**2. Theories on sustainable SWM, waste separation and the 3 R's principles**

The purpose of sustainability in SWC is to give good services for humans and protecting the environments [15]. It is a theory regarding the stability of economic, social and environmental features. According to Van de Klundert and Anschütz [16], sustainable SWM contains a system that can keep itself for longer periods without decreasing the resources.

In defining sustainable SWM, financial, social and environmental issues are essential elements.

The idea involves that environmental sustainability needs SWC and disposal that impose an unlimited load on the environment to be considered as resources which could be transformed in a closed-cycle system by restoring numerous natural cycles that in turn leads to a smaller loss of raw materials, energy and nutrients.

The application of waste separation and the 3R's principles in SWM practices depends on some considerations. Waste reduction is associated with the knowledge of waste generators reuse and recycling. Essentially, recycling behaviours have a direct link with three sets of variables. Firstly, according to Vining and Ebreo [17], with environmental values form underlying attitudes towards the environment. In such attitude, people are more likely to act in environmentally suitable behaviours. Secondly, with situational aspects which hold facilitating and spiking impacts and are usually categorised as contextual [18, 19], socio-demographic [20], knowledgecentred [21] and experience-centred [22]. Thirdly, with psychological aspects that are distinctive perceptual characters of the individual and contain altruistic drives to reuse [23], outcome beliefs [23], subjective norms (or social influence; Chan [24]). Other related issues are a set of logistical factors and personal efficacy variables, such as time to undertake the activity [25] and belief that individuals have a responsibility to protect their environment which is termed as environmental 'citizenship' beliefs [26].

The core significance of recycling, composting and other commodity-based actions is the decrease in the quantity that wants to be moved to dump areas. In various countries, still there is a vast difference between the reality in the ground and the principle. From an environmental viewpoint, recycling may be favoured, but the economic costs or the problems of the institutional may inhibit waste recycling implementation in integrated SWM. The real integration can occur at numerous stages, Van der Klundert and Lardinois [27]. This contains waste processors such as formal and informal recyclers; waste generators such as households, industry and agriculture; and government organisations such as waste managers and urban planners. By collaborating with the societies, micro-enterprises may play a great role in public environment education. Having strong relation with the inhabitants can offer chances to introduce separation at sources. This could help workers benefit from collecting and selling the recyclable materials and create an opportunity for cost reduction for the municipality by reducing the quantity of waste.
