JPH06144979A - Effective utilization of excess sludge - Google Patents

Abstract

PURPOSE:To develop the effective utilization by which excess sludge of food factories and night soil or sewerage treatment plants can be recycled. CONSTITUTION:When quick lime (calcium oxide) is added to the excess sludge, the quick lime reacts highly exothermically with water in the sludge to form calcium hydroxide (slaked lime). As a result various microorganisms in the sludge is completely killed and the sludge is partly hydrolyzed by the high alkalinity and temperature. Thereafter by adding straws, sawdust, and further tuff loam and leaf mold to the sludge and by fermenting the mixture, a completely aged organic manure can be produced. At the time of applying the manure to vegetables, excellent growth promotion of the vegetables without any adverse effect on them resulting from any applied amount of the manure can be attained. On the other hand sulfuric acid is added to the excess sludge and the resulting sludge is neutralized with an aqueous suspension of slaked line and then sawdust is added to it. The mixture is sufficiently blended while stirring. At the time of using the mixture thus produced as a culture medium of Cortinellus shiitake (mushroom) and Pholiota nameko (mushroom), the growth of the hyphae of the mushrooms is remarkably promoted and also good yields and qualities of Cortinellus shiitake and Pholiota nameko can be attained.

Description

Description: (0001) Industrial application field Effective use of excess sludge (environmental conservation field) (0002) Conventional technology Since excess sludge is a microorganism and an organic substance, it is buried or left as it is. If it does, it will decompose and generate hydrogen sulfide gas and other malodorous gas, which causes secondary pollution. Therefore, as the main treatment method that is currently performed, agglomeration is performed with a polymer agent, then water is squeezed to about 85% with a dehydrator, then dried and incinerated for burying. In addition, recently, it has been attempted to ferment surplus sludge with microorganisms to form organic compost.

(0003) Problems to be Solved by the Invention The current regular treatment method for excess sludge requires a great running cost up to the dehydration step, the drying step, the incineration step, and the final landfill disposal of the incinerated ash. Recently, attempts have been made to compost organic matter with excess sludge, but such an approach can be said to be the most significant method for a recycling system. Therefore, it is considered that a simple and low-cost treatment method is an issue for effective use of excess sludge.

(0004) Means and Actions for Solving the Problems In the present invention, recycling of excess sludge was attempted to be used as a fertilizer and a mushroom cultivation medium. It is well known that quick lime (calcium oxide) and sulfuric acid are used for the neutralization of factory effluent and the chemical treatment of human waste, but there is no example of effective use of excess sludge. The present inventor added these to the excess sludge obtained by the activated sludge method, and then added straw and sawdust and mixed well. As a result, they have invented that a fertilizer and a medium that are completely different from the conventional excess sludge can be produced. First, when quick lime is added to excess sludge, quick lime emits high heat with water and combines to become calcium hydroxide, that is, slaked lime. In this case, when water content is 100% and 25% quicklime is added, the temperature is raised by 50 ° C or more. It is considered that strong alkalinity and high temperature kill fungi, protozoa, and nematodes in excess sludge, and some sludge is hydrolyzed by alkali. Then, dried straws and sawdust were added to produce a slaked lime fertilizer rich in organic matter and having good storage stability. Further, it was found that an odorless fully-ripened organic fertilizer can be produced by further adding acid soil red soil to this product, cutting it well, and then adding mulch soil to ferment it. On the other hand, when the excess sludge is first self-digested and then concentrated sulfuric acid is added and heated, the microorganisms in the sludge are partially hydrolyzed by acid. Then, when slaked lime suspended in water is added, it becomes calcium sulfate by a neutralization reaction. When the sawdust was added to this and mixed well, it became a medium suitable for cultivation of edible mushrooms such as shiitake mushrooms, nameko mushrooms, and oyster mushrooms. Calcium sulfate produced by the neutralization reaction did not inhibit the growth of mushrooms, but rather promoted the growth. As described above, the inventors have invented that excess sludge discharged from a food factory, a human waste treatment plant or a sewage treatment plant can be effectively used as a cultivation medium for preservative fertilizers and mushrooms. Examples will be described below.

Example 1. 3.33 kg of quick lime was added to 10 kg of non-dehydrated excess sludge discharged from the food factory, and they were mixed well with stirring. When the high heat of reaction has subsided to some extent, 2.8 kg of sawdust is added and mixed. Water content 50-60%
It was possible to produce slaked lime fertilizer containing organic matter. Further, 2.5 kg of red soil was added to this, and water was sprinkled and mixed. Next, 2.5 kg of mulch soil was added and mixed and fermented to produce an odorless fully-ripened organic fertilizer. As a result of analyzing the components of this organic fertilizer, water content 59%, nitrogen content (total nitrogen) 0.51%, phosphoric acid (phosphorus pentoxide) 0.14%, potassium (potassium oxide)
It was 0.3%. As a result of a growth test conducted on Komatsu leaves, no damage due to the amount of fertilizer applied was observed and a remarkable growth promoting effect was shown.

Example 2. Add a small amount of sulfuric acid to 10 kg of excess sludge,
H is adjusted to 4.0 to 5.0 and the temperature is adjusted to 50 to 65 ° C to promote self-digestion. After self-digestion, 1 kg of 35% sulfuric acid was added and heated for 1 hour, and then slaked lime suspended in water was gradually added to neutralize (neutralization is kept only weakly acidic). 5.2 kg of sawdust is added to this and mixed well. Water content 60
Adjusted to ~ 70%, 8 each for medium in polypropylene bag
It was filled with 00 g and sterilized at 120 ° C. for 50 minutes.
After cooling, the inoculum of the early-earning nameko species was inoculated, cultured at 22 ° C. for 3 months, and then the temperature was shifted to 15 ° C. to 18 ° C. to promote mushrooming of nameko. As a result, the yield of nameko is 20% of rice bran.
It was found that the quality and yield were superior to those of the added ones.

Effect of the invention As a result of fertilizing vegetables with fermented by adding fermented lime, sawdust, soil and the like to excess sludge, and as a result, a remarkable growth promoting effect was shown. In addition, sulfuric acid added to excess sludge, which is neutralized and added with sawdust is suitable as a cultivation site for nameko and shiitake mushrooms, promotes the growth of mycelia of mushrooms, and is good in yield and quality and effective. I found out that The present invention enables effective use of excess sludge.

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Claims (2)

[Claims] [Claim 1] Quick lime is added to excess sludge discharged from a food factory, a human waste treatment plant or a sewage treatment plant, and then straws,
It is characterized in that organic fertilizer is produced by adding and mixing sawdust, soil and the like. [Claim 2] To the excess sludge discharged from a food factory, a human waste treatment plant or a sewage treatment plant, concentrated sulfuric acid is added, and then slaked lime suspended in water is added for neutralization, and then sawdust is added and mixed to remove mushrooms. It is characterized by producing a cultivation medium.