We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Effects of typical sludge treatment on microplastics in China—Characteristics, abundance and micro-morphological evidence
AI summary Read the abstract
Different sludge treatment technologies used in China including anaerobic digestion, thermal drying, and composting were compared for their effects on microplastic characteristics and abundance, with results showing that treatment method significantly altered microplastic morphology but did not eliminate contamination. The study informs decisions about which treatment approaches best reduce microplastic transfer to soils when sludge is land-applied.
Microplastics (MPs) are emerging pollutants that are enriched in sludge. They enter soil through sludge soil amendment, landfill, and discard, which will cause inescapable environmental pollution risks. Sludge treatment technology commonly used in China include anaerobic digestion (AD), thermal drying (TD), thermal hydrolysis (TH) and aerobic composting (AC). In this study, characteristics of MPs in sewage sludge from four representative large cities in China (Zhengzhou, Chongqing, Guangzhou, and Guilin) were analyzed. Effects of four representative sludge treatment technology on sludge MPs were also studied. In addition, the amount of MPs input to soil from sludge in China was estimated. The abundance range of sludge MPs of representative cities in China was 1448-11,125 n∙kg DW. Previous studies indicate that this abundance range is low among other domestic cities and is close to that of European countries. MPs were predominantly fiber-shaped, accounting for 46.66%; 56.5% MPs were white and transparent, and 62.5% were polypropylene and polyethylene. The abundance of MPs in the sludge increased after TH, indicating that MPs broke into smaller particles. However, the other three treatment methods had no significant influence on the abundance of MPs. Scanning electron microscopy analysis showed that the micro-morphology of sludge MPs surface were rougher after AD, and MPs cracked following TD and TH. Furthermore, broken edges were more blurred after TH, and surfaces of MPs were damaged and eroded after AC. The input quantities of MPs in sludge to soil was deduced to be 10 particles per year. These results are important for controlling the potential risk of sludge MPs in China.
More Papers Like This
The Pollution Characteristics and Fate of Microplastics in Typical Wastewater Treatment Systems in Northern China
AI summary Read the abstract
Researchers analyzed microplastic contamination at two wastewater treatment plants in Zhengzhou, China, finding overall removal efficiencies of about 93 and 96 percent respectively. Fibers and fragments were the most common microplastic shapes detected, with much of the removed material ending up concentrated in sewage sludge. The study raises concerns that while treatment processes are effective at reducing waterborne microplastics, the contaminated sludge may redistribute the pollution when applied to agricultural land.
Configuration-driven microplastic fate in full-scale sewage sludge treatment and opportunities for system-level mitigation
AI summary Read the abstract
Researchers examined how different treatment configurations in wastewater plants shape the types and concentrations of microplastics that end up in sewage sludge — the solid byproduct that is frequently spread on agricultural land as fertilizer. Microplastic concentrations in final sludge ranged from 617 to 936 particles per gram of dry solids, with fine fragments under 100 micrometers dominating, and the specific sequence of thickening, digestion, and dewatering steps significantly influenced which polymer types were retained. Since sludge application is a major route for microplastics to enter farmland, optimizing treatment processes could meaningfully reduce environmental contamination.
Fate of microplastics in sewage sludge and in agricultural soils
AI summary Read the abstract
Researchers reviewed how microplastics accumulate in sewage sludge at wastewater treatment plants and then spread into agricultural soils when that sludge is applied as fertilizer, finding that sludge treatment processes can alter microplastic size and shape but do not eliminate them. The review calls for standardized methods to study how different sludge treatments affect microplastic properties and their downstream risks to soil health.
Sludge drying and dewatering processes influence the abundance and characteristics of microplastics in wastewater treatment plants
AI summary Read the abstract
Researchers evaluated how sludge drying and dewatering processes affect microplastic abundance and characteristics at two wastewater treatment plants in Morocco, collecting samples across multiple treatment stages. The study identified specific sludge processing steps that concentrate or transform microplastics, with implications for managing microplastic emissions when treated sludge is land-applied.
Distribution and removal mechanism of microplastics in urban wastewater plants systems via different processes
AI summary Read the abstract
Researchers compared the microplastic removal efficiency of three wastewater treatment technologies and found that the anaerobic-anoxic-oxic process achieved the highest removal rate at 83.9%. Most microplastics were transferred to sludge during primary and secondary treatment stages, with dehydrated sludge containing significant concentrations. The study highlights that while wastewater treatment plants effectively intercept most microplastics, they also redistribute contamination to sludge, which may become a secondary pollution source.
Research digests by email
When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.