WASTE MANAGEMENT- Saving the earth

 WASTE MANAGEMENT

Waste management can be defined as all the activities that are required to manage waste from the point of collecting the waste to recycling and monitoring. Waste in waste management refers to unwanted or unusable material that is produced through the activity of humans and can have different forms.

The process of waste management involves treating solid and liquid waste. During the treatment, it also offers a variety of solutions for recycling items that aren’t categorized as trash.

                     

LIQUIID WASTE MANAGEMENT

Dealing with liquid wastes is one of the biggest challenges of urban sanitation. Liquid waste management requires capital investment, skilled personnel, coordination between different government departments and organisations, and awareness of the issues by the public. Failure to manage liquid wastes, especially human excreta, leads to health and environmental problems.

Faecal sludge management

When human excreta collects in a pit latrine, the solids settle at the bottom and form a slurry called faecal sludge. Over time the sludge accumulates and periodically needs to be removed and disposed of. This process presents several challenges because the sludge is offensive, a potential danger to human health and highly polluting if dumped indiscriminately into the environment. Faecal sludge management (FSM) is a set of processes designed to ensure that people and the environment are protected from these hazards. It includes the storage, collection, transport, treatment and safe end use or disposal of faecal sludge .

Pit emptying

The process of pit emptying is sometimes called desludging. There are manual and mechanical methods for desludging, but the manual removal of faecal sludge from pit latrines poses severe risks to those undertaking the task.

Vacuum trucks

Vacuum trucks are vehicles equipped with a storage tank and pump with a hose that is lowered into the pit to suck the sludge up and out into the storage tank . The sludge can then be easily transported to a suitable disposal site.

Hand-operated pumps

The Sludge Gulper, like the one shown in FIG is an example of a smaller hand-operated pump. These can be taken to pit latrines that are inaccessible to larger pumps. It is a simple design consisting of a PVC pipe containing two valves and can be built using locally available materials.

Disposal of the sludge

Several options are available for disposal of the collected sludge (Pickford and Shaw, 2005). It can be put directly onto land and used as a soil conditioner, but this is only possible if it has been left untouched for at least two years (Brikke and Bredero, 2003). Fresh, untreated wet sludge poses high risks for human health and so should not be put on land used to grow crops.

Septic tanks

A septic tank (Figure 6.5) is an underground and watertight tank made of concrete, fibreglass or PVC in which sewage is collected and partially treated. These are used for water-flushed systems that are not connected to a sewer. Concrete septic tanks are commonly used in Ethiopia.

Wastewater enters the tank, remains there for a time, and is displaced out of the tank by new wastewater coming in. There are no pumps or mechanical parts. The time the wastewater remains in the tank is called the retention time and should be a minimum of 24 hours. In this period, the solid matter in the sewage settles to the bottom of the tank, where it is partially degraded by anaerobic micro-organisms.

Sewage sludge

Sewage sludge treatment describes the processes used to manage and dispose of sewage sludge produced during sewage treatment. Sludge treatment is focused on reducing sludge weight and volume to reduce transportation and disposal costs, and on reducing potential health risks of disposal options. Water removal is the primary means of weight and volume reduction, while pathogen destruction is frequently accomplished through heating during thermophilic digestion, composting, or incineration.