JPS5888096A - Purification of filthy water and sludge by using paddy field - Google Patents

Abstract

PURPOSE:To perform the purification of filthy water, while cultivating feed rice with saved resources, by letting filthy water flow into a paddy field comprising soil premixed with sludge and cultivating a paddy-rice plant for feed rice, and letting biomembranes adhere to the lower cormus surface of the paddy-rice plant. CONSTITUTION:Ridge-shaped partition walls 8 formed by plates or piled-up soil are provided in zigzag manner with proper intervals in a paddy field 5. Filthy water such as one from a purifying cell is let flow as shown by the arrows and uniformly distributed into the paddy field 5. When the filthy water is sprinkled to the depth such that the lower cormus part 9a of a paddy-rice plant 9 cultivated in the paddy field 5 are immersed, microbes, protozoans, aquatic animals, etc. capable of decomposing the filthy water and sludge adhere to the surface of the stem leaf part 9a and exhibit purifying function. Since oxygen is ordinarily dissolved in water through the surface of the filthy water at a ratio of about 7g/ m<2>/day, the aerobic purification of the filthy water can be performed without the necessity of a means such as forcible aeration. Consequently, the formation of an offensive odor can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a method for purifying sewage and treating sludge using paddy fields in which paddy rice has been cultivated as feed for crop conversion.

Conventionally, purifying wastewater such as river water using rice fields has not been put to practical use, and only a few experimental studies have been conducted. For example, Shiga Prefectural College of Agriculture is using shallow oxidation ponds to purify polluted river water, and Akita University is using lake water as seepage ponds to return and store groundwater for use as drinking water. However, the Public Works Research Institute has attempted to recharge groundwater by filling unused paddy fields that have flooded with water during the winter, but none of these methods have been put to practical use.

On the other hand, guidance is being given nationwide to convert fallow paddy fields to crops other than rice, but grains, fodder crops, etc. are far more expensive than the standard prices in the world, and Japan is mainly a country with a humid climate. Therefore, converting to field crops requires heavy fertilization, which is not financially viable. In the end, if it remains a paddy field, there is no need for land improvement, and there is no need for heavy fertilization. It has been attracting close attention in recent years.

Fortunately, the production of feed rice using fallow rice fields has finally been designated by the government as a rice conversion crop, and has the potential to become an important pillar of feed self-sufficiency policy, but there are still issues with variety selection, cultivation methods, fertilizers, etc. It is insufficient as a system for saving resources such as pesticides and labor.

The key to the success of feed rice production is not only increasing production, but also eliminating fertilizers, pesticides, and labor savings. The key to increasing production is to cultivate ancient varieties such as red rice, which has been cultivated in Japan for 2,000 years and continues to this day. The present inventors have been cultivating the above-mentioned red rice variety for the past five years in a wet terraced rice field at the southern foot of Mt. Achieved a yield of 200 Kg of grain alone.

The above-mentioned red rice is resistant to weeds even when cultivated by scattering, and there is no need to worry about root rot even in wet fields that are constantly flooded with organic matter, so it is also possible to use waste water as a source of fertilizer by irrigating paddy fields densely planted with red rice. It is.

The present invention has been made in view of the above points, and its purpose is to mix sludge in advance into paddy field soil and ridge soil, and to mix the sludge in advance into paddy field soil and ridge soil, and to mix it into paddy fields where feed rice such as red rice has been cultivated. The sewage is gently refluxed, a microbial film is formed and attached to the surface of the lower stems and leaves of the rice plants immersed in the sewage, and the organic matter in the sewage and sludge is decomposed together with microscopic animals and aquatic animals in the rice field. By doing so, it is an object of the present invention to provide a new method that can purify sewage and treat sludge while cultivating feed rice in a resource-saving manner.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a water conduit through which any sewage such as gray water, septic tank wastewater, livestock sewage, river water, irrigation water, etc. may flow. An overflow ridge 2 made of a plate, stone, etc. is provided in the middle of the water conduit 1.

A water inlet 3 is provided near the upstream side of the overflow channel 2 to allow the wastewater to flow into the paddy field 5 surrounded by the ridges 4. On the opposite side of the paddy field 5, a drain port 6 whose water level can be adjusted is provided, so that water purified in the paddy field 5 flows out into a drainage channel 7, as will be described later.

