Characteristics of rural agritainment sewage in Sichuan, China.

As a new form of rural tourism, agritainment originating from Sichuan food and recreation establishments is now popular all over China. The physico-chemical characteristics of agritainment sewage in Sichuan were surveyed through questionnaires and sample analysis. It was found that 5.3% of agritainment sites discharged black water directly while 25.3% of sites discharged grey water directly in the environment. The annual average ratio of sewage discharge volume to agritainment operating income is 9.24 L/yuan and could be used to predict discharge volume. The annual discharge volume from agritainment in Sichuan was 124 billion litres in 2017 and was 55% higher than that of 2016. The annual sewage discharge volume from agritainment sites in Sichuan ranged from 12 thousand to 38 million litres and the total sewage discharge volume from 24% of agritainment sites represented 77% of the total annual discharge volume. The main pollutants in Sichuan agritainment sewage were total suspended solids (10-2,470 mg/L), total phosphorus (0.07-17.1 mg/L), chemical oxygen demand (144-2,580 mg/L) and anionic surfactant (3.5-411 mg/L) and the percentage of sewage exceeding the standard (Chinese standards GB8918-1996 Class II) of these environmental indicators was up to 45%, 75%, 95% and 80%, respectively. Considering the increasing volume and concentration of agritainment sewage, we urge the public and government to be aware of related water pollution issues. Based on this study, additional surveys of characteristics of agritainment sewage are suggested to be included in the third national pollution source survey in China (2027).

Avocado seed starch utilized in eco-friendly, UV-blocking, and high-barrier polylactic acid (PLA) biocomposites for active food packaging applications.

Efficient and effective use of biopolymers, such as starch, has increasingly prompted interest due to the current environmental challenges. However, starch-based composites still show poor ductility along with water and oxygen permeability, which may not meet the requirements for food packaging standards. In this study, modified starch (m-St), isolated from the avocado seed and synthesized with tert-butyl acetoacetate (t-BAA), was embedded into polylactic acid (PLA) to design new eco-friendly composites. The developed biocomposites were found to exhibit high performance with outstanding mechanical properties in conjunction with remarkable light, water vapor, and oxygen blocking features for food packaging applications. PLA/m-St(1:6) 20 wt% composites showed a dramatic increase in elongation at break (EB%) from 3.35 to 27.80 % (about 730 % enhancement) and exhibited remarkable UV-blocking performance from 16.21 to 83.86 % for UVB, relative to pure PLA. Equally importantly, these biocomposites revealed significant improvement in oxygen and water vapor barrier performance by reducing their values from 1331 to 32.9 cc m-2 day-1 (indicating a remarkable reduction of 97.53 %) and 61.9 to 28 g m-2 day-1, respectively. This study can show the great potential of extracting starch from biowaste resources and transforming it into sustainable bio-based composites as a promising solution for food packaging applications.

Removal of phosphorus and ammonium from municipal wastewater treatment plant effluent by manganese ore in a simulated constructed wetland.

Natural manganese ore (NM) is selected as a distinguished constructed wetland (CW) substrate for nutrient pollutants removal, however, the study on municipal wastewater treatment plant (WWTP) effluent treatment remains scarce. The current study was to investigate the sorption characteristics of NM and the removal efficiency of ammonium and phosphorus from one WWTP effluent in a simulated vertical flow NM constructed wetland (NM-VFCW). Results indicated that NM could effectively sorb ammonium and phosphorus within 24 h, and the desorption ratio was less than 7%. The sorption of ammonium and phosphorus enhanced when increasing the particle size of NM, but was not sensitive with temperature. The removal efficiencies for ammonium and phosphorus were 65% and 76% in NM-VFCW, which were 61% and 31% in gravel VFCW. The much higher removal efficiency for phosphorus was mainly attributed to the precipitation of phosphorus which was identified by the SEM and EDS spectrum. Therefore, the manganese ore sand is highlighted as a powerful substrate for simultaneous advanced removal of phosphorus and ammonium in constructed wetland systems.