Algae harvesting and cultivating systems and methods for producing high concentrations of algae product with minimal energy. In an embodiment, a dead-end filtration system and method includes at least one tank and a plurality hollow fiber membranes positioned in the at least one tank. An algae medium is pulled through the hollow fiber membranes such that a retentate and a permeate are produced.

A reverse osmosis treatment device includes: a first pressure vessel for treating an untreated water to produce a primarily treated water and a first permeated water; a second pressure vessel for treating the primarily treated water to produce a secondarily treated water and a second permeated water; a first cleaning solution tank for storing a first cleaning solution for cleaning the first pressure vessel; and a second cleaning solution tank for storing a second cleaning solution for cleaning the second pressure vessel. Each of the first pressure vessel and the second pressure vessel has therein a reverse osmosis membrane element having a reverse osmosis membrane. The first cleaning solution tank is connected to the first concentrate outlet pipe of the first pressure vessel, and the second cleaning solution tank is connected to the inlet pipe for the primarily treated water of the second pressure vessel.

A two-stage electrodialysis system and a method for recovering waste CO.sub.2-lean amine solvent are provided. The system includes an amine solution pretreatment filtering system, a C-A homogeneous membrane electrodialysis device, a BP-A bipolar membrane electrodialysis system, and a CO.sub.2 recovery and capture system. The C-A homogeneous membrane electrodialysis system includes a material chamber, a C-A homogeneous membrane electrodialysis device, a concentrated HSSs waste solution chamber, an electrode solution chamber, and corresponding pipelines and peristaltic pumps. The BP-A bipolar membrane electrodialysis system includes a secondary feed chamber, a BP-A bipolar membrane electrodialysis device, an acid liquor chamber, an electrode solution chamber, and corresponding pipelines and peristaltic pumps. The waste CO.sub.2-lean amine solvent enters the material chamber after passing through the amine solution pretreatment filtering system. The concentrated HSSs waste solution chamber is connected to the secondary feed chamber by a buffer tank.

The present disclosure pertains to filtration methods comprising: passing a first fluid that comprises cells, cell debris and targeted product produced by the cells through a first filter thereby separating the first fluid into a first retentate comprising cells and a first permeate comprising targeted product and cell debris; combining resin beads having affinity for targeted product with the first permeate to form a second fluid containing resin beads with bound target product and cell debris; passing the second fluid through a second filter thereby separating the second fluid into a second retentate comprising resin beads with bound target product and a second permeate comprising cell debris; combining an elution buffer with the second retentate to form a third fluid that comprises a mixture of resin beads and unbound targeted product; and passing the third fluid through a third filter thereby separating resin beads from targeted product.

Liquid solution concentration methods and related systems involving osmosis units and energy recovery are generally described. In some embodiments, an osmotic system has a pump, a first reverse osmosis unit, a second reverse osmosis unit, and one or more energy recovery devices. Various embodiments are directed to features such as balancing streams, recirculation streams, and/or valving that alone or in combination may afford improved energy efficiency and/or system performance. Some embodiments may improve performance of certain types of energy recovery devices in combination with osmosis units, such as isobaric or turbine energy recovery devices.

Methods and systems for producing urea are provided. Ammonia, carbon dioxide, and a carbamate solution can be combined in a pressurized mixer to produce a carbamate reaction mixture. The carbamate reaction mixture can be transferred from the pressurized mixer to a reactor. The carbamate reaction mixture can be heated in the reactor to produce a urea reaction mixture that can include urea, water, ammonia, carbon dioxide, and ammonium carbamate. The urea reaction mixture can be contacted to a membrane to separate an aqueous filtrate and a urea concentrate that can include urea, ammonia, carbon dioxide, and ammonium carbamate. The urea concentrate can be transferred from the reactor to a urea purification system that can include one or more separators and one or more decomposers. The urea concentrate can flow through the urea purification system to produce one or more urea products and one or more carbamate solutions.

An outlet (3) for fluid feed of a first membrane module (1a) is connected to a fluid inlet (2) of a second membrane module (1b), and if further membrane module(s) is/are present, the outlet (3) for fluid feed of a previous membrane module (n−1) is connected to the fluid inlet (2) of a following membrane module (n), and for the last membrane module (n), the outlet (3) for fluid feed is connected to the fluid inlet (2) for fluid feed of the first membrane module (1a). An amount of fluid feed is continuously pumped with pressure PB through a loop of n membrane modules that are serially connected, the fluid feed and permeate flow concurrently through each of the n membrane module(s), generated permeate is continuously drained from each membrane module through a permeate outlet, permeate pressure at the permeate outlet of each membrane module is controlled within a range.

The present invention provides for a method for separating starch from processing solutions containing starch containing plants or roots such as potatoes, sweet potatoes, wheat, corn, tapioca, yams, cassaya, sago, rice, pea, broad bean, horse bean, sorghum, konjac, rye, buckwheat and barley to provide commercially acceptable starch while reducing disposal of solid or liquid waste matter into landfills or water treatment facilities.

A membrane process unit (MPU) is configured to receive a feed stream, subject the feed stream to membrane purification to generate a product stream and a concentrate stream, and subject the concentrate stream to energy recovery to provide at least a portion of energy for membrane purification. A concentrate recycle unit (CRU) is configured to receive the concentrate stream from the MPU, subject the concentrate stream to flow regulation to generate a waste stream and a recycled concentrate stream, and combine the recycled concentrate stream with a raw feed stream to generate the feed stream which is supplied to the MPU. At least one of a flow rate of the raw feed stream, a flow rate of the waste stream, or a flow rate of the recycled concentrate stream is varied, while each of a flow rate of the feed stream, a flow rate of the product stream, and a flow rate of the concentrate stream is maintained substantially fixed.

A process for treating sour water includes combining the sour water with an alkali or alkaline metal hydroxide to produce a sour water mixture, the sour water comprising sulfides, passing an electric current through the sour water mixture, where passing the electric current through the sour water mixture causes at least a portion of the sulfides to react to produce a treated sour water comprising sulfates and having a pH of 7.1 to 9.8, saturating the at least a portion of the sulfates in an aqueous sulfate solution, and separating at least a portion of saturated sulfates from a saturated aqueous sulfate solution.