A water purifier includes a raw water flow path into which raw water is introduced, a clean water flow path connected to the raw water flow path and having a water discharge nozzle disposed at an end, a filter device disposed in the clean water flow path, and to which a filter is installable to filter the raw water, a drain flow path branched off from the clean water flow path between the filter and the water discharge nozzle and connected to a drain port to drain water in the clean water flow path to outside, a drain valve configured to open or close the drain flow path, and a controller configured to determine a remaining life of the filter on a point in time at which the filter has been replaced and control the drain valve to perform a cleaning operation based on the remaining life of the filter.

A raw water channel spacer capable of suppressing formation of a concentration polarization layer in a region in the vicinity of a separation membrane in a raw water channel, and a spiral wound membrane element including the same are provided. A raw water channel spacer is formed by superposing a first yarn row and a second yarn row, and includes alternately a first mesh structure having a configuration in which first rectangular meshes formed of the yarn rows are continuous in an extending direction of the second yarn row, and a second mesh structure having a configuration in which meshes are continuous in the extending direction of the second yarn row such that an interval in the second yarn row is smaller than an interval of the second yarn row forming the first mesh structure.

A raw water channel spacer capable of suppressing formation of a concentration polarization layer in a region in the vicinity of a separation membrane in a raw water channel, and a spiral wound membrane element including the same are provided. A raw water channel spacer is formed by superposing a first yarn row and a second yarn row, and includes alternately a first mesh structure having a configuration in which first rectangular meshes formed of the yarn rows are continuous in an extending direction of the second yarn row, and a second mesh structure having a configuration in which meshes are continuous in the extending direction of the second yarn row such that an interval in the second yarn row is smaller than an interval of the second yarn row forming the first mesh structure.

A water treatment control system includes an aerobic tank in which aerobic treatment is carried out, an aerobic tank aeration device that aerates to-be-treated water in the aerobic tank, a membrane filtration tank including a separation membrane that filters the to-be-treated water treated in the aerobic tank, a membrane filtration tank measurement instrument that measures the ammonia concentration of the to-be-treated water in the membrane filtration tank, as a membrane filtration tank ammonia concentration measurement value, and an aerobic tank aeration air volume calculation device that sets the aerobic tank aeration air volume of the aerobic tank aeration device on the basis of the membrane filtration tank ammonia concentration measurement value.

A water treatment control system includes an aerobic tank in which aerobic treatment is carried out, an aerobic tank aeration device that aerates to-be-treated water in the aerobic tank, a membrane filtration tank including a separation membrane that filters the to-be-treated water treated in the aerobic tank, a membrane filtration tank measurement instrument that measures the ammonia concentration of the to-be-treated water in the membrane filtration tank, as a membrane filtration tank ammonia concentration measurement value, and an aerobic tank aeration air volume calculation device that sets the aerobic tank aeration air volume of the aerobic tank aeration device on the basis of the membrane filtration tank ammonia concentration measurement value.

A method of predicting membrane fouling in a reverse osmosis process includes collecting information relative to the reverse osmosis process being performed over a predetermined period of time, the collected information including a process factor and a water quality factor, the process factor including a produced water flow rate; calculating a salt removal rate and a pressure drop based on the collected information; normalizing the produced water flow rate, the salt removal rate, and the pressure drop; generating a prediction equation using normalized values of the produced water flow rate, the salt removal rate, and the pressure drop values; and predicting membrane fouling through the generated prediction equation to determine a chemical cleaning time. Process and water quality factors are normalized to temperature and/or flow rate, and the prediction equation uses the normalized factors. Both short-term and long-term predictions are made for chemical cleaning time and membrane module replacement time.

A method of predicting membrane fouling in a reverse osmosis process includes collecting information relative to the reverse osmosis process being performed over a predetermined period of time, the collected information including a process factor and a water quality factor, the process factor including a produced water flow rate; calculating a salt removal rate and a pressure drop based on the collected information; normalizing the produced water flow rate, the salt removal rate, and the pressure drop; generating a prediction equation using normalized values of the produced water flow rate, the salt removal rate, and the pressure drop values; and predicting membrane fouling through the generated prediction equation to determine a chemical cleaning time. Process and water quality factors are normalized to temperature and/or flow rate, and the prediction equation uses the normalized factors. Both short-term and long-term predictions are made for chemical cleaning time and membrane module replacement time.

The present disclosure provides a physicochemical water treatment process using a microfiber filter coated with a coagulant, including: a) performing a pressurized filtration by supplying raw water to an upper portion of a pressurized microfiber filtering device including a microfiber filter coated with a coagulant; b) backwashing the microfiber filter by supplying backwashing water and air from a lower portion of the microfiber filtering device; and c) after the backwashing of the microfiber filter is completed, coating the microfiber filter with the coagulant by supplying the coagulant together with the backwashing water, wherein backwashing wastewater of the pressurized microfiber filtering device is concentrated by the suction type microfiber filter coated with the coagulant and transferred to a dehydrator.

A cleaning method of a membrane filtration system in which a plurality of modules including an inlet side region and an outlet side region separated by a filtration membrane are connected in parallel by a common blow header pipe in the inlet side region, the method including backwashing and blowing in which after the backwashing is started, gas is introduced into the plurality of modules through a blow header pipe. The method further includes forming, before the blowing is started, a gas layer across an entire longitudinal direction of the blow header pipe.

A cleaning method of a membrane filtration system in which a plurality of modules including an inlet side region and an outlet side region separated by a filtration membrane are connected in parallel by a common blow header pipe in the inlet side region, the method including backwashing and blowing in which after the backwashing is started, gas is introduced into the plurality of modules through a blow header pipe. The method further includes forming, before the blowing is started, a gas layer across an entire longitudinal direction of the blow header pipe.