Effect of Polyacrylamide Application on Water and Nutrient Movements in Soils

An understanding of nutrient movement in soil is important for developing management strategies to minimize nutrient leaching and surface movement, thus improving nutrient uptake by plants, maintaining a sustainable soil system, and even protecting groundwater quality. Polyacrylamide (PAM) is known as one of soil conditioner that functions to stabilize soil structure, increase infiltration, and reduce surface runoff. This study assesses the effects of PAM on the vertical movement of soil-water and major/minor nutrients (NO3-N, NH3-N, T-N, PO4-P, T-P, K, Ca, Mg, and Fe) in soils. Saturated hydraulic conductivity (Ksat) increases with increasing PAM concen- trations up to 10 mg·L-1 for sand and 20 mg·L-1 for a mixture of sand and clay. Decreases in the loss of soluble nutrients, particularly NH3-N, PO4-P and T-P, are observed as PAM concentrations increase. In contrast, PAM concentration has no effect on nitrate and minor nutrient levels. These results indicate that the application of PAM may be a viable method for protecting water bodies from excessive nutrients and improving nutrient availability for plants.

Factors affecting flocculation performance of synthetic polymer for turbidity control

A multilateral effort into managing nonpoint source pollution from agriculture has gotten much attention for many years. Particularly during the heavy rain season, run-off of turbid water from sloped farmlands, fallow ground and/or unmanaged uplands is deteriorated. Flocculant polymer, commonly used in wastewater treatment facilities, but now exploited to improve control of sediment turbidity by promoting flocculation of particles in construction site. This study used the flocculant polymer to control the discharge of agricultural nonpoint source pollution and focused on the understanding of how soil-water and polymer properties affect flocculation performance. Therefore, a series of flocculation experiments under different conditions was evaluated for better polymer clarification efficiency. Various factors such as flocculant dose, end-over-end inversion of a cylinder, and soil-water properties (pH, NaCl, organic matter) were studied. The effective flocculant dose that fulfilled fast settling rate was 10mg·L-1. Additional findings included that 1) increasing pH decreased the settling rate of soil particle;2) a positive relationship between the percentage of turbidity reduction and a level of salinity in Kaolin suspension was observed, and 3) organic matter in soil solution inhibited PAM adsorption onto soil particles, which caused the reduction of flocculation performance. The findings of this study revealed that flocculant polymer possess good results as a turbidity reducetion measure and couldfurther provide valuable information to make better decision on establishment of Best Management Practice for handling agricultural nonpoint source pollution.

Towards smart farming solutions in the U.S.and South Korea:A comparison of the current status

Smart farming solutions combine information,data software tools,and technology with the intent to improve agricultural production.While smart farming concepts are well described in the literature,the potential societal impacts of smart farming are less conspicuous.To demonstrate how smart farming solutions could influence future agricultural production,agri-business and rural communities and their constituents,this article compares smart farming approaches and reasons behind the pursuit of smart farming solutions by the U.S.and South Korea.The article compares agricultural assets and productivity among the two countries as well as the technical and societal challenges impacting agricultural production as a basis to understanding the motivations behind and pathways for developing smart farming solutions.In doing so,the article compares some of the technological and social advantages and disadvantages of smart farming,dependending on the choice and implementation of smart farming solutions.The South Korean government has implemented a national policy to establish smart farming communities;a concept that addresses the entire agri-food supply chain.In the U.S.,a national plan to develop smart farming technologies does not exist.However,discrete smart farming solutions driven mainly by competition in the private sector have resulted in high-tech solutions that are advancing smart farming concepts.The differences in approaches and reporting of successes and failures between the two countries could facilitate the rate of evolution of successful smart farming solutions,and moreover,could provide pathways to facilitate sustainable development goals in developing countries where smart farming activities are currently underway.

Development of a Hybrid Best Management Practice System for Control of Agricultural Nonpoint Water Pollution

Agricultural drainage ditches play an important role in removing surplus water;however, these can also potentially act as major conduits of agricultural nonpoint source pollutants, including sediment, nitrogen, and phosphorus. A supplementary hybrid system to limit such pollution was developed in this study;this consists of biodegradable fiber check dams, used in combination with a synthetic polymer (Polyacrylamide, PAM). An open channel experiment was conducted to optimize the design of the hybrid system, taking into account a variety of physical and hydraulic conditions. Subsequent field application of the hybrid system improved runoff water quality, such as 10.0% to 98.3% reduction for suspended solids, 25.2% to 98.4% reduction for turbidity, 21.1% to 91.1% increase for BOD, 19.2% to 75.4% increase for COD, 21.0% to 73.3% reduction for T-N, 5.9% to 91.2% reduction for T-P and 35.7% to 97.6% reduction for fecal coliforms. This clearly showed that this hybrid system could play a significant role in supplementing conventional best management practices.

Assessment of physically-based and data-driven models to predict microbial water quality in open channels

In the present study, a physically-based hydraulic modeling tool and a data-driven approach using artificial neural networks （ANNs） were evaluated for their ability to simulate the fate and transport of microorganisms in a water system. To produce reliable data, a pipe network was constructed and a series of experiments using a fecal coliform indicator （Escherichia coli 15597） was conducted. For the physically-based model, morphological （pipe size, link length, slope, etc.） and hydraulic （flow rate） conditions were used as input variables, and for ANNs, water quality parameters （conductivity, pH, and turbidity） were used. Both approaches accurately described the fate and transport of microorganisms （physically-based model： correlation coefficient （R） in the range of 0.914 - 0.977 and ANNs： R in the range of 0.949 - 0.980）, with the exception of one case at a low flow rate （q = 31.56 cm^3/sec）. This study also indicated that these approaches could be complementarily utilized to assess the vulnerability of water facilities and to establish emergency plans based on hypothetical scenarios.

Use of sewage sludge biochar as a catalyst in production of biodiesel through thermally induced transesterification

Sewage sludge(SS)is a residual/semi-solid material produced from industrial and municipal wastewater treatment processes.SS contains a high content of lipids and earth alkaline metals that can be used as catalysts for various chemical applications;however,its valorization has rarely been the focus of research.This study demonstrates that SS could be a promising raw material for biodiesel production and a biochar catalyst to promote the reaction kinetics of alkylation.Thermally induced transesterification of the SS extract(SSE)was performed in comparison with the conventional homogeneous reaction.SS biochar was fabricated via pyrolysis.The highest yield(33.5 wt.%per SSE)of biodiesel production was achieved in 1 min of reaction at 305℃via thermally induced transesterification in the presence of SS biochar,while the yield of biodiesel from(trans)esterification with 5 wt.%H_(2)SO_(4)was less than 1%even after 24 h.The reaction kinetics(<1 min)of thermally induced transesterification was extraordinarily faster than that of conventional transesterification(3-24 h).The porous structure and high content of alkaline species in the SS biochar expedited the reaction kinetics.Consequently,the integrated/hybridized process for thermally induced transesterification and pyrolysis of the solid residue of SS was experimentally proved for the valorization of SS in this study.Considering that SS is being disposed of as a waste material and generates toxic chemicals in the environment,its valorization into value-added biodiesel and a catalyst could be an environmentally benign and sustainable technique.