In the past few years, one of the major changes in urban development strategies of the first-tier cities in China is the increasing focus on urban regeneration. To cope with the magnitude of migration and challenges of economic transition, these cities are forced to find new models of urban redevelopment. This has brought up a few challenging questions: How to deal with the ‘old’ typologies of urban neighborhoods, including not only their ‘outdated’ physical environment, but also new lives embedded in the dynamics of emerging social structure and productivity? How to balance interests related to big redevelopment plans of city re-branding and the thriving small businesses bound to the low cost living and working environment in the old neighborhoods? This paper will use Guangzhou as the study case, focusing on two neighborhoods: Kecun, an area with old danwei housing and factories and Lijiao village, an urban village with historical heritages, both of which are accommodating migrants and various types of small businesses. These two neighborhoods are adjacent to the southern section of the new central axis of Guangzhou, which, from the planning perspective, represents the future of the city. As planned, the southern section of the new axis will be extended in the coming years, focusing on an administrative center and multi-functional community for cultural, leisure and public activities. It is bringing large-scale urban regeneration into the adjacent areas, where migrants and small businesses are finding their ways to thrive at the moment. This paper intends to unfold the current socio-economic and spatial transformation happening in the two chosen neighborhoods, especially the role of low-cost living and working environment in enhancing social resilience and economic transition in the local scale. By doing so, the paper will indicate possible ways of creating synergies between the ‘big plans’ and neighborhood-based development. @en

Biological activated carbon (BAC) filtration is usually considered to be able to decrease formation potentials (FPs) of disinfection by-products (DBPs) in drinking water treatment plant (DWTP). However, BAC filters with long running time may release microbial metabolites to effluents and therefore increase FPs of nitrogenous DBPs with high toxicity. To verify this hypothesis, this study continuously tracked BAC filters in a DWTP for one year, and assessed effects of old (running time 8–9 years) and new (running time 0–13 months) BAC filters on FPs of 15 regulated and unregulated DBPs. Results revealed that dissolved organic carbon (DOC) removal was slightly higher in the new BAC than the old one. All fluorescent components of dissolved organic matter evidently declined after new BAC filtration, but fulvic acid-like and soluble microbial product-like substances increased after old BAC filtration, which could be caused by microbial leakage. Correspondingly, new BAC filter generally removed more DBP FPs than the old one. 46.5% HAA7 FPs from chlorination and 44.3% THM4 FPs from chloramination were removed by new BAC filter. However, some DBP FPs, especially HAN FPs, were poorly removed or even increased by the old BAC filter. Proteobacteria could be a main contributor for DBP precursor removal in BAC filters. Herminiimonas, most abundant genera in new BAC filter, may explain its better DOC and UV254 removal performance and lower DBP FPs, while Bradyrhizobium, most abundant genera in old BAC filter, might produce more extracellular polymeric substances and therefore increased N-DBP FPs in old BAC effluent. This study provided insight into variations of DBP FPs and microbial communities in the new and old BAC filters, and will be helpful for the optimization of DWTP design and operation for public health.@en