Effects of sulfate ions on growth and lipid synthesis of Scenedesmus obliquus in synthetic wastewater with various carbon-to-nitrogen ratios altered by different ammonium and nitrate additions.

Producing biodiesel from microalgae is a promising strategy to upgrade energy structure. In this study, effects of sulfate (SO) on lipid synthesis of Scenedesmus obliquus (S. obliquus) cultivated in synthetic wastewater with different carbon to nitrogen (C/N) ratios regulated by ammonium (NH-N) and nitrate (NO-N), separately, were investigated.

Effects of crab disturbance on nitrogen migration and transformation in a coastal tidal flat wetland.

The influence of crab disturbances on nitrogen migration and the transformations of pore water and overlying water in a coastal tidal flat wetland were investigated at the lab scale, and the nitrogen exchange flux at the sediment-water interface was calculated. The results showed that crabs, combined with tidal effects, had significant effects on the microtopography of the studied crab box. In addition, there was no significant difference in the concentrations of NH-N, NO-N, or TN between two points in the horizontal direction (P > 0.

Parameter-efficient bioclogging model: calibration and comparison with laboratory data.

A parameter-efficient bioclogging model coupled with hydrodynamics was developed with a stepwise numerical calculation. Column lab tests were carried out to calibrate and verify the bioclogging model developed in this paper. The results showed that the experimental data fit well with the simulation data, which indicated that the developed model was reasonable.

Influence of clogging and resting processes on flow patterns in vertical flow constructed wetlands.

Vertical flow constructed wetlands are widely used for removing pollutants from wastewater. Substrate clogging is an operational challenge of constructed wetlands, which can result in impeded water flow and finally a significant decline in the ability of the system to treat the wastewater. The entire clogging process in a vertical flow constructed wetland (VFCW) was quantitatively analyzed by measurements of hydraulic conductivity.

High-throughput sequencing analysis of bacterial community spatiotemporal distribution in response to clogging in vertical flow constructed wetlands.

The aim of this study was to characterize bacterial communities in vertical flow constructed wetlands (VFCWs) using Illumina high-throughput sequencing. The bacterial communities developed lower richness and diversity in response to clogging. Bacterial diversity did not overtly decrease with depth.

Evapotranspiration versus oxygen intrusion: which is the main force in alleviating bioclogging of vertical-flow constructed wetlands during a resting operation?

Clogging is the most significant challenge limiting the application of constructed wetlands. Application of a forced resting period is a practical way to relieve clogging, particularly bioclogging. To reveal the alleviation mechanisms behind such a resting operation, evapotranspiration and oxygen flux were studied during a resting period in a laboratory vertical-flow constructed wetland model through physical simulation and numerical model analysis.

Migration and degradation of swine farm tetracyclines at the river catchment scale: Can the multi-pond system mitigate pollution risk to receiving rivers?

The study investigated the degradation behaviors of swine farm tetracyclines (TCs) at a catchment scale and explored whether multi-pond systems could be beneficial to the interception of TCs so as to reduce the pollution risk to receiving rivers. The occurrence and migration of 12 kinds of tetracycline antibiotics, including their degradation products, were studied in four swine farms of the Meijiang River basin in China. The migration paths of the TCs were examined through sampling and analyzing the soil and/or sediment at different points along the swine wastewater outlet, which included sewer, sewage pond, mixed-canal (stream and sewage), farmland (paddy and upland soil) and finally the river.

Applying a resting operation to alleviate bioclogging in vertical flow constructed wetlands: an experimental lab evaluation.

The aim of this study is to evaluate the effects of and analyze the reasons for applying a resting operation to alleviate bioclogging in vertical flow constructed wetlands (VFCWs). In parallel, three groups of laboratory-scale VFCWs were continuously fed with prepared wastewater (BOD = 600 mg/L) at a relatively high hydraulic loading rate of 0.5 m(3)/m(2)·d until clogging.

Applying solubilization treatment to reverse clogging in laboratory-scale vertical flow constructed wetlands.

Substrate clogging is characterized as a frequently occurring operational problem for subsurface-flow constructed wetlands. The application of solubilization treatment to reduce clogging was tested in lab-scaled setups to provide a promising solution. The performance of solubilization treatment on reducing clogging and the related effects on plants and biofilms in the wetland system were investigated in this paper.