Municipal solid waste management in South Africa: from waste to energy recovery through waste-to-energy technologies in Johannesburg

ABSTRACT

“Waste-to-energy” (WTE) technologies have been presented as one of the avenues to improve the management of solid waste whilst promoting clean and healthy urban environments through the recovery of waste and generation of energy. Research suggests that with the right investment in technologies and institutional changes, waste can potentially become a resource that can contribute to the socio-economic development of cities. It is in this context that this paper presents a review of the literature on WTE technologies and their implications on sustainable waste management in urban areas. The paper particularly contributes to our understanding of WTE technologies and its potential on Municipal Solid Waste Management (MSWM) in Johannesburg, South Africa. It is estimated that the city of Johannesburg’s landfills airspace will be completely depleted by year 2023. This projection becomes a motivation for the identification of suitable WTE alternative avenues to manage waste in the city. The paper argues that WTE technologies can contribute significantly to sustainable waste management, economic growth, ecological and environmental well-being.     

Shaped by race: why “race” still matters in the challenges facing biodiversity conservation in Africa

This article uses experiences from South Africa to argue that, despite progress made in making biodiversity conservation compatible with social, political and economic changes, progress could still be limited by reluctance of social actors to acknowledge and engage with the issue of race. The article argues that acknowledging the history of conservation in Africa, including close ties to racially charged colonialism, could be a positive impetus in the transformation of conservation to make it more socially, economically and politically justifiable.     

The Belt and Road Initiative and the 2030 Agenda for Sustainable Development: seeking linkages for global environmental governance

ABSTRACT

Global environmental cooperation serves as an important part in the Chinese ideal of building a Community with a Shared Future for all Human Beings. The report of 19th CPC National Congress indicates that China is committed to proactive mitigation under the Paris Agreement and further participating in global environmental governance under the 2030 Agenda for Sustainable Development, and both of which are largely integrated to the Belt and Road Initiative (BRI). BRI are also closely linked with South–South environmental and climate cooperation proposed by China from previous UN summits. Based on shared ideas, intersected agendas, and compatible governance approaches, BRI and the 2030 Agenda for Sustainable Development grow increasingly relevant and they might form synergies based on increasingly interactive relations. In sum, seeking and intensifying the linkages between BRI and 2030 sustainable development goals (SDGs) could address global environmental governance deficits and enhance cooperation among nations.     

Use and users of municipal commonage around three small towns in the Eastern Cape, South Africa

Municipal commonages surround many small towns throughout South Africa, and are an integral component of the national land reform programme. But little is known about their extent, use or value, and most appear to have limited or no management or investment. This paper reports on a survey of randomly selected households in three small towns in the Eastern Cape to ascertain the extent and purpose of use of municipal commonages. Between 27% and 70% of urban households used commonage depending on site. Key resources used were fuelwood, medicinal plants, and grazing of livestock. Typically, commonage using households were poorer and less educated than other urban residents, although the profile of users is unique for each town. Given the extensive use of commonage resources, and their contribution to the livelihoods of the poor, local municipalities need to develop and implement sound management strategies that account for all users of commonages, rather than the oft encountered focus on livestock owners and production.     

Anomalous Ba/Ca signals associated with low temperature stresses in Porites corals from Daya Bay, northern South China Sea

Barium to calcium (Ba/Ca) ratio in corals has been considered as a useful geochemical proxy for upwelling, river flood and other oceanic processes. However, recent studies indicated that additional environmental or biological factors can influence the incorporation of Ba into coral skeletons. In this study, Ba/Ca ratios of two Porites corals collected from Daya Bay, northern South China Sea were analyzed. Ba/Ca signals in the two corals were ‘anomalous’ in comparison with Ba behaviors seen in other near-shore corals influenced by upwelling or riverine runoff. Our Ba/Ca profiles displayed similar and remarkable patterns characterized by low and randomly fluctuating background signals periodically interrupted by sharp and large synchronous peaks, clearly indicating an environmental forcing. Further analysis indicated that the Ba/Ca profiles were not correlated with previously claimed environmental factors such as precipitation, coastal upwelling, anthropogenic activities or phytoplankton blooms in other areas. The maxima of Ba/Ca appeared to occur in the period of Sr/Ca maxima, coinciding with the winter minimum temperatures, which suggests that the anomalous high Ba/Ca signals were related to winter-time low sea surface temperature. We speculated that the Ba/Ca peaks in corals of the Daya Bay were most likely the results of enrichment of Ba-rich particles in their skeletons when coral polyps retracted under the stresses of anomalous winter low temperatures. In this case, Ba/Ca ratio in relatively high-latitude corals can be a potential proxy for tracing the low temperature stress.     

