Statistically-Based Comparison of the Removal Efficiencies and Resilience Capacities between Conventional and Natural Wastewater Treatment Systems: A Peak Load Scenario

Abstract

Emerging global threats, such as climate change, urbanization and water depletion, are driving forces for finding a feasible substitute for low cost-effective conventional activated sludge (AS) technology. On the other hand, given their low cost and easy operation, nature-based systems such as constructed wetlands (CWs) and waste stabilization ponds (WSPs) appear to be viable options. To examine these systems, a 210-day experiment with 31 days of peak load scenario was performed. Particularly, we conducted a deliberate strategy of experimentation, which includes applying a preliminary study, preliminary models, hypothetical tests and power analysis to compare their removal efficiencies and resilience capacities. In contrast to comparable high removal efficiencies of organic matter-around 90%-both natural systems showed moderate nutrient removal efficiencies, which inferred the necessity for further treatment to ensure their compliance with environmental standards. During the peak period, the pond treatment systems appeared to be the most robust as they indicated a higher strength to withstanding the organic matter and nitrogen shock load and were able to recover within a short period. However, high demand of land-2.5 times larger than that of AS-is a major concern of the applicability of WSPs despite their lower operation and maintenance (O&M) costs. It is also worth noting that initial efforts on systematic experimentation appeared to have an essential impact on ensuring statistically and practically meaningful results in this comparison study.

Model-Based Analysis of Increased Loads on the Performance of Activated Sludge and Waste Stabilization Ponds

“…These configurations were chosen because of their basic, conventional, and common settings for removing organic matters and nutrients. The overview of the experimental setup of two treatment systems is illustrated in Figure S1 (Supplementary Material A) and its detailed description can be found in Ho, Van Echelpoel, Charalambous, Gordillo, Thas and Goethals [3]. To ensure the stability of the systems, their start-up period was maintained for 179 days, with samples being collected and analyzed two times per week.…”

“…Until now, the practicability and feasibility of this alternative is mostly evaluated by system-specific data collection from different sources. These subjective comparisons resulted in relative general conclusions [3]. More importantly, a key criterion of these systems was missing, namely their resilience capacity to disruptions, which indicates the ability to adapt, endure, and recover from changing conditions [4,5].…”

Research hotspots and current challenges of lakes and reservoirs: a bibliometric analysis

“…In fact, it is difficult to overstress the assets of the two natural systems for wastewater treatment, i.e. high removal efficiency, simplicity, and low cost, especially when affordability remains a bottleneck for clean water and sanitation in developing countries (Ho et al 2018). These inland waterbodies can provide a high capacity of self-purification thanks to high complexity with an interconnected web of biochemical reactions and complex hydraulic processes, thereby resulting in their massive use (Ho et al 2017).…”

A Practical Protocol for the Experimental Design of Comparative Studies on Water Treatment

“…In particular, we wanted to evaluate and compare the removal efficiency and resilience capacity of the two systems in a shock load scenario with three phases: (1) initial phase; (2) high-strength-wastewater phase; (3) recovery phase, via two indicators, i.e., COD and TN. The overview of the experimental setup of two treatment systems is illustrated in Figure A1 (Supplementary Material A) and its detailed description can be found in Ho et al [26].…”