Phosphorus Fractions and Release Factors in Surface Sediments of a Tailwater River in Xinmi City, a Case Study

The Shuangji River in Xinmi City is a tailwater-type river. Its main water sources are the effluent from the domestic sewage plant, the effluent from the paper industry sewage plant and the coal well. The construction of wastewater treatment facilities in Xinmi city has significantly reduced the amount of total phosphorus (TP) discharged into Shuangji River. However, phosphorus control in rivers where the overlying waters are predominantly tailwaters is still a challenge, especially as the sediment–water interface’s phosphorus exchange mechanism needs to be investigated in detail. In this study, the content and proportion of each phosphorus fraction in the sediment of a tailwater-type river, the Shuangji River, were determined. It was found that the organic phosphorus (OP) and iron-bound phosphorus (Fe-P) content and proportion were high, and the risk of release was relatively high in the section of the river where the overlying water was the tailwater of a sewage plant. Temperature, pH, dissolved oxygen, and hydraulic disturbance were also found to control phosphorus forms’ transformation and release in the sediment. Elevated temperatures mainly stimulated the release of OP and Fe-P from the sediments. The dissolution of calcium-bound phosphorus (Ca-P) is the main pathway for phosphorus release under acidic conditions, whereas, under alkaline conditions, phosphorus release is mainly controlled by ion exchange between OH− and Fe-P and metal oxide-bound phosphorus (Al-P). Aerobic versus anaerobic conditions cause changes in Fe-P content in the sediment mainly by changing Fe ions’ chemical valence. Hydrodynamic disturbance accelerates labile-P release, but once the hydrodynamic disturbance stops, the overlying water dissolved total phosphorus (DTP) concentration rapidly decreases to a similar concentration as before.

Microplastic abundance in beach sediments of the Kiel Fjord, Western Baltic Sea

We assessed the abundance of microplastics (0.2–5 mm) in drift line sediments from three sites in Kiel Fjord, Western Baltic Sea. The first site is intensively used by beach visitors, the second is in close proximity to a sewage plant and the third is polluted with large-sized plastic litter. Samples were split into three grain size classes (0.2–0.5, 0.5–1, 1–5 mm), washed with calcium chloride solution, and filtered at 0.2 mm. Filters were then visually inspected, and a total of 180 fragments was classified as microplastics, of which 39% were analyzed using Raman spectroscopy. At the site that is close to a sewage plant as well as at the site with intense beach use, 1.8 and 4.5 particles (fibers plus fragments) per kg of dry sediment were found, respectively, while particle abundances reached 30.2 per kg of dry sediment at the site with high litter loads. Our data suggest that the fragmentation of large plastic debris at site seems to be a relevant source for microplastics in Western Baltic Sea beach sediments.

Design a project of sewage plant to make the cross-section water quality reach standard

According to regulations, the cross-section of Wangjiawopeng is regarded as a national control section of the Daling River. The water quality of the section must meet the surface water level III standard. According to the survey, the total phosphorus in the effluent from the sewage plant in Jianchang exceeds the standard is the main reason for the failure of the water quality. In order to make the cross-section water quality reaching standard, it is necessary to carry out the advanced treatment of phosphorus in the sewage plant. (1) The precipitation reaction of phosphorus and coagulant in sewage is strengthened by optimizing the type of coagulant, optimizing the dosage of coagulant, and selecting suitable coagulant aids. (2) The removal efficiency of phosphorus is improved by high-speed fiber filtration technology. (3) Phosphorus is removed by flocculation-sedimentation-high-speed fiber filtration technology. Experiments show that the SS in the sewage plant effluent is less than 5mg/L and filter effluent TP is less than 0.2mg/L. The process construction investment is estimated to be 3.9 million yuan, and the operating electricity cost is estimated to be 0.2 cents/m3. The process has the characteristics of reliable processing technology, stable operation, easy maintenance.

Study on the Operation Effect of Constructed Wetland Project for Tailwater Treatment—An Example from a Sewage Plant in Zhejiang Province

The constructed wetland project of tailwater from an urban sewage plant in central Zhejiang was selected to collect water samples in different seasons, and the samples were tested for chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN) and other indicators. The results showed that the operation effect of the constructed wetland project is good when the effluent from the sewage treatment plant meets the Class A discharge standard. Among them, the removal effect of TP was the best, with an average removal rate of 61.52%, reaching the standards of surface water class III and class IV in some tests. Besides, the removal effect of TP was stable and varies little with seasons. The removal rates of COD and TN were relatively low and varied greatly with seasons, which were higher in spring and summer than in autumn and winter, with a negative removal rate of TN in winter. This research provides practical data for optimizing the engineering design parameters and improving the operation management to promote the operation efficiency of the constructed wetland.

Mycobiota of juniper Juniperus x media with symptoms of dieback in sewage plant facilities area in Poznań

The frequency and diversity of fungi in branches, roots and soil was examined in 3–10-years-old diseased Juniperus x media trees growing in the surroundings of the sewage treatment facility in Poznań. Symptoms of branch dieback appeared first on the older parts inside the crown and mostly in the lower part of trees subsequently spreading upwards and outwards. Our analyses included extraction of environmental rDNA from branches, roots and soil, amplification of the rDNA with fungi specific primers and sequencing. Fungal taxa from Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Zygomycota were detected with a total of 695, 135 and 196 taxa in branches, roots and soil, respectively. Fungal communities included plant pathogens, opportunistic pathogens, epiphytes or endophytes, mycorrhizal taxa, saprotrophs common on organic debris and in soil, human and animal pathogens, entomopathogenic taxa, mycoparasites, white and black yeasts, taxa with antagonistic and medicinal properties and lichenized fungi. The frequency of potential plant pathogens was 2.64–33.12% in branches, 0.88% in roots and 1.29–2.93% in soil. The most common pathogens were species from Chalara, Cytospora, Fusarium, Ilyonectria, Mycosphaerella, Setomelanomma (Ascomycota) and Armillaria, Rhizoctonia (Basidiomycota) genera. The less frequent pathogens included species from Leptosphaeria, Lophodermium and Septoria genera. In conclusion, oxygen deficiency and the presence of poisonous gases in the air around the sewage plant is likely to have had damaging effects on plants infected or colonized by opportunistic and facultative parasites.