Verfahren zur anaeroben Aufbereitung von Abwasser

摘要

The process for the continuous purification of wastewater in papermaking, comprises feeding wastewater to an anaerobic reactor (12), contacting the water in the reactor with anaerobic microorganisms to degrade contaminants present in water, and continuously discharging the purified wastewater from the anaerobic reactor. The wastewater to be purified is supplied to a pressure-release flotation device (30) before feeding into the anaerobic reactor. The wastewater from the pressure-release flotation device is supplied directly or indirectly to the anaerobic reactor. The process for the continuous purification of wastewater in papermaking, comprises feeding wastewater to an anaerobic reactor (12), contacting the water in the reactor with anaerobic microorganisms to degrade contaminants present in water, and continuously discharging the purified wastewater from the anaerobic reactor. The wastewater to be purified is supplied to a pressure-release flotation device (30) before feeding into the anaerobic reactor. The wastewater from the pressure-release flotation device is supplied directly or indirectly to the anaerobic reactor. Some of the wastewater is subjected to a pressure-release flotation step before the supply of the anaerobic reactor or after the discharging from the anaerobic reactor, to delime the water to some extent. The wastewater in the pressure-release flotation step is adjusted on neutral or alkaline pH-value between 7.5-8.5 and is subjected with pressure, before the treated wastewater is exposed to a reduced pressure. A precipitating agent and/or flocculating agent are added before the wastewater or during pressure-release flotation step. The process comprises pre-acidification step, in which the wastewater is subjected to a hydrolysis and/or an acidogenesis in a pre-acidification reactor (14). The wastewater is led into the anaerobic reactor after the pressure-release flotation step and/or into the pre-acidification reactor. The temperature of the wastewater supplied to the reactor is regulated and/or monitored. The wastewater to be purified is continuously supplied to pressure-release flotation device, in which the pressure-release flotation step takes place. The wastewater is mixed with a part of the wastewater continuously discharged from the anaerobic reactor and from the pressure-release flotation device. The pressure-release flotation device continuously discharges partly decalcified wastewater, which is led into a pre-acidification reactor and/or into the anaerobic reactor. The decalcified wastewater is discharged partially from the device and again used in production process. The wastewater is continuously supplied to pre-acidification reactor and is led into the anaerobic reactor. The purified wastewater is led partially into pressure-release flotation device. The pressure-release flotation device continuously discharges the wastewater, which is led back into the pre-acidification reactor and/or directly into anaerobic reactor or via a mixing device arranged between the pre-acidification reactor and anaerobic reactor. The purified wastewater is separated into two partial flows, and one of the partial flows is led into the pressure-release flotation device. The partial flow of 30-50% is supplied to the pressure-release flotation device, related to the total flow discharged from the anaerobic reactor. The water hardness in the pressure-release flotation step is minimized about 40%. An independent claim is included for a device for the continuous purification of wastewater in papermaking.