Delivering a low-cost, reliable drip irrigation filtration system for micro-irrigation in developing countries

The cylindrical filters presently used in drip irrigation systems frequently clog, increasing pressure loss and lowering the flow rate through the filters. This work investigates alternative filtration strategies that increase the reliability of, and are compatible with, existing systems. To test different filtration strategies, a drip irrigation test setup was built to measure the pressure loss across different filters as particles accumulated. These experiments found that pleated cartridge filters, with high effective surface area, incurred the lowest pressure losses. More significantly, it was observed during these tests that the filtered out particles settled to the bottom of the filter housing when flow through the filter ceased. This inspired the redesign of the filter housing such that the housing extended far below the filter, providing a catch basin away from the filter for the particles to settle. Fixing the filter independently of the bottom casing significantly improves the overall performance of the filtration system and can be inexpensively manufactured via blow molding. This paper experimentally demonstrates that the cartridge filter inside the redesigned housing can filter out over 2 kg of sand while maintaining less than a .03 bar pressure drop across the filter at a flow rate of 25 l/s. INTRODUCTION Drip irrigation is an efficient way for subsistence farmers in developing countries to increase their crop yields. Drip irrigation systems inexpensively deliver water to the roots of plants via a series of plastic tubes (drip lines) with incrementally spaced holes or emitters, as shown in Figure 1. While drip irrigation delivers water to crops with efficiencies of up to 90% [1], surface irrigation, which has a much lower efficiency of 40-50%, is used in over 80% of the world’s irrigated land [2]. Due to its low water consumption, drip irrigation may enable agriculture in dry areas and increase annual crop yields on existing farmland [3]. Despite its advantages, drip irrigation has not yet reached mainstream acceptance. Historically, the high capital cost of drip irrigation systems has prevented wide-spread adoption, especially for small farmers in developing countries [4]. When compared to the simple labor costs of surface irrigation, the network of drip lines, thousands of emitters, and a pressure source (either a plastic tank for gravity-fed systems or an externally powered pump) necessary for drip irrigation can prove to be prohibitively expensive. Organizations such as iDE have