Database of Waste Management Technologies Life

Temporary Storage 2: Storage in containers

 

Process Description

This is a Temporary Storage facility intended for separate collection of glass, but also for metals if is collected in small amounts and no baling is required.

  • A Reception Hall where trucks unload the materials on reinforced floor.
  • A front loader that pushes the materials into a hopper that feeds a chain conveyor. This conveyor leads materials to the hand-picking line which is a slowly moving conveyor in front of the hand-picking personnel. Personnel stand on a metal platform of about 5 m above the floor level. This hand-picking line includes a minimum number of people and is intended for the removal of unwanted material from the source separated recyclate. Unwanted material is removed by the personnel and discarded in silos placed under the platform.
  • At the end of the line (conveyor) the “clean” material is fed into a container.

Full containers are moved by fork-lift trucks and stored before the material is sold to recyclers.

The entire plant is housed in a building with reinforced floor and metal roof. Lighting and electrical installations are required as well as a fresh water supply system for cleaning and fire-fighting purposes.

Process Mass Flow Diagram

temp storage 2

Process Operational Data

Area

Sufficient space for the activities occurring at a Material Recover Facility is crucial. Site acreage should be large enough to accommodate the physical structure, pre-processing materials and post-processing products storage and orderly vehicle movement. In addition a buffer space with trees and shrubs will help improve aesthetics and decrease noise.

The amount and location (indoors, outdoors) of space allocated to product storage is influenced, in great degree, by the markets. The market specifications will influence whether or not the products may be stored outdoors pending shipment, while the market demand of recovered materials will determine the storage capacity of the facility. Although each facility must be sized for materials storage in accordance with individual site-specific criteria, it is prudent to provide sufficient storage capacity to hold processed materials for one week up to one month (EPA, 1991; Tchobanoglous, 2002). The sitting requirements, according to data from existing facilities in United States, vary greatly ranging from 5m2/TPD (tonnes per day) to 40m2/TPD depending on the capacity and degree of mechanization for materials separation (Dubanowitz, 2000), while Golder Associates Ltd (2009) reports 0.30 m2 per tonne of waste per year.

Energy

Energy usage of Material Recovery facilities includes mainly:

  • Electricity used for the operation of motors (conveyers, balers), ranging from 15 to 20 kWh per tonne of feedstock depending on the degree of mechanization (EPA, 1991)
  • Diesel used for heating and vehicle (front loaders and forklifts) movement, estimated at 7.7 kWh per tonne of feedstock (EPA, 1991).

Water

Material Recovery facilities use water only for buildings and equipment cleaning and for personnel needs. According to EPA water usage ranging from 0.05 to 0.2 m3 per tonne of feedstock (EPA, 1991) depending on the capacity.

Process Environmental Indices

Air Emissions

The main environmental issue related to air quality arising from the operation of Temporary Storage Facilities is dust emissions from tipping operations, storage and loading operations. Operations are usually conducted indoors where ventilation and localized dust suppression measures are taken as required for stationary sources. Dust emissions data from this type of facilities are largely unavailable, but it is estimated that are not significant.

Wastewater

The Temporary Storage facilities for separately collected materials are constructed on a concrete pad that prevents seepage of any waste pollutants into the soils. Moreover, these facilities typically handle pre-cleaned, dry and solid components of the waste stream, which often is prewashed by the waste generator of food and other organic residues. Thus, the only wastewater generated is from cleaning processes and personnel and it is estimated that it is equal to water consumed.

Residual

The solid wastes of Temporary Storage Facilities include mainly residual non-recyclable wastes which are removed from the source separated recyclate with handpicking. Residual of Temporary Storage facilities is Municipal Solid Waste and it is landfilled. According to data from existing facilities residual is up to 0.1 tonnes per tonne of feedstock (EPA, 1991).