Water treatment systems for year round consistent achievement of less than 2.5 mg/L of total nitrogen from a gray water starting effluent having about 65 mg/L of total nitrogen. The system may include a septic tank, an anaerobic upflow filter (AUF) that receives wastewater from the septic tank, a recirculating media filter (RMF) that receives wastewater from the AUF, and an anoxic denitrification filter that receives wastewater from the RMF. A drain field may be positioned downstream from the denitrification filter for ultimate disposal of the wastewater. The AUF may reduce the biological oxygen demand (BOD), although its presence also aids the combination of the RMF and denitrification filter that follow to consistently achieve <2.5 mg/L of total nitrogen in the system effluent. An equalization tank, recirculation tank, one or more recycle loops, and various pump stations may also be included. The system may be configured as a two-stage system.

A method of removing contaminants from a solution comprises passing a solution including one or more contaminants through a first cell comprising a first anode chamber and a first cathode chamber, passing a slurry comprising a flowing electrode material through the first anode chamber and the first cathode chamber while applying an electric potential between the first anode chamber and the first cathode chamber to transport anions from the solution to the first anode chamber and to transport cations from the solution to the first cathode chamber, the flowing electrode material comprising a MXene material, wherein M is a metal and X is one or both of carbon and nitrogen, and passing the slurry through a second cell to desorb the anions and cations from the flowing electrode material. Related systems for removing contaminants from a solution, and related methods are disclosed.

A recirculating aquaculture system using a biofloc fermenter and aquaponics may include a breeding water tank that breeds farmed fish, a drum filter that filters breeding water drained from the recirculating aquaculture system; an automatic filtration system in which the breeding water of the drum filter is moved and purified; a biofloc fermentation system that supplies and mixes oxygen to backwash water of the automatic filtration system; and a plant cultivation system that cultivates plant with the breeding water mixed with stable and high-concentration oxygen moved from the biofloc fermentation system.

A plasma activated water production system includes a plasma reactor and a membrane concentrator. The plasma reactor includes an internal cavity, at least one electrically-conductive inlet capillary and outlet capillary. A mixing chamber has a feed gas inlet, a liquid inlet, and a mixed gas and liquid outlet. A power source is provided. The plasma reactor propagates a plasma discharge between the inlet capillary and the outlet capillary. A membrane concentrator includes a water flow channel with a water inlet and a water outlet, a dry gas inlet and a humidified gas outlet. An ion selective membrane is provided, and water will pass through the membrane into the dry gas, and the water leaving the membrane concentrator will have increased concentrations of nitrates, nitrites and hydrogen peroxide. An electrodialysis embodiment and a method of generating plasma activated with increased concentration of nitrates, nitrites and hydrogen peroxide are also disclosed.

A method for decomposing struvite comprises dissolving of a feed material comprising struvite in a mineral acid. Thereby a solution having an acid pH is formed. Magnesium is removed from the solution. The removing of magnesium comprises increasing a pH of the solution to a pH in the range of 4.5 to 6, precipitating magnesium compounds that do not comprise ammonium, and separating the precipitated magnesium compounds from the solution. Thereby, the solution, after the removing of magnesium, comprises an ammonium salt of the mineral acid. An arrangement for performing such a method is also disclosed. Also, a method and arrangement for recovering at least nitrogen from waste material, based on the decomposing of struvite are disclosed.

The present application relates to the field of sewage treatment, and specifically relates to a shortcut nitrification method for sewage treatment. The shortcut nitrification method for sewage treatment provided in the present application comprises the following steps: adding a shortcut nitrification accelerator to sewage. The shortcut nitrification accelerator comprises 2-30 parts by weight of an inorganic hydroxylamine and 0.1-20 parts by weight of an inorganic ammonium salt. The pH of sewage is 6.5-6.95. The shortcut nitrification method for sewage treatment provided in the present application can significantly increase nitrite accumulation rate, and control a biological nitrification reaction at a stage of nitrite accumulation, thereby facilitating a wastewater denitrification process, improving the wastewater treatment effect, and having good engineering application value.

Separation methods and systems for converting high concentrations of animal wastes and other nutrient-rich organic materials into nutrients and other useful products such as struvite and potassium struvite. Advantageously, the system and methods do not require the addition of external chemicals other than an acid and a base.

A process for removing oil and other organics especially lipids from process steams comprising lipids, brown grease, and water is disclosed and a process to remove metals and organics from leachate from landfills and other waste sites that generate contaminated water streams. The process involves adjusting pH and using electrical fields generated by a device comprising electrodes to induce gas bubbles. The gas bubbles facilitate the movement of lipids toward the surface of the solution where they may be skimmed off and recovered.

In this water treatment apparatus and water treatment method, the chlorine demand of raw water W is measured using a chlorine demand meter 9, and sodium hypochlorite corresponding to the chlorine demand is added from a sodium hypochlorite addition means 3. Additionally, the concentration of urea in the raw water W is measured using a urea meter 8, and, on the basis of the urea concentration, additional sodium hypochlorite is added from the sodium hypochlorite addition means 3 and sodium bromide is added from a sodium bromide addition means 4. According to the present invention, it is possible to provide a water treatment method and water treatment apparatus in which a chemical agent required for dissolution of urea is added without excess or insufficiency, even if there is fluctuation in components consuming hypochlorite within the water being treated, and in which urea is stably and reliably removed.

A nitrate-reducing electrode, and methods of making the nitrate-reducing electrode are disclosed. The nitrate reducing electrode includes catalyst particulates disposed on water permeable substrates with the use of electrodeposition, electroless deposition, electrospinning, or thermal treatment. The catalyst particles include metals and metal oxides. The water permeable substrates are preferably made of carbonaceous materials using electrospinning and thermal treatment.