In Thailand, mangosteen (Garcinia mangostana) production is essential for domestic consumption and export. Mangosteen without scars on their surface is considered high-quality fruit. Scars reduce their market demand. The common cause of scars is thrips infestation. Humidity is an important climatic factor that affects the thrips populations. Lower humidity inside the mangosteen canopy increases the thrips numbers. Thus, increasing humidity can control the thrips population. This study developed a smart watering system to increase the humidity inside the mangosteen canopy in Nakhon Si Thammarat province, southern Thailand. This system provided water automatically and increased humidity inside the mangosteen canopy.

Spent coffee grounds are a waste generated in large amounts by the food industry producing instant coffee. While it is used as animal feed, mostly spent coffee grounds are burned. In this study, The spent coffee grounds were modified to be magnetic in order to remove cadmium (II) ion. The magnetic solids are easy to separate from water with a magnet. The biochar was prepared at 400 °C. Several factors that affect the adsorption were studied, such as adsorbent dosage, contact time, initial metal ion concentration and effect of solution pH. At the optimum conditions (the adsorbent dosage 0.1 g l−1, pH 7, time 30 min and the initial concentration 40 mg l−1), the percentage removal of Cd(II) was ∼96%. The surface morphology of the adsorbent showed iron particles with a cubical shape on the adsorbent, with 3–20 μm average diameter. The adsorption data was well fit by a pseudo-second order and a Langmuir isotherm, with the maximum adsorption capacity 10.42 mg/g. The adsorption process was spontaneous and endothermic. The main goal of the study is to re-use the spent coffee grounds waste and use low-cost adsorbent for cadmium (II) removal in aqueous solution. The magnetic biochar was easily manipulated by external magnetic fields after treatment. With good adsorbent performance of the magnetic biochar, spent coffee grounds could be used to treat Cd(II) contamination.

Low-cost biochar was derived from corncob Zea mays L. cultivated in Northern Thailand for animal feed by facile synthesis with in-house modified pyrolysis for 2 h at ∼500°C, ∼10°C min −1 heating rate. Fixed-carbon, ash, %CHNSO and volatile contents of biochar were characterized and compared with pristine biomass. Thermal analysis was performed to monitor the transition of corncob biomass to biochar under the pyrolysis conditions. The physicochemical properties of biochar were investigated by scanning electron microscopy and FT-IR analysis, indicated honeycomb structure on the biochar surface with cylindrical pores and various functional groups, such as carbonyl and phenolic groups. Methylene blue adsorption in aqueous solution by biochar was studied at 25°C. Without any chemical activation on biochar, the maximum removal efficiency of methylene blue by biochar was 16.50 mg g −1 . Effect of the initial concentration and the contact time on removal of methylene blue was studied to archive optimal conditions. The equilibrium adsorption of methylene blue on the biochar was well fit by the Langmuir isotherm. Kinetic of adsorption was perfectly fit by a pseudo-second order dynamic model. The results suggest low-cost corncob biochar prepared by inhouse modified pyrolysis could be utilized in wastewater treatment. List of abbreviationsBET Brunauer-Emmett-Teller C 0 Initial dye concentration (mg l −1 ) C e Equilibrium concentration of dye (mg l −1 ) EIA Environmental impact assessment q e Sorbed dye amount per gram of sorbent at equilibrium (mg g −1 ) q e,cal Calculated amount of dye sorbed per gram of sorbent at equilibrium (mg g −1 ) q e,exp Experimental amount of dye sorbed per gram of sorbent at equilibrium (mg g −1 )qt Sorbed dye amount per gram of sorbent at time t (mg g −1 )K L Langmuir isotherm equilibrium constant representing the energy of sorption (L mg −1 ) K F Freundlich constant representing sorption capacity ((mg g −1 ) (L mg −1 ) n −1 ) k 1 Pseudo-first order rate constant (1 min −1 ) k 2 Pseudo-second order rate constant (g mg −1 min −1 ) MB Methylene blueOPEN ACCESS

Mangosteen (Garcinia mangostana) production is important in Thailand for domestic consumption and export in other countries. High-quality mangosteen is considered when there is no scar on the surface. Thrips infestation is a common cause of scars which reduces the market value of mangosteen. Thrips density is highly affected by humidity; higher humidity decreases thrips numbers. In this study, a smart watering system was designed, developed, and used to increase the humidity and reduce thrips numbers inside mangosteen canopy in Southern Thailand. The system successfully reduced the thrips numbers. This study also shows a negative correlation between humidity and thrips numbers.