In the rice field 5, ridge-like partition walls 8 made of boards or earth are arranged in a staggered manner at appropriate intervals, so that the waste water flows in the direction of the arrow and flows evenly within the rice field 5. It is. Nine paddy rice plants are cultivated on five sides of the rice field.

In the rice field configured as described above, when sewage is flooded to a depth where the lower foliage portions 9a of the paddy rice 9 are immersed as shown in FIG. 2, sewage and sludge can be decomposed on the surface of the foliage portions 9a. Microorganisms, protozoa, aquatic animals, etc. adhere to it and exert a purifying function. In addition, 111 liters per day are normally collected from the sewage surface.
Since around 78 parts per 2 of oxygen is dissolved in the water, aerobic sewage purification can be performed without the need for equipment such as forced backing, and no foul odor is generated.

As described above, the ability to purify sewage from the water inlet 3 to the drain 6 is as follows:
If it is 0m2, the storage volume in the rice field is 100II1
3, BOD volume load 0.05 kg/m3 day Bob)
Since a removal rate of 80% can be expected on average, it is possible to purify domestic wastewater for approximately 100 people.

The paddy soil may be any soil that has been used up to now as paddy soil, but it may also be mixed with compost, compost, highly concentrated liquid sludge, or the like.

In addition, when harvesting the paddy rice mentioned above, it is a general rule to leave the rice plants above the water surface, and tilling is usually done just before sowing the following year (practical paddy rice should be sown as densely as possible and scattered as a general rule). be.

In Fig. 3, the width of the ridge 4 is widened, a trench 10 of, for example, 30 to 50 cm wide and several tens of cm deep is dug in the center of the ridge 4, and sludge 11 etc. is poured into the trench 10. In this case, the roots 9b of the paddy rice 9 spread into the ridge 4, allowing highly efficient production of paddy rice stems and leaves for feed rice in the coexistence of soil animals and soil microorganisms, and sludge. The decomposition is performed. Incidentally, when it is necessary to treat a large amount of sludge, it is preferable that the partition wall 8 also has the wide ridge structure.

<Scope of application and social value of the present invention> The idea of the present invention is to determine the area of paddy fields and ridges where rice for feed is planted, depending on whether the main focus is on the production of feed rice and the purification of sewage, or the treatment of sludge. The feature is that the ratio to the area can be changed freely, and the decision can be made based on social conditions such as the price of each purpose. Although feed rice production remains unchanged as a target, the following targets for sewage and sludge are considered to be practical.

Furthermore, the idea of the present invention is not only applicable to the treatment of sewage and sludge and the production of feed rice, but is also consistent with advanced policy implementation and farmers' psychology. It is possible to return to it again.

(b) Treatment of livestock wastewater, sludge, etc.; (c) Organic factory wastewater and surplus sludge and human waste treatment plant surplus sludge treatment, (d) mixing treatment of pumping toilet domestic sludge and septic tank sludge,

[Brief explanation of drawings]

Fig. 1 is a plan view showing an embodiment of a rice field in which the method of the present invention can be practiced, Fig. 2 is a sectional view taken along line 1l-II in Fig. 1, and Fig. 3 is an embodiment of a wide ridge. FIG. 1... Headrace, 2... Overflow, 3... Water inlet,
4...Ridge, 5...Paddy field, 6...Drainage outlet, 7...
・Drainage channel, 8... Partition wall, 9... Paddy rice, 9a... Stem and leaf part, 9b... Root, 10... Trench groove, 11...
・Sludge patent applicant Masami Niimi and two others

Claims (1)

[Claims] Sludge is mixed in the paddy field soil and ridge soil in advance, and the sewage is gently returned to the paddy field where feed rice such as red rice is grown.
Utilizes a paddy field characterized by forming and adhering a microbial film on the surface of the lower stems and leaves of the paddy rice soaked in the sewage, and decomposing organic matter in the sewage and sludge together with microfauna and aquatic animals in the paddy field. A method for purifying wastewater and sludge.