CN101913921A - Method for preparing compound fertilizer from sludge produced by treatment of town sewage - Google Patents

Abstract

The invention relates to a method for preparing a compound fertilizer from sludge produced by treatment of town sewage. The method comprises the following steps of: (1) pretreating the sludge by acidifying; (2) heating and reacting the acidified sludge; (3) separating solid from liquid and washing; (4) neutralizing sludge silt; and (5) preparing the compound fertilizer from the sludge silt. In the compound fertilizer prepared by the method, heavy metals are removed from the sludge so that the use safety of the compound fertilizer prepared from the sludge in agricultural production can be ensured, the environmental risk of the resource utilization of the sludge is eliminated and a precondition is created for large-scale agricultural use of the sludge.

Description

A kind of method for preparing compound fertilizer with the mud after the town sewage processing

Technical field

The present invention relates to the preparing compound fertilizer method, be specially a kind of method for preparing compound fertilizer with the mud after the town sewage processing.

Background technology

Contain nutritive elements such as a large amount of organism and N, K, P and other various nutritive elements such as Ca, Mg, Cu, Zn, Fe etc. in the municipal sludge, both can be used as the nutrient of plant-growth, the structure of improving the soil again, increase soil fertility, promoting the growth of crop, is the good fertilizer of a kind of effect.

Because organic matter has the irreplaceable effect of other nutritive elements in soil fertility, often with its index as division soil fertility height.It is generally acknowledged that organic matter is high fertility greater than 1.7%, be low fertility less than 1.2%.After the founding of New, China's chemical fertilizer industry fast development, fundamental change has also taken place in farm crop Fertilization Structure.Before the 1970's, the ratio of farm manure and chemical fertilizer is 7: 3, and to latter stages in the 1980's, its ratio has been changed into 3: 7.Use inorganic fertilizer for a long time separately and not only make the soil nutriment in a fertilizer incomplete, and continuous administration, the soil salinization is hardened, ecotope is destroyed in the polluted drinking water source, and the growth along with the years simultaneously also can cause the soil organism constantly to reduce, and the soil comprehensive fertility descends.This phenomenon all has embodiment, particularly northwest and North China in the many areas of China.Contain great number of organic matters in the mud, therefore mud just can remedied organic content defective on the low side in the agricultural land soil as organic fertilizer application in the farmland, improve soil property, increase the purpose of soil fertility thereby reach

Through secular development, there has been breakthrough progress in China by introducing, digest, absorbing advanced foreign technology aspect urban sewage treatment technology.Yet as the organic component of urban sewage treatment system, the treatment and disposal technology of mud is developmental retardation but, has restricted the process of municipal sewage treatment to a certain extent.It is relevant to cause the reason of this situation and existing sludge treatment disposal technology in the world to be not suitable for China's national situation.The problem that occurs the sludge treatment difficulty abroad is early than China's many decades, the sludge treatment method of disposal that they set up in long-term practice is concluded and is mainly contained sanitary landfill, burning and soil utilization etc., these methods implement following three prerequisites: the one, need enough mud landfill space; The 2nd, need bear expensive facility investment and high working cost; The 3rd, the content of objectionable impurities in the mud such as heavy metal etc. there is strict restricted condition.And China is except also bearing economically the too high sludge treatment expense, the more important thing is that China's municipal sludge has is different from two external evident characteristics: the one, and the quantity of mud and volume are big especially, and mainly concentrate on surrounding city, do not have the space of suitable mud landfill at all; The 2nd, handle because sanitary sewage and trade effluent merge, thereby make the composition of mud very complicated, particularly heavy metal content is very high, and the soil utilization of mud is restricted.Obviously, external method for sludge treatment is difficult to be used for reference by China.At present, the most of mud of China only passes through preliminary treatment, just carries out unordered temporarily storing up or simple landfill, has not only taken large-area land resources, and has destroyed ecotope, influences HUMAN HEALTH.

