WAMITAB - Chartered Institution of Wastes Management Waste Treatment Processes Questions and Answers

Question 1

An Energy from Waste (EfW) facility processes municipal solid waste. The process generates two main solid residues: Incinerator Bottom Ash (IBA) and Air Pollution Control residues (APCr). How should these two waste streams be managed immediately after production?

Accepted Answer

IBA can be processed for recovery as a secondary aggregate, while APCr must be treated and disposed of as hazardous waste.

Answer

Incinerator Bottom Ash (IBA) is the non-combustible residue from the furnace. After processing to remove metals and mature it, it can often be used as a secondary aggregate in construction. In contrast, Air Pollution Control residues (APCr), also known as fly ash, are captured from the flue gas treatment system and contain high concentrations of contaminants, classifying them as hazardous waste that requires specialised treatment and disposal.

Question 2

Which of the following are the two primary outputs of a successful anaerobic digestion (AD) process when treating source-segregated food waste?

Accepted Answer

Biogas and digestate

Answer

Anaerobic digestion is a biological process that breaks down organic matter in the absence of oxygen. The two main products are biogas, a mixture of methane and carbon dioxide which can be used for energy generation, and digestate, a nutrient-rich solid and liquid material that can be used as a biofertiliser.

Question 3

In a Materials Recovery Facility (MRF), what is the primary function of an eddy current separator?

Accepted Answer

To separate non-ferrous metals like aluminium cans from other materials.

Answer

An eddy current separator uses a powerful, rapidly rotating magnetic field to induce eddy currents in non-ferrous metals. These currents create a repulsive force that ejects the non-ferrous items (such as aluminium and copper) from the main waste stream, allowing for their effective separation.

Question 4

When treating catering waste containing meat in an In-Vessel Composting (IVC) facility, which critical control parameter must be met to comply with the Animal By-Products Regulations (ABPR)?

Accepted Answer

Achieving and maintaining a minimum temperature of 60-70°C for a specified period.

Answer

The Animal By-Products Regulations require a two-stage process or 'barrier' system to ensure the destruction of pathogens. A key part of this is the sanitisation stage, where the composting mass must reach a core temperature of 60-70°C and be held for a specified duration (e.g., 60°C for at least two days) to ensure all harmful bacteria are killed.

Question 5

Which statement best describes the fundamental principle of pyrolysis as a thermal waste treatment process?

Accepted Answer

The thermal decomposition of waste in the complete or near-complete absence of oxygen.

Answer

Pyrolysis is distinct from incineration and gasification because it is a thermochemical decomposition process that occurs in an oxygen-free or oxygen-starved environment. This prevents combustion and instead breaks down the material into solid (char), liquid (bio-oil), and gaseous (syngas) products.

WAMITAB - Chartered Institution of Wastes Management Certification Practice Test

WAMITAB - Chartered Institution of Wastes Management Certification Practice Test

WAMITAB - Chartered Institution of Wastes Management Waste Treatment Processes Questions and Answers