A method for treating a wastewater comprising phosphates and other nutrients and organic solids comprises feeding the wastewater into an acid gas digester where digestible carbohydrates in the wastewater undergo acidogenesis and acetogenesis forming volatile fatty acids and a suspended solids content to produce an organic acid digest. The acid gas digester effluent is fed into a plurality of harvesting anaerobic digesters connected in series downstream from the acid gas digester. A portion of the solubilized phosphates are precipitated from the wastewater in a first harvesting digester to produce a harvesting digester effluent from the first harvesting digester in the series having a reduced solubilized phosphate content. The harvesting digester effluent is fed into an anaerobic methane digester downstream of the last harvesting digester in the series. Organic solids in the harvesting digester effluent are converted into methane and a digested anaerobic sludge.

The present invention relates to a method for cleaning process water circulated in a paper recycling system, comprising a process water treatment step, which comprises at least one pre-acidification step and at least one anaerobic cleaning step, wherein at least some of the process water to be cleaned is subjected to hydrolysis and acidification in the at least one pre-acidification step and the process water thus treated is then brought into contact with anaerobic microorganisms in the at least one anaerobic cleaning step in order to break down impurities in the process water, wherein at least one saccharide-splitting enzyme is added to the process water before or during the pre-acidification step, and the pH of the process water is set to 8.0 or lower at least during the at least one pre-acidification step and during the at least one anaerobic cleaning step.

Methods of treating animal organic material are disclosed herein. The methods include diluting the animal organic material to produce an organic material slurry, anaerobically digesting the organic material slurry to produce a biogas and a digestate, separating the digestate to produce a digestate solids and a filtrate, removing ammonia from the filtrate, removing organic contaminants and divalent anions from the filtrate, concentrating the filtrate to produce a retentate and a permeate, combining the digestate solids and the retentate to produce a solids product, and returning the permeate to dilute the animal organic material. Systems for treatment of animal organic material are also disclosed herein. The systems include a dilution tank, an anaerobic digester, a first solids-liquid separation subsystem, an ammonia-reducing column, a second solids-liquid separation subsystem, a production water storage tank, and a solids product tank.

A high-load organic wastewater dark fermentation biohydrogen production device and a hydrogen production method are provided. An exhaust port of the production device is communicated with a gas collection region through a gas pipe; a return inlet is arranged at a bottom; a baffle plate is arranged in a two-phase separation device; the baffle plate has a helical shape that makes influent water form a helical centripetal water flow path; one end of an inert gas communicating pipe is connected with an air hole at a bottom of the gas collection region; the other end of the inert gas communicating pipe is communicated with an air intake disc; the inert gas communicating pipe is provided with a connecting hole and an air pump; and the gas collection region is connected with a gas buffer tank and a hydrogen storage tank in sequence. A two-phase separation unit is also provided.

A waste reduction system that utilizes organic solids suspended in a waste stream to produce carboxylic acids, which can then be employed as an input to a microbial fuel cell or other biological processes to further enhance biogas production, is provided. The organic waste stream influent undergoes a multistage fermentation process in which fermentative microorganism metabolize the organic waste materials and produce one or more carboxylic acids, especially short chain fatty acids. The carboxylic acids serve as a food source for bacteria within an anode compartment of an MFC that generates useable electricity therefrom.

The present application discloses a two-phase sulfate reduction device and treatment method for preventing sludge calcification, which belongs to the technical field of wastewater treatment in environmental engineering. The present application combines a two-phase sulfate reduction anaerobic reactor with an alloy catalyst, and reasonably arranges a two-phase connection unit of the alloy catalyst within the device body. By using the special functions of the porous alloy catalyst material to release free electrons into a body of water and polarize the body of water, the electrostatic potential of the body of water is changed, sludge calcification during the wastewater treatment process is prevented, and the treatment efficiency of the anaerobic system for sulfate organic wastewater is ensured.

The present invention relates to a method and to a device for continuous cleaning of process water circulating in a device for treating waste paper. The process water is supplied, from a unit of the device, to an anaerobic reactor comprising a gas separator, and the cleaned process water is returned back to a unit of the device, wherein this unit is selected from: a pulper; screening device; dewatering unit; oxidation/reduction unit; centrifugal screening device; fine screening device; paper-machine mould section; paper-machine press section; reject treatment unit; fibre recovery unit; and drying section; wherein the content of inorganic solids in the reactor is measured and, if this content exceeds a pre-set limit value, process water from the reactor is continuously fed to a solid-liquid separator for separation into a fraction that is depleted of inorganic solids and a fraction that is enriched with inorganic solids, wherein the fraction that is depleted of inorganic solids is returned to the anaerobic reactor and the fraction that is enriched with inorganic solids is conveyed away out of the device, until the content of inorganic solids in the process water is less than the limit value.

An anaerobic biogas plant comprising a digester and a method for the digestion of fresh organic digestion substrate. The digester includes an entry section with an inlet at a first end, a rear section at a second, opposite end, and a middle section arranged between the entry section and the rear section. The digester further includes a stirring unit comprising a shaft extending in the direction from the first end to the second end and having at least one agitating arm for mixing the substrate within the digester. The middle section includes a main outlet and the rear section includes an additional outlet. The digester further includes a separate return line leading from the additional outlet back to the entry section of the digester for allowing a direct return of a minor fraction of digestate removed from the rear section back into the entry section.