Essay: Risks and hazards at wastewater treatment plants

Wastewater refers to the spent water that is discharged by sources such as domestic (homes), commercial (shopping malls), industrial (factories), infiltration and inflow (pipes) and stormwater (excessive rainfall/snow melts). It consists of 99% of water and 1% waste. Depending on the sources, the wastes may include organic matter (human faeces), detergents, heavy metals, solid matter, microorganisms and floating debris among others. Sewer systems involving drains, pipes, and pumps then carry the wastewater to a treatment facility.
Wastewater treatment plants are very important. Their role is to remove as much as possible the amount of pollutants and solids from the wastewater, restore its pH and disinfect it before discharging in water bodies such as rivers and seas. This process is carried out within technical and financial feasibility. Therefore, the treatment of wastewater is primordial; otherwise, the polluted water will infect fresh water bodies, disrupting their ecological balance and endangering the flore and fauna.

Furthermore, processes taking place in wastewater treatment plants pertain to physical, chemical and biological methods. The latter involve the use of harmful substances which can cause damage to the Health and Safety of the workers. The existence of hazardous substances at work does not only affect the workers’ health; depending on the effect of the illness, it may significantly reduces their capacity to respond to external situmili thereby preventing them to carry out their duty at an optimum level .As such, this can lead to industrial accidents (Chatziioannou, 2012).

As a matter of fact, the risk factors are:

Physical

This involves risks involving the layout and infrastructure of the wastewater treatment plant such as confined spaces, faulty electrical equipment, slippery surfaces, collapse of guard rails.

Chemical

It pertains to the use of chemicals and emission of harmful gases such as hydrogen sulphide, ammonia along with the use of chlorine for the treatment of the wastewater.

Biological

This factor includes microorganisms which are present in sewage to which the workers are exposed to them at the wastewater treatment plant.

Moreover, other than the workers, the operation of a wastewater treatment plant also has an impact on:

• Health and Safety of the residential areas nearby the residential areas nearby in terms of aesthetics, odour, noise, and flies/pests.
• Environment in terms of discharge of untreated chemicals resulting in water pollution and aerial dispersion of wastewater resulting in air pollution

Health and safety risks & Assessment of their Effects

As introduced in section 1, the risks involved in the treatment of waste water are can be subdivided into 3 broad categories as shown below:
Basically, the emergence of risks can be attributed to the chemicals used in the treatment process and to the design of the plant itself. Moreover, the sewage material constitute of a significant amount of microbes, which can potentially have negative health impacts on the workers being exposed to sewage. Hence, this further leads to more risks.

3.1 Factors posing health and safety risks

3.1.1 Physical risks and factors

The probability of encountering a physical hazard when working at a waste water treatment is very high. Unless precautionary measures and extreme care are taken, the consequence of being confronted with such risks can be irremediable, long lasting and disastrous as well. The magnitude of the harm caused when exposed to a hazard varies significantly depending upon the design of the plant.

• Risks
• Physical
• Chemical
• Microbial

The factors posing physical risks pertaining to Health and Safety are described as follows:

1. Compact spaces

The majority of the treatment plants are crammed with equipment and machinery. Consequently, there is inadequate working space. For instance, the sedimentation tanks, underground and below grade vaults have restricted access. All of these constitute a major hazard as trips and falls are very likely to occur. (Stellman 2011)

Furthermore, the size of openings in manholes is usually not adequate. Hence, this can be an obstacle to egress in the event of an emergency.
The figure below depicts a manhole with limited space for entry and egress.

Figure 3-1 Manhole with cover removed

2. Confined spaces

There is insufficient ventilation in the working areas at the treatment plant as these are confined. Consequently, the workers are constantly being exposed to an environment with low oxygen concentration.

Moreover, there is the risk of exposure to high levels of toxic gases such as hydrogen sulphide, methane gas and ammonia. This can potentially lead to serious illness and death as well.

3. Mishandling of equipment

Severe injuries may arise when the mixing equipment, sludge rakes and pumps (amongst other mechanical devices) are not handled correctly and with care. Unintended energizing of machinery may also be a common occurrence and if this happens during servicing, the worker can be seriously wounded or may even be killed.

4. Faulty electrical equipment

There is an ever present risk of an electric shock occurring at the treatment plant and this can be caused by contact with faulty electrical equipment and cables. Also, Working with electrical equipment in a wet condition can be a hazard.

5. Slippery surfaces

It is commonplace to find water puddles at the treatment plant. Hence, the probability of slipping and falling on the floor is very high.

6. Collapse of guard rails

The guard rail, if not in proper repair, may collapse in case the worker inadvertently leans over it. As such, there is the risk of drowning in the treatment tanks.

