Entrepreneurship and Sustainability Issues is a peer-reviewed journal which publishes original research papers and case studies

Approximately 1,000 tonnes of solid waste are generated in Semarang every day, only 850 tonnes of which are transferred to the Jatibarang Landfill. Solid waste that is not transferred to the landfill can trigger environmental and health problems. With the help of community groups, reduction of solid waste is achievable using ‘the three Rs’ of waste reduction and the implementation of waste banks. Waste banks could act as mediums for depositing waste, improve the socio-economic status of local residents, and develop community connections. Waste banks improve the volume of waste reduction and reduce landfilled waste, helping to extend the operational life of landfills. This study examined the role of waste banks in Semarang and the potential to improve waste management based on the sampling of solid waste generation and composition. This topic was investigated with a purposive sampling method. Results showed that the existing system of waste banks in Semarang is ineffective in reducing waste. However, the system could be improved by increasing waste bank usage, including for various types of valuable waste in Semarang.

An investigation on the use of landfill bioreactors was conducted to elaborate an alternative solution on the municipal solid waste management in Jatibarang Landfill, Semarang. In addition, this study is also trying to develop a prevention on leachate and greenhouse gases pollution which are potentially emits from a landfilling process. There are six landfill bioreactors that were constructed for this study, which consist of two anaerobic bioreactors (R1 and R2) and two aerobic bioreactors (R3 and R4). Leachate recirculation was applied on R1 and R2 since the leachate production began while R3 and R4 was given air injection with 2 l/min flow rate. R1 and R2 maintained its thermophilic phase longer and generated more methane gases than aerobic bioreactors. Meanwhile, both aerobic bioreactors reached the thermophilic phase on day-7, faster than the anaerobic bioreactors.

In some areas, compacted clay liner is chosen as leachate barrier for solid waste landfill. Due to the typical shape of the landfill, the compacted clay liner will be rested both in flat and sloping ground. Since clay has characteristics of low shear strength, improvement of shear stability of compacted clay liner is required. One of the stability methods to increase the shear strength of clay is by adding another material which has higher shear stability. In this study, bentonite is used to represent clay liner while zeolite is utilized as stabilizer material. Four compositions of bentonite with 0%, 5%, 10%, 15% addition of zeolite were prepared to investigate the stability performance of the mixtures. The results indicate that the addition of zeolite into bentonite has increased the friction angle of the bentonite. However, the addition of zeolite seems to alter the hydraulic performance of bentonite. The highest permeability is demonstrated by the bentonite with 15% of zeolite. Whether the permeability increases, the hydraulic performance of all the mixtures are still met the maximum permeability allowed for landfill liner.

Currently, the presence of laboratories has become a difficult thing to be separated from the learning system in the university. Moreover, there are many universities that have begun to encourage their students and lecturers to do researches more frequent, for needs both of lecture activities and theses. These conditions trigger the laboratory management to improve their service quality, such as through improvement of the comfortability. From this improvement, it is expected to increase the productivity of people who are doing their activities in a laboratory. However, while the working productivity is being prioritized, there is a problem that is often forgotten, namely health and safety environment. An unhealthy working environment has the possibility to cause stress to people who are working in it. Hazard potentials that exist in a laboratory are caused by the use of reagents and research equipment. To prevent the occurrence of these hazard potentials, deep understanding of risks potential in a laboratory is needed. Based on a research at XYZ Laboratory, a risk analysis and risk assessment are needed to be done by a laboratory, which is often used by students and lecturers in a university, with the purpose of determine the severity and likelihood level of an incident happened. Furthermore, AS/NZS 4360-2004 method, which is used in this research, is also a method to determine the priority of how handle a risk and what is the best step to prevent it.

Currently, Diponegoro University has been composting dry leaves with conventional methods through a facility called TPST. Even so, the processing which have been carried out has not been able to process all the organic waste in the location. Seeing these conditions, it is necessary to look for alternatives that are better and more economical to apply. Bioactivators are used from the leaves ofPterocarpus indicuswhich serve to accelerate the composting process. The bioactivators was made by making a solution of the leaves of Pterocarpus indicus which has been mashed, then mixed with molasses and rice flour and then left for 15 days. By using experimental method, the composting process is observed. This study aims to analyze the quality of compost with applicable standards. The quality of compost is assessed by looking at the pH, temperature, and macro nutrient percentage such as C-organic, N-total, and C / N ratio. During the composting process, variations in the stirring frequency are carried out, which is once every 2 days, 4 days and 7 days. After doing laboratory test, not all reactors meet the standards for pH, temperature, C-organic, N-total, and C / N ratio according to SNI 19-7030-2004.