Initial Safety Consideration Assessment 2022

Running head: Initial Safety Consideration and Assessment
4.0 Initial Safety Consideration and Assessment

Initial Safety Consideration and Assessment
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4.1 Safety, Health, and Environmental Consideration
The safety, health, and environmental (EHS or SHE or HSE) impacts can be known as
systematic process procedure or tools that are used to identify the process impact on the health
and safety of workers as well as the environmental impact of the process (Koller et al., 2000).
The aim of this section is to investigate and identify the hazards and risks from substances and
equipment on workers and the environment. It can be performed through COSHH assessment,
HAZID study, and risk assessment for the wastewater treatment plant (WWTP), where the
purpose of HSE study is to mitigate any risk or hazard to protect the human, animals, and
environment.
4.2 COSHH Assessment and Environmental Impact
The COSHH assessment is concerned about identifying the hazards and risks from
substances that generated or used during the treatment of wastewater for human and environment
(Koller et al., 2000). The COSHH assessment is identified in Appendix 6.
4.3 Process Safety Study (HAZID)
Hazard identification (HAZID) study is an effective and professional tool to define,
assess, and mitigate the potential risk and hazard by providing recommendations. The assessment
of any hazard event is based on provided risk matrix (see Appendix 6) in terms of Severity (S),
likelihood (L), and risk rating (RR) (Koller et al., 2000). In addition, the expander, application,
and explanation of HAZID guide work can be shown in Appendix 6. The (HAZID) study of the
wastewater treatment can be presented also in Appendix 6.
4.4 DOW fire and explosion
DOW fire and explosion is a method developed by the Dow Chemical Company that can
be used for ranking the risk related to fire and explosion within a particular process. The analysts
are responsible for calculating the hazards and the explosion index with the use of material
characteristics and process data (Nezamodini, Rezvani & Kian, 2017). It is one of the popular
safety measure methods that has been designed to support in quantifying the risk or expected
damage from the potential for or explosion events in the real-time by the users and identification
of equipment that help in escalating the incident and communicating the fire and explosion risk
potential to the management of the Safety team.
4.5 Mitigating Strategy
Wastewater Treatment plants produce or require the use of toxic and/or combustible
substances. Chlorine and ammonia are commonly used substances to treat the Hydrogen Sulfide
(H2S). H2S is a deadly toxic gas, which is present in untreated wastewater that contains raw
sewage and also can be generated as a byproduct of sludge treatment processes. Methane gas is
produced as a byproduct of raw sewage and sludge digestion. Parts Per Million (ppm) monitors

Initial Safety Consideration and Assessment
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are typically used to alert workers and safety personnel if these toxic gases reach ppm levels
above the safe exposure levels as shown in Table 8.
Fire detections system consists of smoke detecting elements that are scattered all over the
plant, especially near the equipment that have a higher possibility of a fire breakout (e.g.
Digester, Biogas Holder and Thermal Hydrolysis reactor). If the smoke detectors detect smoke, a
loud fire alarm will be triggered notifying the workers to evacuate the plant and meet at the
proper assembly point as shown in the plant layout.
Wastewater treatment plants are designed to treat all municipal waste, the process of
waste treatment results in the byproduct of combustible and toxic gases. Toxic and combustible
gases that are produced on cite can accumulate in working areas or confined spaces, decreasing
oxygen amounts and making those areas extremely dangerous, these areas must be monitored on
a continuous basis to protect both personnel and the plant. Hazardous Gases that are found in the
plant can be shown in Table 8:
Table 1: Combustible and toxic gases that are found in the wastewater treatment plant
Combustible Gases Maximum Safe
Limit
Toxic Gases Maximum Safe limit
Methane (CH4) 1 ppm Hydrogen Sulfide
(H2S)
5 ppm
Pentane (C5H12) 120 ppm Carbon Monoxide
(CO2)
20 ppm
Hydrogen (H2) 100 ppm
A gas detection system is used in the wastewater treatment plant to monitor the whole
plant and detect any dangerous gases that are present to prevent the breakout of a fire or causing
harm to the workers. The wastewater treatment plant is fitted with a Fixed Gas Detection alarm
system, this system is integrated in the Building management system. Gas detection elements are
scattered all over the plant especially in working areas and confined spaces, these elements are
wired to a main screen in the control room. The main screen shows the levels of oxygen and if
there are any toxic gases present. If there are dangerous, gases present over the safe limit (see
table 8), an alarm will be triggered and the workers will evacuate the plant.
#.# Personal Protective Equipment
#.# General PPE
The workers on the site of a wastewater treatment need to consider wearing personal
protective equipment (PPE). The employees on the wastewater treatment site need to be aware
about how important the PPE is for them and how important it is to be safe on the site. The
workers need to be trained on how to use the PPE the right way and to make sure hands are
washed immediately with soap and water after removing the PPE.