| The rapid development of livestock breeding produce lots of dung.The undisposed and improperly processed livestock manure can lead to serious environment pollution,on the other hand,it also seriously affect the human production and living,resulting in social dissatisfaction.Thus,a series of environment problems caused by livestock dung will restrict our country’s livestock breeding industry development seriously.At present,there are two main ways for China’s intensive livestock and poultry farms to deal with livestock manure.One is to produce biogas direct by livestock manure fermentation.But the remaining biogas slurry is a high concentration of pollutants.There are still many difficulties such as where the biogas slurry should go,how to transport the biogas slurry,how to store the biogas slurry and so on.Another way is to separate the dry matter and liquid in the feces through the screw extruder for solidliquid separation,obtaining a solid matter which moisture content is less than 65% and cow manure liquid.The technology to produce organic fertilizers through solid material fermentation has matured.But the moisture content of liquid slurry is up to 90%,especially cow dung liquid slurry.It is a contaminants in colloidal state which is difficult to degrade,difficult to separate and difficult to deal with.The General conditions of cow dung liquid slurry COD(50000-90000mg/L),SS(60000-70000 mg / L)are very high.The commonly used sewage treatment methods such as anaerobic,aerobic and so on are difficult to run.In this paper,the research object are both the cow dung liquid derived from solid-liquid separation of livestock manure and the biogas slurry produced during biogas production by livestock manure fermentation.The cow dung liquid and biogas slurry are rich in organic matter so that they can be used as a medium for growth of photosynthetic bacteria.First of all,the flocculant acting on the cow dung liquid was screened to precipitate the the cow dung liquid again by reduced its SS,turbidity and chroma,obtaining more transparent cow dung water.At the second,the transparent cow dung water was used as a photosynthetic bacteria culture medium.And then the relationship between the growth of photosynthetic bacteria and the treatment of cow dung liquid with different flocculants was discussed.The effects of different inoculation amount,light,adding nutrient(sodium acetate,ammonium chloride)and circulating culture of photosynthetic bacteria were studied.The relative content of photosynthetic bacteria was detected by OD660 method.In the experiment,the flocculant Chitosan was applied to the photosynthetic bacteria to obtain photosynthetic bacterial gel.The flocculant obtained by screening was tested in the Qingbaijiang pasture of New Hope Group and achieved satisfactory results.The photosynthetic bacteria were produced on a large scale by this method,and were applied to tobacco,onions and rice as foliar fertilizers to examine their fertilizer efficiency.Finally,the paper draws the following conclusions:Three kinds of flocculants(named JP-1,LSR and Chitosan)have flocculation effect on cow dung thick water.The amount of water and the turbidity of the three treatments had the effect of reducing the effect.The reduce of chroma in the processing of those three flocculant both can reach to 94%.For the turbidity removal rate,Chitosan and flocculant JP-1 can reach to 99%.After the treatment with the flocculant JP-1,the transparent cow dung water,biogas slurry supernatant and biogas slurry supernatant concentrated liquid can be used as culture medium for photosynthetic bacteria culture.The photosynthetic bacteria grew rapidly in culture medium after 36 hours.The transparent cow dung water treatment Obtained by the treatment with the other two flocculants(named LSR and Chitosan)can not be used to culture photosynthesis bacterial.The reason may be that the residual flocculant LSR and flocculant Chitosan in the supernatant of dairy manure are inhibited by the growth of photosynthetic bacteria.The flocculant JP-1,which was selected in this study,is also suitable for biogas slurry treatment.The supernatant is successfully obtained by flocculation from biogas slurry.In addition,the biogas slurry supernatant can be degraded into water and concentrated liquid by reverse osmosis treatment.The water can reach the standard discharge,and the concentrated liquid can be used as a culture medium to cultivate photosynthetic bacteria,successfully solving the problem of subsequent treatment of biogas slurry.The photosynthetic bacteria were cultured under the condition of temperature 35.5 ℃,pH 7.67-7.98 and light time 72 h,and the absorbance of the bacteria was up to 2.2.And under the same conditions,the livestock and poultry organic wastewater as the medium can be part of the cycle of photosynthetic bacteria continuous culture.The addition of sodium acetate and ammonium chloride to the culture medium of transparent cow dung water was not significant for the growth of photosynthetic bacteria.In this study,the flocculant Chitosan was used for the concentration of photosynthetic bacteria to form photosynthetic bacteria gel.When the dosage of chitosan is 0.02%,the sedimentation efficiency of photosynthetic bacteria is up to 98%.The photosynthetic bacteria gel can keep in the dark for 6 months,and the activity of the photosynthetic bacteria is maintained.The photosynthetic bacteria with absorbance of 2.0 were obtained.The research program was used to ranch field test,and the fresh water of the cow dung was successfully separated to obtain the photosynthetic bacteria in the factory to obtain the photosynthetic bacteria liquid with the average absorbance higher than 2.2.When applied to the tobacco leaves,greatly increased the tobacco leaf production,reducing the occurrence of sickness;applied to the onion,the onion tablets Larger diameter.The technology of photosynthetic bacteria culturing with cow dung concentrate and biogas slurry as raw material is economically feasible and has wide application prospect. |
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