Though the processing of mud has become an extremely urgent problem, and the N that contains in the mud, P, K are the necessary nutritive substances of crop growth, soil ulmin in the mud is again good soil improvement agent, but because contain objectionable impuritiess such as bacterium and heavy metal in the mud, so mud also need through suitable processing as agricultural fertilizer to want.To mud carry out the method for pre-treatment the most frequently used be compost treatment.Abroad that the composite fertilizer that is used to sell after the sludge composting dry granulated is quite general, in the U.S., there has been such factory of 65 families nineteen eighty-three, also all has mud composite fertilizer to sell mouth in developed countries such as France and Germany.When the shortcoming of compost was bad weather, process was slow, and can produce foul smell.Mud is used for agriculture production wants strict control heavy metal content wherein, to prevent that heavy metal from working the mischief to human body by food chain, for this reason, national governments have successively formulated agricultural sludge heavy-metal concentration standard, and the usage quantity of unit surface mud has been done strict restriction.Therefore, research and development utilize a kind of novel method of utilizing mud to prepare compound fertilizer, have handled above-mentioned objectionable impurities, both can produce agricultural fertilizer efficiently, can guarantee again can not produce injurious effects to environment, have good economic benefits and environmental benefit.

Summary of the invention

Technical problem solved by the invention is to provide a kind of mud after handling with town sewage to prepare the method for compound fertilizer, to solve the problem in the background technology:

Technical problem solved by the invention realizes by the following technical solutions:

A kind of mud after handling with town sewage prepares the method for compound fertilizer, may further comprise the steps:

(1) mud acidifying pre-treatment: get the mud of urban wastewater treatment firm through processed, by the volume mass of water and mud than 0.3: 1---0.3: 2 add entry, by mass concentration be 93%～98% technical grade acetic acid with the volume mass of mud than 0.5: 8-0.5: 100 add the technical grade acetic acid, behind the stirring reaction, make slurries;

(2) heating: slurries are heated to 30 ℃～80 ℃, in the process of heating, stir 15min～120min;

(3) washing: the slurries after the heat treated are carried out solid-liquid separation and wash with water, sludge silt and filtrate, the volume mass of washing water consumption and mud is than 0.5: 1--0.5: 6, filtrate enters Waste Water Treatment as waste water;

(4) neutralizing treatment of sludge silt: join lime powder in the sludge silt and be stirred to evenly, make the pH value arrival 6.5～7.5 of sludge silt;

(5) sludge silt prepares compound fertilizer: with sludge silt granulation, drying and packing, make compound fertilizer.

Beneficial effect:

The heavy metal in the mud has been removed by the composite fertilizer that the present invention makes, and can guarantee the security that the compound fertilizer with the mud preparation uses in agriculture production, has eliminated the environmental risk that recycling sludge utilizes, and is the extensive agricultural precondition of having created of mud.

Embodiment

Best embodiment of the present invention divides other scheme according to integral body, implements respectively, below by embodiment the present invention is specifically described:

Embodiment 1 mud sample is taken from Hunan sewage work, and water ratio is 82.3%, and solid content is 17.7%.Composition analysis such as the table 1 of sample for analysis after being dried to constant weight under 103～110 ℃:

The composition analysis (mg/Kg) of table 1 mud sample (butt)

Get mud 2.0Kg and place beaker, add water 1.0L, add mass concentration and be 93% technical grade acetic acid 0.04L, in the water-bath heating and stir evenly, make slurry temperature reach 60 ℃ and keep 40min, then slurries are carried out solid-liquid separation, and wash with 2L water, get sludge silt and slurries, join an amount of lime powder in the sludge silt and stir, make the pH value of sludge silt transfer to 6.0, sludge silt is prepared into the particle that diameter is 4.5mm, drying obtains compounded fertilizer of granulated, and moisture content controls to less than 9% in the dried particles compound fertilizer; Filtrate is regulated pH value to 6.0 with lime, add 4g CaS and stir 25min to separate out heavy metal, carry out solid-liquid separation then, get clear liquid and filter residue, clear liquid can be used as the cycling use of water reuse to mud acidifying slurrying liquid and solid-liquid separation washing, the Sewage treatment systems that remaining part clear liquid can be sent sewage work back to after the reuse; Weight in wet base and the dry weight such as the table 2 of the sludge silt that continuous 3 experiments obtain, heavy metal average content such as table 3 in the compounded fertilizer of granulated that 3 experiments obtain, average nutrient such as table 4 in the compounded fertilizer of granulated that 3 experiments obtain.

