基于低速离心分离技术的水禽粪污预处理装置研发

    Development of waterfowl manure pretreatment device based on low speed centrifugal separation technology

    • 摘要: 针对水禽粪污和沼液类较黏稠、固形物颗粒小的污水,现有分离技术存在能耗高、分离效率低等问题,该研究提出一种绿色节能的离心分离方法。通过单因素试验,明确筛网目数、离心转速和分离时间对水禽粪污中主要污染物去除效果的影响。采用二次通用旋转设计进行优化试验,得到低速离心分离技术的优化参数组合。经过离心分离机试验验证,当分离时间为3 min、筛网目数为120目(孔径大小为0.13 mm)、离心转速为700 r/min时取得较好分离效果,此时水禽粪污总固体(total solid,TS)去除率为50.20%,挥发性固体(volatile solid,VS)去除率为57.59%,化学需氧量去除率为5.39%,氨氮去除率为4.39%,总磷去除率为5.76%。以试验结果为依据研发分离装置并实地运行,分离效果(TS去除率为53.21%,VS去除率为58.61%)与高速离心机械相当,且每吨污水处理成本相较卧式螺旋离心机降低近22%,表明低速离心分离技术可行,为去除水禽粪污中悬浮性固体提供了一种新方案,具备工程化推广意义。

       

      Abstract: Resource utilization of animal manure can be used to reduce environmental pollution in the recycling of nutrients from the manure. Solid-liquid separation can serve as one of the pretreatment to improve the utilization efficiency for cost saving. However, existing treatments cannot fully meet the large-scale production in recent years, such as the high energy consumption, and low separation efficiency for sewage with a high viscosity and small solid particles, such as waterfowl feces and biogas slurry. Single-factor experiments were carried out to determine the effects of the centrifugal separation time, mesh number, and centrifugal separation speed on the separation effect of waterfowl feces. The quadratic general rotary unitized design was used to implement an optimization test. The optimal combination of parameters was obtained after the analysis of the data and consideration of the actual operating conditions. The data were analyzed by Excel 2016, Origin 2021, and Design Expert 12. The results showed that the treatment was achieved in better solid removal with the shorter hydraulic retention time of subsequent biochemical treatment. The content of pollutants in the waterfowl feces showed a trend of gradual decrease with the increase of screen mesh. The reason was that the aperture size decreased, as the number of sieve meshes increased. The larger solid particles were passed through to be trapped in the filter bag. The better performance of solid-liquid separation of waterfowl feces was achieved with the increase in centrifugal separation speed, due to the retention effect of the screen and stronger centrifugal action. The solids removal effect cannot be significantly enhanced under the action of low-speed centrifugation when the centrifugal separation speed continued to increase. The separation effect of free water was mainly achieved, where the adsorbed water was not strong enough to detach from the inter-particle adsorption. The thickness of the filter cake in the filter bag gradually increased, as the separation time increased. The solid particles were retained, whereas, the liquid also had sufficient time to separate through the filter cake. But the excessive separation time led to the clogging of the screen pores, where the liquid was difficult to pass through the filter cake. After the centrifuge separation optimization test and verification, the optimal separation effect was obtained, when the centrifuge separation time, mesh number, and centrifugal separation speed were set as 3 min, 120 mesh (aperture size 0.13 mm), and 700 r/min, respectively. At the same time, the removal rates of total solid (TS), volatile solids (VS), chemical oxygen demand (COD), NH4+-N, and total phosphorus (TP) were 50.20%, 57.59%, 5.39%, 4.39%, and 5.76%, respectively. The separation effects (removal rates of TS and VS were 53.21% and 58.61%) were comparable to the separation effect of a high-speed centrifuge after the field operation of the prototype. The treatment cost was reduced by nearly 22% for one ton of sewage, indicating the feasible low-speed differential centrifugal separation. This finding can provide a promising scheme for the removal of suspended solids from the waterfowl feces in engineering popularization.

       

    /

    返回文章
    返回