Previous studies for removal of ammonium from wastewater were mainly conducted using biochars produced from agricultural residue. Feedstock type (agricultural residue, wood, animal waste, and aquatic waste), as well as pyrolysis temperature, can significantly influence biochar properties and hence its adsorption capacity. Such studies are useful in decision making for selecting biochar depending on feedstock availability and pyrolysis temperature. This study aims to explore the effects of different types of biochar (laboratory prepared novel water hyacinth and algae biochar, conventional cedar wood, rice straw, and pig manure biochar) on the adsorption kinetics for ammonium removal from wastewater. The adsorption kinetics of biochars were compared to that of commercially available clinoptilolite and interpreted with their respective physicochemical properties (SEM, FTIR, XRD). Batch tests were performed to evaluate the effects of biochars on adsorption of ammonium nitrogen at different concentrations (10 mg/L and 100 mg/L). The tests reveal that clinoptilolite has the highest adsorption capacity. Among biochars, pig manure (animal based) biochar has a higher adsorption capacity in comparison to conventional agricultural residues based biochars. The capacity of pig manure biochar under highly concentrated ammonium solution (100 mg/L) is merely 20% lower than that of clinoptilolite. Both water hyacinth and algae biochar produced at higher temperature (600 °C) show higher sorption rate and capacity (depending on the initial concentration of ammonium) for ammonium in comparison to that produced at a lower temperature (300 °C). This is likely due to an increase in porosity at higher temperatures of pyrolysis.

Stormwater quality is well known for its highly stochastic nature and not necessarily well explained by mechanistic urban build up and wash off models. Therefore, local empirical data (based on land use) are an essential compliment to statistical analyses of global data. This paper reports on a large-scale monitoring of the 12 key water quality parameters of suspended solids, nutrients, and heavy metals for stormwater runoff in urban discharges from nine urban land uses with varying sizes in Singapore. It was found that, in general, the average of the event mean concentrations for total nitrogen, total phosphorus, total organic carbon, total suspended solids (TSS), and phosphate in parkland land use were higher than the other eight studied land uses. Based on Pearson’s correlation analysis, significant correlation between pairs of water quality parameters was observed. Particularly, there was significant correlation between TSS and most of the other tested water quality parameters in all land uses. A pollutant data set from this study will assist in developing appropriate stormwater quality models, guide the establishment of stormwater treatment objectives and preliminary designs for Singapore catchments, as well as provide an essential complement to statistical analyses of global data for stormwater characteristics.

To better evaluate and enhance the performance and benefit of sustainable stormwater management (SSWM) in developing countries, this study proposes a comprehensive evaluation framework based on thorough literature review. This framework re-classifies evaluation goals and indicators into four aspects—stormwater system, integrated management, social engagement, and urban development. The purpose of this review is to provide a guideline for decision makers to choose appropriate goals and indicators according to different regional context. Meanwhile, a structured procedure for comprehensive evaluation of SSWM is proposed to guide a well-organised decision-making process. Furthermore, pros and cons of eight decision support tools, as well as their functional focus, are compared, aiming to provide references for SSWM in developing countries. Outcomes presented in this review are expected to support decision makers in the process of screening optimal SSWM strategies and monitoring SSWM projects.

Ammonia nitrogen, which consists of ammonium and free ammonia, is one of the key parameters to evaluate the water quality and it is an important analyte in the biotechnology and agriculture. However, ammonia nitrogen exists mainly as ammonium in most waters as the pH is below 9. In this work, we propose a tilted fiber Bragg grating (TFBG) sensor that is surface-functionalized with a thin film of polyvinylidene fluoride bromophenol blue (PVDF-BPB) for ammonium detection in wastewater. The surface structure of the PVDF-BPB film was modified by reacting with ammonium, resulting in a correlative modification of extinction ratio of TFBG cladding modes. The reaction strength between the ammonium and the bromophenol blue was proportional to the concentration of ammonium. By calculating the integral area of all cladding modes versus reaction time, the concentration of ammonium can be precisely quantified. Experimental results showed that the proposed sensor could provide a linear response of ammonium detection over a concentration range of 0.1 × 10 mg/L within 5 minutes. Finally, we demonstrate the feasibility of the proposed sensor for measurement of ammonium in wastewater, using our probe gave results comparable to a commercial ammonium probe.