The weight in wet base and the dry weight (Kg) of the sludge silt that continuous 3 experiments of table 2 obtain

Heavy metal content and contrast (mg/Kg) in the compounded fertilizer of granulated that continuous 3 experiments of table 3 obtain

Composition	Hg	Cd	Cr	Pb	As	Zn	Cu	Ni
									Content	0.4	0.5	1.1	0.8	0.2	4.6	0.3	0.6
Requirement among the GB4284-1984	5	5	600	300	75	500	250	100

Nutrient and contrast (% dry weight) in the compounded fertilizer of granulated that continuous 3 experiments of table 4 obtain

Composition	Organic	TN	TP	TK
					Content	56.3	4.36	2.64	1.98
Requirement among the NY525-2002	30.0	1.0	1.0	1.0

By table 3 and table 4 as can be known, the nutrient content of the compounded fertilizer of granulated that mud prepares after treatment is higher, heavy metal content is very low, being much better than the prescribed value among GB 4284-1984 (pollutent control criterion in the agricultural mud) and the NY525-2002 (People's Republic of China's agricultural industry criteria), is a kind of fine agricultural base manure.

Embodiment 2 mud samples are taken from Hunan Yuelu District sewage work, and water ratio is 80.4%, and solid content is 19.6%.Composition analysis such as the table 5 of sample for analysis after being dried to constant weight under 103～110 ℃.

The composition analysis (mg/Kg) of table 5 mud sample (butt)

Treatment process is got mud 2.0Kg equally and is used for experiment as embodiment 1.Weight in wet base and the dry weight such as the table 6 of the sludge silt that continuous 3 experiments obtain, heavy metal average content such as table 7 in the compounded fertilizer of granulated that 3 experiments obtain, average nutrient such as table 8 in the compounded fertilizer of granulated that 3 experiments obtain.

The weight in wet base and the dry weight (Kg) of the sludge silt that continuous 3 experiments of table 6 obtain

Heavy metal content and contrast (mg/Kg) in the compounded fertilizer of granulated that continuous 3 experiments of table 7 obtain

Composition	Hg	Cd	Cr	Pb	As	Zn	Cu	Ni
									Content	0.6	0.4	1.9	1.0	0.2	5.3	0.8	0.5
Requirement among the GB4284-1984	5	5	600	300	75	500	250	100

Nutrient and contrast (% dry weight) in the compounded fertilizer of granulated that continuous 3 experiments of table 8 obtain

Composition	Organic	TN	TP	TK
					Content	58.4	5.24	2.53	1.77
Requirement among the NY525-2002	30.0	1.0	1.0	1.0

By table 7 and table 8 as can be known, the nutrient content of the compounded fertilizer of granulated that mud prepares after treatment is higher, heavy metal content is very low, also being much better than the prescribed value among GB 4284-1984 (pollutent control criterion in the agricultural mud) and the NY 525-2002 (People's Republic of China's agricultural industry criteria), is a kind of fine agricultural fertilizer.

More than show and described ultimate principle of the present invention and principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; that describes in the foregoing description and the specification sheets just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.

Claims (1)

1. the mud after handling with town sewage prepares the method for compound fertilizer, it is characterized in that, may further comprise the steps:

(1) mud acidifying pre-treatment: get the mud of urban wastewater treatment firm through processed, by the volume mass of water and mud than 0.3: 1---0.3: 2 add entry, by mass concentration be 93%～98% technical grade acetic acid with the volume mass of mud than 0.5: 8-0.5: 100 add the technical grade acetic acid, behind the stirring reaction, make slurries;

(2) heating: slurries are heated to 30 ℃～80 ℃, in the process of heating, stir 15min～120min;

(3) washing: the slurries after the heat treated are carried out solid-liquid separation and wash with water, sludge silt and filtrate, the volume mass of washing water consumption and mud is than 0.5: 1--0.5: 6, filtrate enters Waste Water Treatment as waste water;

(4) neutralizing treatment of sludge silt: join lime powder in the sludge silt and be stirred to evenly, make the pH value arrival 6.5～7.5 of sludge silt;

(5) sludge silt prepares compound fertilizer: with sludge silt granulation, drying and packing, make compound fertilizer.