7. Handling heavy loads

In wastewater treatment plant there is the use of heavy load which may cause injury.

8. Risk of fall

• There is a risk of falling if work is being done at a considerable height over an unguarded tank.
• There may be accidental fall when grates are lifted over waterways and tanks for access.

9. Machineries with moving parts

Pumps and valves are involved for moving water. There are also many moving parts like screens and conveyors which remove debris and move sludge. This equipment may cause caught/ crush hazard if accidentally a hand, arm or foot is placed near the moving part. (Statefundca, n.d)

3.1.2 Microbial risks and factors

During the treatment of waste water, workers are exposed to disease causing microorganisms such as fungi, bacteria and viruses. This constitutes a major concern in the context of occupational health and safety. There are in fact different means by which the workers could be affected by the microorganisms and these are described as follows:

1. Skin contact

The microorganisms can gain entry to the human body by contact with the skin. Cuts and abrasions will generally make the worker more vulnerable to the disease causing organisms. As a result, the worker may suffer from illnesses such as infection of the skin and eyes amongst others.

2. Inhalation

Inhalation constitutes an easy means for the microorganisms to gain entry to the human body. These inhaled microorganisms are responsible for causing respiratory and gastrointestinal diseases in the workers (Bardos, Crook and Lacey 1988).

3. Hand to mouth contact

Improper washing of the hands or unwashed hands can lead to the worker being contaminated with the disease causing organism, by hand to mouth contact.

3.1.3 Chemical risks and factors

Various chemical hazards arise during each and every processes occurring at a treatment plant. The chemical encounters can have deleterious effects on the health of the workers. It is hence essential that a risk assessment of these hazards is made in order to deter any unpleasant incidents and to protect the health of the staffs. As such, the main factors that are responsible for the exposure of the workers to chemical risks are explained as follows:

1. Decay of organic material

Toxic gases are released into the atmosphere when the organic material contained in the waste water decomposes. The gases evolved include hydrogen sulphide, methane and ammonia gas. Hydrogen sulphide is lethal to the human body and when present in low concentrations it may cause headaches and conjunctivitis (Smith 1986). Methane which is also released during the decomposition of sewage is explosive (Stellman 2011) and can also cause asphyxia.

2. Use of gaseous chlorine

Gaseous chlorine is used to disinfect tertiary effluent, so as to attain more or less same pathogen concentration as that found in natural aquatic environment. (WHO n.y) As such, the workers may suffer from adult respiratory distress syndrome by inhaling the gaseous chlorine during the disinfection process. (Stellman 2011)

4 Prevention and Mitigation measures

4.1 Measures pertaining to physical risks

• Heavy boots should be used to minimize injury when handling heavy loads.
• The load should be kept as close to the body for as long as possible while lifting. The heaviest side should be near the body as this will prevent overturning possibilities.
• A stable position should be adopted when lifting. The feet should be apart with one leg slightly forward so as to maintain balance.
• The load should be held with a good grip in order to avoid slipping of the load.
• As far as possible, the load should be kept not lower than the knee height (Bansoodeb 2012).
• There should therefore be a good housekeeping practice in the wastewater treatment plant. The minimum amount of water puddles should be present on the floor. Water should be properly and constantly swept up.
• Areas where there will always be water puddles should be marked properly.
• Leaks should be fixed to prevent excessive accumulation of water on the floor.
• Flooring surfaces that provide traction should be used.
• Walking over spills should be avoided and appropriate footwear with non-slip sole should be worn by workers.
• Areas where there is the risk of water engulfment as a result of heavy rain and flooding should be surveyed.
• Proper confined space procedures should be used.
• In addition, safety of the workers can be ensured if they monitor themselves in such a way that they take all necessary precautions and abide by the rules and regulations of the wastewater treatment plant.
• Guard rails should be placed around all open water sources. Rescue equipment such as floats and hooks should be kept available near all water tanks.
• A fall protection gear should be worn and a co-worker may be present nearby for monitoring in case of mishap.
• When grates are lifted over waterways and tanks for access, the area should be cordoned off. Also, hazard warning signs should be placed.
• All moving parts of the equipment should be guarded. Warning signs should be placed near these parts.
• Since work is being carried out in a wet environment, precautions should be taken when electrical equipment is being used. Electrical cables should be checked at all times (Statefundca n.d).

