Rapid Sand Filter

Benteng pengolahan air adalah filter. Bahkan IPAM disebut instalasi filtrasi. Filter dapat menghasilkan air yang sangat jernih apalagi kalau dilengkapi dengan unit koagulasi, flokulasi dan sedimentasi. Jantung pengolahan air pada filter adalah medianya (filter bed). Di dalam media inilah terjadi penyisihan kekeruhan dan mikroba. Mekanisme yang terjadi di dalam media RSF adalah straining, sedimentasi, flokulasi, difusi, inersia, intersepsi, hidrodinamika. Semua mekanisme ini terjadi di dalam rongga mikro atau parasitas (perviousness), yaitu rasio volume rongga di dalam media filter terhadap volume kosong bak filter. Parasitas berbeda dengan porositas (porosity). Porositas adalah rongga di dalam butiran media bukan rongga antara butir-butir media filter.

Point-of-use upflow sand filter for rural water treatment using natural local sand: Understanding and predicting pressure drop

A simple, small scale upflow sand filter was fabricated using a locally obtained sands at three different rivers in Sabah, Malaysia: Liwagu River (SL), Tamparuli River (ST), and Kaingaran River (SK). The grain size, porosity, bulk density, particle density and sphericity of the sands were characterized to associate with the corresponding pressure drop across the sand bed. The highest pressure drop per unit length for SK, PT, and SL are 15.85 kPa m-1 at 0.747 m s-1 vs, 10.18 kPa m-1 at 0.352 m s-1 vs, and 9.24 kPa m-1 at 0.747 m s-1 vs, respectively. The pressure drop per unit length at different filter bed depth were plotted, and compared against three theoretical models of Ergun, Kozeny-Carman, and Fair and Hatch. By analyzing the experimental-theoretical comparison using RMSE and Chi-Test, prediction of pressure drop in an upflow sand filter is able to be predicted using the Kozeny-Carman equation preceding filter bed fluidization and subsequently Fair and Hatch’s equation after bed is fluidized.

The Study on Internal Flow Characteristics of Disc Filter under Different Working Condition

A disc filter (DF) is an important component in a micro irrigation system. However, it has a high head loss and low filtration efficiency, which can lead to the inoperability of micro irrigation systems. To improve the filtration ability and to decrease the pressure loss of the irrigation system, it is necessary to internalize the hydraulic characteristics of DFs. In this study, the filter bed of a DF was divided into three parts, i.e., upper, middle, and lower, which were wrapped with a transparent film. The wrapped part was completely blocked. The purpose was to analyze the hydraulic characteristics of different clogged conditions in three types of filters under four types of flows. In addition, we attempted to simulate the filter operation process with computational fluid dynamics, based on two aspects—a macroscopic model and a simplified model. The results showed that the patterns of head loss among all of the DFs was consistent, and the macroscopic model that treated filter bed as a porous medium could express the measured results. The macroscopic models observed that there was a circular flow in the DF, and the flow velocity presented a symmetrical distribution in a horizontal direction. The middle of the filter element appeared in a high-pressure area and demonstrated the highest head loss, which may be the main flow area of the DF, and the inner flow characteristics of the DF were consistent under different conditions. The simplified models showed that the main flow area is near the filter bed in the inner DF, and the flow is tangent to the filter bed between 45 and 90 degrees in a horizontal direction. The uneven distribution of velocity and pressure on the filter bed might be necessary factors to impact filter efficiency.

Optimization of operational parameters for the treatment of roof-harvested rainwater with biologically synthesised nanosilver coated on sand

Rainwater is a major source of drinking water in developing countries. Roof-harvested rainwater is generally microbiologically contaminated and thus need to be treated effectively to meet drinking standards. Filtration of rainwater with silver nanoparticles coated on sand enhances the microbial removal efficiency. In this study, the filtration parameters of treating rainwater with biologically synthesized nanosilver coated sand are optimized. Of the various synthesis methods, the biological method of was chosen due to benefits such as cost-effectiveness and eco-friendly nature. Silver nanoparticles was synthesised using with papaya fruit extract and then coated on sand. The synthesized nanosilver coated sand was subjected to characterization methods such as Energy Dispersive Spectroscopy and X-Ray Diffraction analysis. With silver coated sand as control, multiple long duration tests were performed to treat rainwater with nanosilver coated sand to find the optimal values for filtration parameters such as filter bed depth and Empty Bed Contact Time (EBCT). The crystallite size of the nanosilver coated sand was found to be 43.8 nm. The optimal values for filter bed depth and EBCT was found to be 12 cm and 15minutes respectively. The rainwater treated with nanosilver coated sand met drinking water standards IS 10500: 2012 until the media got exhausted.