Study On The Development And Application In BAF Of The New Unburned Fly Ash Ceramsite

Fly ash is discharged heavily in our country, which cause land occupation andpollute the environment. Fly ash ceramisite can be used as the filter of BAF, whichis an important way of comprehensive utilization of fly ash. At present, theproduction of fly ash ceramisite all use sintering process which is more mature buthas high energy consumption, heavy pollution and high cost. In contrast, unburnedprocess is more energy saving and environmental protection, which cost lowly.Unburned ceramisite is still in the development stage in our country, with theshortage of high packing density, low intensity and low specific surface area, thus,it was not popularized and applied though there was product. This paper developednew fly ash unburned ceramiste that could be used as filler of BAF. The ceramistewas low cost and of high efficiency, which could overcome the pollution of fly ashto a certain extent, making the unburned process being spread.In this study, fly ash unburned ceramsite was made for the standard ofartificial filter used in water treatment to control raw material and process. Thepreparation process of the new unburned ceramsite was:5%NaOH pretreatmentfly ash63%, CaO5%, cement20%straw ash6%, sludge6%, add water32%aftermixing of raw materials （relative to dry material）, wet seat conservation24h afterballing, steam curing under80℃for12h. The main performance index werebroken rate4.2%, packing density687kg/m³, apparent density1573kg/m³,porosity52.2%, specific surface area9.78m²/g （traditional ceramsite3.29m²/g）.The result showed that the strength of ceramsite was the effect of both SiO₂andCa₂SiO₄·H₂O. Straw ash and sludge can increase the specific surface area of theceramsite. Straw ash was mainly to promote the formation of holes and sludge hadan effect on micro porous and macro porous.cdeerteacTmtihsoeitn e b moafsa icdt ehp eroc pounelerdwti m esc,ee erletaa tmcheshiing toxicity, adsorption properties and bio-affinity tset anwdearred oanf a“lfyizlteedr. usTehde forer sturelta tmsheonwt eodf atrhtaift ictihaelceramsite（CJ/T299-2008）” and leaching toxicity requirements, what’s more, the adsorption and biological affinity were superior to conventional sinteringceramsite. New and traditional ceramsite were input in BAF to compare onbiofilm and start normal operation of the treatment effect, surface microbialbiomass and backwash performance. It showed that new ceramsite had an easierbiofilm formation ability than traditional ceramsite. In normal operation phase,the COD, ammonia nitrogen, total nitrogen degradation capacity of new typewere better than traditional ones. The new ceramisite was more suitable for thegrowth of microorganisms, particularly, it could play a certain role in promotingthe growth of nitrifying bacteria.The preparation method of new ceramsite was economical and energy saving.The production costs of1m³ceramsite was aboutï¿¥420-550（traditional onesï¿¥700-900）, fuel costs was onlyï¿¥0-132（The unburned ceramsite could use wasteheat of power plant for steam curing without costs）, far below the sinteringceramisite withï¿¥240-480, which could reduce energy consumption greatly, ofremarkable economical benefit.