4.2 Measures pertaining to microbial risks

• Workers are best protected from exposures to disease by engineering controls and work practices. However, then engineering controls are not possible, personal protective equipment should be used.
• A good hygiene should be practiced. Hands should be washed well with clean water and soap after work and before eating or smoking.
• Parts of your face should not be touched with the hands while working unless they have been washed.
• Waterproof gloves should be worn when pumps or screens are being cleaned and wastewater, sludge or grit is being handled.
• Workers should not leave the workplace with the same clothes worn while working. Clothes should be changed or decontaminated.
• Vaccination should be done to prevent any unwanted situations (Elcosh n.d).

4.3 Measures pertaining to chemical risks

• Areas where there is the risk for explosion from flammable gases should be surveyed.
• Personal protective equipment (PFE) that gives the maximum protection against toxic gases should be used. Examples of PFE can be breathing mask or oxygen cylinder.
• Ventilation should be allowed in manholes for a while prior to entering it. The reason is to remove or at least lessen the amount of toxic gases present in the confined space. Also, the manhole should be cleaned by flushing it with water before entering.
• A worker should never be entering a manhole alone. Another worker should always be present for assistance in case of mishaps.
• When working in manholes near industrial zones or hospitals, additional precautions should be taken. It should be ensured whether hot water or toxic substances goes into the manhole and if this is the case, the entering of these substances should be stopped at that particular time (Bansoodeb 2012).

5 Legislative Framework

Occupational Safety and Heatlh Act, 2005 (OSHA) caters for health and safety of employees in Mauritius and its main aim is to prevent workers from having any serious injury or health on their workplace or due to the location of their workplace.

The law ensures that employees are being provided with safe working conditions in order to prevent workers from being injured or killed at work.

It is the Occupational Safety and Health administration that sets and enforces the health and safety standards. (Online, OSHA)

5.1 Occupational Safety and Health Act 2005 (MAURITIUS)

5.1.1 Part one: Preliminary

The part one of the Act relates mainly to the application of the Act and the Standards and classification.

5.1.1.1 Application of Act

The act is applicable to the government workers, people who are bound by a contract of employment to their employers, self-employed people, and freelancer workers.

Unfortunately a condition in the act allows a Minister to bypass the act where the latter seems to find it necessary and in the interest of public security, public safety or public interest.

5.1.1.2 Standards and classification

This part of the act also unfortunately gives choice to the Minister whether the latter wants to provide any standard, method of classification or classification system which could have been used as a general guide.

The employer shall provide a standard, method of classification or classification system with which the Court would be satisfied or else he would be liable to legal actions.

5.1.2 Part two: Duties and Responsibilities

The general duties of employers, especial duties of employers, especial duty of employers making use of machinery and the preventions concerning young persons are detailed in this section of the act. This section also provide details of the duties of Health and Safety officers and also the setting up, functioning and meeting of Health and Safety committees. The other parts of the Act is similar to the OSHA of United States as briefed in section one and the only major difference is that the inspector is the Health and Safety Officer and that instead of Occupational Safety and Health administration, in Mauritius we have Occupational Safety and Health committee.

5.2 Occupational Safety and Health Act of 1970 (United States)

Workers have to be satisfied with working conditions that ensures their safety as well as welfare and hence OSHA provides workers with the right to: 1. Request for inspection for their site of work; 2. To ask for information for possible potential hazards that may occur on their site of work and also adequate training methods to prevent harm, 3. OSHA standards applicable to the site of work. 4. To ask information for any incidence that resulted in injuries of workers; The OSH act is applicable to all government workers and private sector workers but is not applicable to people who are self-employed and workplace Hazards controlled by other agency (for example, the Coast Guard). (Online, OSHA)

5.2.1 OSHA standards

The standards are rules to prevent employees from getting injured by using systematical methods that have proven their worth. In our treatment plants, workers are exposed to hazardous chemicals (chemical treatment) as well as the loud noise of the pumping system during their working time and standards enables to limit both the time a worker is exposed to hazardous chemical and also the concentration of the chemical the latter is exposed to. The standard also ensures that the injuries occurring at the site of work are carefully put in the
records and that there is monitoring of the cases that have cropped up due to the hazards by the employers.

