Alternative Composting Methods
Past history of large composting facilities have shown many to be fraught with problems which have proven insurmountable and have caused project failures.
Tunnel
When hearing or reading any of the following statements describing a composting systems performance, understand that even though they have some degree of truth, they are basically false statements.
It is important to question when statements like those below are made regarding composting; it will help to avoid major future project design, operating, and performance failures.
1.
Composting is odor free
2.
Composting can be accomplished in a few days by using a magic Black Box or by using a Super innoculant, and then cured for a few weeks.
3.
Composting on a large scale only requires a few acres of land and equipment to move piles.
4.
Composting greatly reduces waste volume.
A successful composting plant design is based on many factors. Discounting the potential negative aspects, by believing the above statements, can result in a multi-million dollar project failure.
Odor, volatile organic compounds, and ammonia accompany the steam which leaves these composting piles to the surrounding environment.
Many composting processes only use inefficient static piles for composting after an initial pre-preparation stage. A composting plant is a production line and can have no weak links. Weak links will result in odors, extended composting time, low production rates, high operating costs, etc. Any of these problems can lead to a project failure. Negative effects from a poorly designed aeration and material handling system can quickly become insurmountable when processing hundreds of tons of waste.
When reviewing any composting process ask the following basic questions when comparing different processes:
1.
What is the true amount of organic waste composted?
This means after the waste sorting and without watered down sludge, being mostly water weight, being added to falsely bolster plant performance.
2.
What is the actual amount of compost produced daily?
Remember the volume of waste going into a facility closely matches the volume leaving as finished compost. If a facility produces a 100 cubic meters of compost; it only processed approximately 100 cubic yards of solid waste after it has been pre-processed.
3.
What is the total composting process time? Does this included so called cure time?
4.
Are static piles used in composting and curing?
Static piles are slow and inefficient. At least 60 to 90 days are required to stabilize waste composted with this method. The longer the composting process takes to stabilize the compost the larger the facility becomes, more odor is produced, and the more costly it is to operate.
5.
What is the capital and operating cost per ton of compost produced?
6.
Does the total energy cost include; ventilation, odor control, manpower, and mobile loading equipment .
7.
What is the total volume of air required to be processed for odor control and how is the air treated to remove odor.
In an inefficient compost plant design, the capital and operating cost for an odor control system is significant because of the total volume required to be processed.
The answers to these questions will allow a more thorough process review. The problem with composting is that even the simplest backyard compost pile will eventually produce compost. All of the alternate composting methods shown will produce compost. The question is at what final cost? Let's first look at what some people view as the least expensive method of composting; Static Piles (Windrows). But is it really inexpensive when you look at all the real world factors?

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