Separating biogenic waste products into liquids and solids
Biodegradable waste refers to biowaste that is collected separately. Just like kitchen waste and leftover food from catering establishments, as well as out-of-date packaged foods, biodegradable waste can be separated into solid and liquid fractions with the aid of Doppstadt’s screw press.
The bioavailable components are enriched in the liquid phase and can be fed to a wet fermenter. As a result of the gentle preparation and pressing step, the digestate usually does not need any further processing and already contains less than 0.5 % contaminants upstream of the fermenter, based on dry matter. The solid phase mainly consists of packaging material and other solids. The contained residual organic materials are implemented as part of a biological drying process. After subsequent screening, residual packaging can be incinerated. The fine fraction is clean compost.
In cases where a dry fermenter is used, the screw press can make the digestate stackable and thus easy to store, by removing the pumpable liquid phase. This moreover ensures the permeability required for the subsequent composting. The Doppstadt mixer can mix the digestate’s solid matter fraction from the press with green waste before it is supplied to the rotting process. This ensures a more intensive rotting process and thus a better level of rotting.
For turning aerated trapezoidal and static windrows of up to 3.5 m in height, Doppstadt’s DU windrow turner is a cost-effective solution that is not sensitive to contaminants. The raw compost can be classified after the rotting process with the aid of Doppstadt’s SM screening machine, which prepares the finished compost.
The solid/liquid separation of biodegradable waste does not focus mainly on extracting as much potential biogas as possible from the feed material, but rather on providing a clean biogas substrate with one machine without any pretreatment, which does not require any further post-treatment after the fermenter.
The Process at a glance
- Prevention of plastics already present in the fermentation substrate
- Rugged solid/liquid separation, contaminant-tolerant volume diagonals of up to 80 mm
- No additional full flow screening of digestate necessary
- Ideal, fast subsequent rotting by adjusting the pH value and structural percentage