5.2.2 Inspection of workplace

Upon a complaint is filed, and whereby OSHA is asked to inspect a workplace, an inspection needs to be carried out as soon as possible as there may be risk of injuries and the life of the workers may be at risk. On arrival of an OSHA inspector, workers or their representatives are allowed to engage in conversation with the inspector, follow the inspector while the inspection of the site is being carried out and also workers are allowed to be present in meetings between the inspector and employer whether it is before or after the inspection. After the inspection, if inspector has found proof of violation of the OSHA standards, fines or even citations may be issued to the employer from OSHA. Depending on the seriousness of the problem or potential hazard that may be caused, workers have the right to ask for the problem to be solved as soon as possible instead of waiting for the initial deadline which otherwise would depend on the willingness of the employer to fix the problem. The person filing the complaint has the right to get a copy of the results following the inspection by an inspector of OSHA of the site of work. (Online, OSHA)

5.2.3 Employer responsibilities

The main responsibility of the employer is to offer a safe working condition to the employee and is in adequacy to the OSHA standards. Instead of only relying on equipments such as gloves,masks and other type of personal protective equipment(PPE) , OSHA encourages to adopt different improved working conditons that would have reduced the risks of already occurred hazards to occur again. In our case of wastewater treatment plant, making use of safer chemicals and enclosing processes to trap harmful fumes may be ways of reducing the risks of the worker being subject to health problems due to his working conditions.

Employers have the responsibility to:

1. Provide information for possible potential hazards that may occur on their site of work via labels, alarms, chemical information sheets and also provide adequate training methods to prevent harm
2. Have records for any incidence that resulted in injuries of workers
3. Carry out tests on the site of workers, such as air sampling required by some OSHA standards.
4. Provide a notice board, poster or any other means to post OSHA citations and other information related possible on site injuries.
5. Inform OSHA within 8 hours of a workplace incident in which more than two workers has been injured or if any serious injuries occurred.

5.3 Environmental Impact Assessment (EIA)

The set-up of a wastewater treatment plant has a very significant impact on the physical landscape, environmental and also on social issues. It entails both positives and negatives and thus, to ensure proper planning and forecast of these issues, an Environmental Impact Assessment is usually undertaken prior to the establishment of a plant.

It evaluates the expected effects on the natural environment, human health, social and on property. As a matter of fact, the study requires a multi-disciplinary approach which is most capable of generating the most precise data enabling sound decision making. It is also an integral part of sustainable development. As a matter of fact, Mauritius originally adopted formal procedures for EIA in June 2013 after the subsequent amendment of the Environmental Protection Act (EPA) 1991. Moreover, a new Environment Protection Act has been brought about as from 5 September 2002 to lay further emphasis and to improve the instutional and legal framework for the protection of the environmental assets of Mauritius and to cater for sustainable development. The recent act allows for greater transparency and also depicts the contents of the EIA among others (Ministry of Environment & Sustainable Development, n.d.)

6 Recommendations

In order to reduce the risks of encountering hazards at the treatment plant and hence increase safety of the personnel, the following measures may be undertaken: ‘ A risk assessment of all the activities occurring at the plant could be carried out so as to develop strategies accordingly, thereby minimising the risks.

• The wastewater treatment plant could be upgraded such that the working space is increased. In this context, it is necessary to first obtain sufficient funds to carry out the construction works.
• The workers at a treatment plant are required to carry out repetitive tasks. Coupled with this, the use of certain equipment entail bad working postures which can potentially jeopardize the health of the workers. As such, a solution to this problem could be the construction of new ergonomic treatment plants.
• The authorities should disseminate knowledge and appropriate information to the personnel so that the latter can adopt safe working practices pertaining to the operation, control and monitoring of the system during each and every stage involved in the treatment process.
• Rules and regulations, pertaining to safe practices, should be set up. Also, competent people should be employed and assigned the task of reinforcing these rules and regulations.
• Frequent maintenance and repair of the machinery utilised at the treatment plant could be carried out. This would deter serious accidents from occurring or at least reduce their incidence. For example, it must be ensured that the guard rails are well secured to their bases.
• Innovative technologies should be employed during the treatment of wastewaters. For instance, the use of technology to ensure adequate ventilation in the confined spaces would eliminate the health problems linked to oxygen deprivation.
• Sufficient lighting should be provided while the personnel are at work. This would serve as an effective tool to avoid any mishaps such as walking over water puddles.

7 Conclusion

The purpose of wastewater treatment plant is to treat wastewater to remove numerous pollutants and make the water appropriate to be discharged to the environment. The sources of wastewater can be:

• Domestic or municipal
• Industrial
• Infiltration and inflow
• Storm water.

The treated water coming out from the wastewater treatment plant is called the effluent. Thus, the harmful effects that these substances could have caused to the environment are minimised. However, it is obvious that in wastewater treatment plants, risks and hazards are involved. From this assignment, we were able to have a better understanding of the risks and hazards that the workers are exposed to in the wastewater treatment plant. As such, it has been seen that it is important to inculcate a culture of occupational health and safety among the workers. In addition, a number of Health and Safety laws and measures have been adopted in many countries and also Mauritius by the Ministry of Environment and Sustainable Development so as to minimise unfortunate events in wastewater treatment plants.