Wastewater recycling in small laundries using MBR-technology

Аннотация

The operation of laundries in Germany is characterized by high water and energy consumption. The business competition, increase of energy cost and active legislative requirements provide for growing demand for wastewater reuse systems (for process water treatment, heat and chemical recovery). In relation to the washing technology the level of water saving is rather high. However, the consumption of fresh water cannot be reduced unless the technologies of wastewater treatment and reuse have been integrated into the existing system. There are few if any examples of using wastewater reuse technologies for small laundries with a capacity of less than 500 kg/day; whereas the available water recycle systems are not efficient enough. A membrane bioreactor with flat submerged ultrafiltration membranes was installed at one of such laundries. The operation of the bioreactor provided for 93% COD reduction, and 90% water return. The quality of permeate was very high (it did not contain suspended solids or microbes) and met the requirements to the reuse in washing process. The cost analysis showed that the use of available permeate heat instead of electrical energy improved the economic efficiency of the laundry operation.

Ключевые слова

ultrafiltration , heat utilization , membrane bioreactor , laundry wastewater , water recycling , industrial wastewater treatment

Experience in Introduction of Up-to-Date Technologies and Methods of Wastewater Sludge Treatment

Summary

New up-to-date technologies are needed for the solution of problems of utilization of sludge generated in the course of wastewater treatment. In St. Petersburg before the introduction of a burning technology the whole sludge preliminary dewatered at centrifuges was stored at special landfills. During the last fourteen years the whole quantity of sludge from the city’s sewerage treatment facilities is burnt. However the sludge accumulated at landfills during preceding years continues to influence negatively on environment. To eliminate this influence it was decided to process the sludge stored at landfills. With that end in view the advanced technology of sludge geotube dewatering has been chosen. Since the summer of 2009 the industrial application of this technology began at the Northern landfill.

Key words

reagent , sludge , flocculant , sludge landfills , geotube , heat utilization

The experience of operating wastewater sludge incineration plants at SUE «Vodokanal of St. Petersburg»

Summary

The experience of operating wastewater sludge incineration plants at the facilities of SUE «Vodokanal of St. Petersburg» is reported. The technology of fluidized-bed sludge incineration is described. The process takes place by means of the calorific capacity of dewatered wastewater sludge. The heat generated in the process of incineration is a secondary energy resource and is utilized in the process for heating blast air, working area and generation of electrical power at the wastewater treatment facilities. The processes of cleaning flue gases generated in the incineration process are compared. The methods of wet and dry flue gas scrubbing are used at the sludge incineration facilities. The quality of scrubbed gases meets the regulatory requirements. The measures taken for improving the reliability and efficiency of operating the plant at the Central wastewater treatment plant of St. Petersburg are described. The experience gained was taken into account in designing sludge incineration facilities at the South-West and North wastewater treatment plants. All the plants adopted the technology of fluidized-bed incineration of sludge. The plants provide for incinerating the entire amount of sludge generated at the wastewater treatment facilities of St. Petersburg.

Key words

heat utilization , wastewater sludges , sludge incinerator , flue gas scrubbing , calorific capacity , secondary energy resource