ENVIRONMENTAL AUDITING: Which Birds Are Useful Bioindicators of Mining and Grazing Impacts in Arid South Australia?

Significant annual variations in population size of most species were evident with greater abundance of most species in wet years. Habitat variables, particularly vegetation structure, were also an important determinant of the abundance of most bird species and tended to mask the impacts of the land use under investigation. Several bird species had benefited from the provision of permanent water at mining and pastoral sites. Other species utilized increased nesting or feeding opportunities associated with the mining operation and increased food supply at the pastoral sites. Crested bellbirds and mixed-feeding flocks of small insectivorous birds were apparently disadvantaged by mining and hence may be useful bioindicators of mining impacts. No bird species or community parameters were identified which could serve as useful early warning bioindicators of pastoral impacts.     

华南东部主要铀矿区居民室内外氡浓度研究

对华南东部6个铀矿区居民室内外空气氡浓度及其变化规律进行了研究。矿区废渣和坑道口释放出来的氡气对周围大气形成了氡污染,特别是在矿区周围0.5～1.5 km的范围内的污染严重。但是空气中的这种氡污染随离矿区的距离增大而迅速减弱。矿区周围居民室内氡的浓度高,是广东省室内氡浓度平均值的10倍左右。在进行调查的190个居室中,有45个(23%)居室室内氡浓度超过美国环境保护局制定的148 Bq/m3室内氡浓度的上限值。居室中氡浓度的升高,除了受矿区释放出来的氡污染外,更主要是因本地区属高本底辐射区,房基下的土壤、岩石和建筑材料中的铀、镭等放射性元素的含量高,其放射性衰变产生的氡释放出来进入室内。      

南海重点海洋倾倒区表层沉积物富集特征及其潜在生态风险评价

根据2005南海三个重点海洋倾倒区,即九澳岛重点海洋倾倒区、黄茅岛重点海洋倾倒区、汕头重点海洋倾倒区的监测,分析其表层沉积物重金属的监测资料,采用富集系数法和Hakanson潜在生态危害系数法对其富集度和潜在生态危害程度进行了分析和评价.结果表明:在三个倾倒区表层沉积物所监测的重金属中,Cu和Pb元素的富集度相对最高,Hg和Cd元素的富集度较低,从空间上看,潜在生态危害系数评价结果显示,南海三个重点海洋倾倒区表层沉积物中的重金属对海洋生态系统的潜在生态危害非常轻微,均属于轻微潜在生态危害范畴,其中轻微潜在生态危害程度相对较重的是Cd和Hg元素,Cu和Pb元素的轻微生态危害程度较轻.     

南中国海地区红树林的利用和保护

南中国海具有丰富的浅海和热带的生物多样性,是全球红树林分布的中心之一.南中国海地区红树林面积大约占全球的28%,该区红树植物的多样性为世界最高,共有46种真红树分布于此.由于受人口增加和经济发展的巨大压力,南中国地区红树林资源破坏严重,退化趋势明显.虽然南中国海周边国家过去都实施了相应的海洋环境保护行动计划,然而缺乏区域协调措施大大降低了这些行动的有效性.本文在对南中国海地区红树林资源的利用现状和退化原因进行分析的基础上,提出南中国海地区红树林资源保护与管理的建议,以期能在双边或区域的层面上共同协作,采取适当的措施去扭转南中国海地区红树林生境退化趋势.     

南海水域不同深度非光合微生物的固碳潜能及其对不同电子供体的响应

通过对南海水域多个区域不同深度的海水分别以H2、Na2S2O3、Na NO2为电子供体经过一定时间的驯化培养后,测定其中非光合微生物的固碳潜力,并统计南海水域不同深度非光合微生物在不同电子供体条件下固碳潜力的差异性,最后结合不同深度海水的主要固碳基因丰度差异,分析南海水域不同深度海洋非光合微生物在不同电子供体条件下固碳潜能差异的原因.结果发现以Na NO2为电子供体时,海洋非光合微生物固碳能力普遍较低,各深度之间没有显著差异;以H2为电子供体时,表层海水中的非光合微生物的固碳潜力显著高于深层海水中的;而以Na2S2O3为电子供体时,深层海水中的非光合微生物的固碳潜力显著高于表层海水中的.基因分析结果表明,固碳基因cbb L在表层海水中的丰度高于深层海水,而cbb M基因在深层海水中的丰度高于表层海水.硫细菌大多以拥有cbb M基因为主,而氢细菌大多以拥有cbb L基因为主.因此不同海洋深度非光合微生物对不同电子供体响应的差异性可能和优势菌群结构的差异有关.海洋表层和深层溶解氧、无机碳含量的差异是导致菌群结构差异,乃至固碳潜力差异的重要原因.