COVID-19 Face Masks as a Long-Term Source of Microplastics in Recycled Urban Green Waste

Following the outbreak of the COVID-19 pandemic in March 2020, many governments recommended or mandated the wearing of fitted face masks to limit the transmission of the SARS-CoV-2 virus via aerosols. Concomitant with the extensive use of non-sterile, surgical-type single-use face masks (SUM) was an increase of such masks, either lost or discarded, in various environmental settings. With their low tensile strength, the spunbond and melt-blown fabrics of the SUM are prone to shredding into small pieces when impacted by lawn cutting equipment. Observations highlight the absence of smaller pieces, which are either wind-dispersed or collected by the mower’s leaf catcher and disposed together with the green waste and then enter the municipal waste stream. As proof-of-concept, experiments using a domestic lawn-mower with different height settings and different grass heights, show that 75% of all pieces of SUM fabric caught in the catcher belonged to sizes below 10 mm2, which under the influence of UV light will decay into microfibers. The implications of SUM generated microplastics are discussed.

Development and Performance Evaluation of a Solar Powered Lawn Mower

The continuous increase in the cost of fuel and the effect of emission of gases from burned fuel into the atmosphere when operating engine powered lawn mower has necessitated the use of the abundant solar energy from the sun as a power source of a lawn mower. A solar powered lawn mower was designed, fabricated and assembled on the basis of the general principle of mowing. The components of the lawn mower are; direct current (DC) motor, rechargeable battery, solar panel, galvanized steel blade of various thicknesses and shapes, and a speed controller. The required torque needed to drive the galvanized steel blade was achieved through the DC motor. The speed of the DC motor was controlled by the speed controller with the resistance in the circuit and allowed the motor to drive the blade at varied speeds. The battery recharged through the solar charging circuit, which comprises of a solar panel and charge controller. Performance evaluation was conducted on the developed mower with various thicknesses (1 mm, 1.5 mm and 2 mm) and shapes of the cutting blade (two, three and four blades). It was found that the cutting efficiency of the mower ranges from 70.50% - 84.10%, also the cutting capacity ranges from 0.05 ha h-1 - 0.27 ha h-1, the uncut area was also found to range from 15.90% - 29.50%.

Battery Powered Lawn Mower

An electric lawn mower supplied from batteries was designed and constructed. Li-ion cells are used because of their high volumetric and weight energy density. Falling prices of these batteries allow such a conception to be practical. Two separate motors are used – one for the traction and the other for the main blade drive. Both motors are brushless DC motors (three-phase synchronous motors with permanent magnets with a specific waveform of the induced voltage). Hall sensors are used to sense the rotor position which is necessary for the control of converters. A high torque outrunner construction of the blade motor was selected to eliminate the need of a gearbox. The used battery capacity of 1.6 kWh was shown to be unnecessarily high for a practical operation – a long operation time (more than 3 hours for one charge), high weight.

Design and Path Planning of Autonomous Solar Lawn Mower

Current conventional lawn mowers have the following drawbacks; high initial costs, increasing engine noise levels, high operating costs due to high fuel consumption rates, the need to implement perimeter wires across the desired lawn mowing field, and high exhaustion of the operator in the long operating time. Hence, the need for a system that can achieve the same cutting effect of the existing lawn mowers with little or no operator’s fatigue, minimized noise pollution and running cost has risen. In present work, design of an autonomous solar lawn mower, a robotic vehicle that cut grass automatically with little human intervention, is discussed. The robotic vehicle is powered by Lithium-Ion batteries and depend on solar power delivered from a solar base station for charging the batteries. The mechanical design of the vehicle is flexible with the ability to control the height of the vehicle during grass mowing. Differential steering, with the implementation of multiple sensors is presented for obstacle avoidance. Also, a Raspberry Pi microcontroller for the image processing application through a camera is used for path planning. Furthermore, a solar based station structure is designed for charging the robotic vehicle batteries with minimized running cost, utilization of renewable energy source, no health hazards, not having any effect on the environment, and human’s effort and time are saved.

The evolution of quiet lawn mowers and their impact on community noise and hearing conservation

Noise measurements of more than 600 lawn mowers were made at 25 feet and at the operator's ear between 2004 and 2021. These data are presented and compared with the measurement of more than 60 mowers in 1973 by the US EPA. With the exception of electric lawn mowers, very little progress has been made quieting lawn mowers. Electric lawn mowers are significantly quieter than gas mowers. Recently, with improvements in battery technology, the performance of electric mowers has improved significantly. There are currently electric push, self-propelled, and ride-on mowers with comparable performance to gas powered mowers. Finally, the impacts of lawn mower noise on community noise and hearing conservation are discussed.