients (N+P₂O₅+K₂O) 11.9%, fecal coliform negative, ascaris eggs not detected, and heavy metal content far below national standard limits—this stability is difficult to achieve with open composting.

3、Small footprint, labor saving, and low long-term cost. Bolong animal manure fermentation tanks have a fermentation cycle of about 7 days. Compared with the traditional 90-day composting, the equipment footprint and volume are greatly reduced for the same processing capacity. The entire system comes standard with fully automatic control and waste heat recovery; daily operation requires only one person, basically eliminating the labor costs of more than five people required for traditional composting.

In addition, the Bolong 11FFG series offers multiple product models from 102 m³ to 280 m³, meeting the needs of farms of various scales. For extra-large-scale farms, a parallel configuration of 2–3 units can also be used.

For precise matching of specific models with your farm scale, please contact the Bolong technical team for one-to-one selection solutions based on daily manure output, moisture content, and raw material type.

Three Common Pitfalls in Selection

Pitfall 1: One extra-large unit is not as good as multiple parallel units. For large-scale farms, it is recommended to choose 2–3 medium-sized units running in parallel rather than one extra-large unit. Single-point failures do not affect overall operation; maintenance can be carried out in rotation without manure backlog; and batch feeding is more flexible, adapting to fermentation needs of different manure types.

Pitfall 2: Underestimating the impact of moisture content. Compared with chicken manure at 65% moisture content, chicken manure at 80% moisture content can have a volume difference of more than 30% for the same weight. The upper moisture content limit for Bolong animal manure fermentation tanks processing chicken manure is 65%; if it exceeds this, it needs to be dehydrated first or pretreated with additives such as straw and rice husks before entering the tank.

Pitfall 3: Only looking at price without considering supporting systems. When selecting equipment, supporting indicators such as installed power, daily water consumption, whether an odor removal system is included, and automation level should also be evaluated.

Selection Is Not Complicated; the Key Is to Calculate Based on Scale

The capacity selection of an animal manure fermentation tank is the step most worth calculating in advance in the entire procurement decision—it determines how much manure you can process, how much investment is needed, and whether the equipment can match your farm scale in the long term.

Bolong can provide feed ratio recommendations and enclosed aerobic fermentation tank selection support based on your manure raw material type. Please contact us.