Treatment of Industrial Wastewater from Production of Gas Concrete

Autochaved gas concrete is counted to group of light concretes, which volumetric density does not exceed 2 000 kg/m(3). There are several methods of production of the typical gas concrete applied in Poland. Components are only domestic mineral materials: binder cement with the lime or lime itself, aggregate - sand or the mixture of sand with ash or ash from coal burning in power stations; fluffing agent: crumbled aluminum. Reaction of aluminum with calcium hydroxide, coming into being as the result of lime hydration or hydrolysis of cement, causes emission of hydrogen fluffs the mass passing through it and makes possible creation of pores. The air replaces hydrogen in fluffed mass. At present post-production wastewater from PREFABET in Reda is treated in the system, which is presented in the Figure 1. The aim of investigations, presented in this paper, was to work out technology of post-production wastewater treatment to the quality of technological water which can be turned back to production process [7]. Results of investigations of basic contamination parameters of raw wastewater from PREFABET Company in Reda coming from autoclaves are presented in Table 1. There are many methods of industrial wastewater treatment [1,3, 4,5]. Wastewater coming from PRFABET Company were treated under laboratory conditions according to the technology proposed by Authors shown in Figure 2. Overflow from the process of gravitational sedimentation currently piped off to sewage system or to the sludge drying bet located on the terrain of the company does not meet the standards. Furthermore sediments after process of gravitational sedimentation on filter sand makes up currently secondary waste, stored on a heap. Also demand for gas concrete increasing lately on the construction market causes the necessity to increase production, and at the same time causes creation of larger quantities of post-production wastewater. Technology of post-production wastewater treatment proposed by Authors solves presented problems. Post-production wastewater treated according to proposed technology is characterized by 100% reduction of contamination parameters: absorbance, turbidity, biochemical oxygen demand, total organic carbon and ether extract. 99% of reduction was noted for chemical oxygen demand, 63% for total suspension, and 41% for dissolved substances and dry residues. So treated wastewater may again be used in the process of gas concrete production, while dewatered sediments may be utilized in the process of solidification as the addition to the production of plates and cobble stones.