| Cocoon wastewater is a type of wastewater with high nitrogen, high phosphorus and high organic concentration which is produced in waste cocoon treating processing. At the present time, researches of cocoon wastewater are only about COD removal and silk gum recovery, they lack researches on nitrogen and phosphorus removal of this type of water.This paper aimes at developing the cocoon wastewater treating technique with high efficiency and low energy consumption.Based on the overview of high nitrogen ,high phosphorus and high organic concentration removal techniques, the pretreatment efficiency of ASBBR reactor and acid precipitation has been studied. Aiming at the characteristics of cocoon waste water with high phosphorus concentration, the efficiency of chemical,biochemical and bio-chemical co-operating phosphorus removal technology has been compared by inspecting the organic loading , operating mode, technical combination, drug variety and dose of both. At the same time, system research has been developed regarding highly-efficient denitrogen technique of SBBR reactor. By studying the influence of the organic loading rate,nitrogen loading rate,DO,temperature and carbon source on the nitrogen removal performance of the reactor, critical parameters and control condition for high efficiency SND has been obtained."ASBBR+Double- stage SBBR+Chemical flocculation"group technique has been presented by integration and optimization. Effluent can achieve the standard of discharge and recycle-water when reactor working under the best operarting mode. The main conclusions are described as follows:①Under the operating conditions of ASBBR biofilm density =70%,OLR =3kgBOD5/m3·d, operating mode was inlet 0.5h-aeration 23h-idling 0.5,temperature were 20℃a nd 30℃, the effluent CODcr concentration was 1415 mg/L and 1105mg/L ,with the 84.22% and 97.68% of removal rate respectively.②When pH=4.2, the CODcr removal rate of cocoon wastewater was 76.1%, NH4+-N was 28.33% and TN was 32.97% by acid precipitation. Temperature has no significant effect on the acid precipitation process. The effluent pH value needs to be adjusted after acid precipitation, thus increase the running cost and complicate the operation. Acid precipitation suits the sericin recycle as a pretreatment process.③The experimental results showed: the bio-phosphorus removal—bio-denitrification—chemical phosphorus removal combination technology used to anaerobic effluent of cocoon waste water was economic and highly efficient. When organic load rate (OLR) was 3kgCOD/m3·d in the bio-phosphorus removal SBBR technology unit, operating mode was influent 0.5h—anaerobic2h—aerobic4h—depost1h—effluent0.5h, and 133 mg/L poly aluminum chloride was added in chemical phosphorus removal technology; these could make the influent with 4300 mg/LCOD and 114 mg/L PO43- to become the effluent with 91 mg/L COD and 0.27 mg/L PO43-. The totalηCOD is 97.8%,ηPO43- is 99.7%, theηCOD borne by bio-phosphorus removal technology unit and chemical-phosphorus removal technology unit was respectively 43% and 11%, and theηPO43- borne by bio-phosphorus removal technology unit and chemical-phosphorus removal technology unit was respectively 70% and 29.7%.④Under the operating conditions of SBBR biofilm density =35%,OLR =0.3kgBOD5/m3·d, NLR=0.6kgN/m3·d , there exsisted significant SND phenomenon in SBBR reactor. Effluent NH4+-N and TN concentration was 1.09mg/L and 36.76mg/L ,the removal rate was 98% and 85.7% respectively. After refilling the 1:1.25 carbon source in SBBR in 4th hour .The effluent TN concentration was decreased to 17.39 mg/L which meets the general discharge standard.⑤By applying the"ASBBR+two-stageSBBR+Chemical flocculating"combination process,under the operating conditions of ASBBR biofilm density =70%,OLR =3kgBOD5/m3·d; The first-stage SBBR biofilm density =35%,OLR =0.3kgBOD5/m3·d, NLR=0.6 kgN/m3·d, operating mode was aeration 4h-idling 2h;The second-stage SBBR biofilm density =35%,OLR =0.3kgBOD5/m3·d, NLR=0.6kgN/m3·d, operating mode was aeration 4h , adding 1:1.25 carbon source in SBBR in 4th hour. When adding 133mg/l PAC in chemical flocculating process, the effluent of CODcr,NH4+-N,TN and PO43- was 93 mg/L,3.01 mg/L,17.39 mg/L and 0.23 mg/L respectively. All the index meet the general discharge standard and the requirement of reuse water of silk factory. The effluent can be reused as process water and achieve zero draining.The above research will provide scientific evidence for producing high efficiency ,low-investment, low-cost and simple-management cocoon sewage treatment.
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