The Shaoyang, China, Night Soil Fertilizer Reclamation Plant

The Shaoyang, China, Night Soil Fertilizer Reclamation PlantAuthor(s): Ralph StoneSource: Sewage Works Journal, Vol. 21, No. 6 (Nov., 1949), pp. 992-1001Published by: Water Environment FederationStable URL: http://www.jstor.org/stable/25031173 .

Accessed: 16/06/2014 02:01

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].

.

Water Environment Federation is collaborating with JSTOR to digitize, preserve and extend access to SewageWorks Journal.

http://www.jstor.org

This content downloaded from 195.34.79.228 on Mon, 16 Jun 2014 02:01:16 AMAll use subject to JSTOR Terms and Conditions

http://www.jstor.org/action/showPublisher?publisherCode=wef

http://www.jstor.org/stable/25031173?origin=JSTOR-pdf

http://www.jstor.org/page/info/about/policies/terms.jsp


THE SHA0YANG, CHINA, NIGHT SOIL FERTILIZER RECLAMATION PLANT

By Ralph Stone

Beverly Bills, Calif.

From January through March, 1947, as part of the sanitary engineering program of the China Office, United Nations Relief and Rehabilitation Ad ministration (UNRRA), a demonstra tion night soil fertilizer plant was

built. More than a year of planning and preparation preceeded start of the actual construction. The work

was performed deep in the interior of Central China, at Shaoyang, Hunan, in conjunction with another UNRRA

sponsored project named the Agricul tural Industries Services (AIS). The

Agricultural Industries Services' high purposes were: first, io assist in the relief and rehabilitation of small in dustries disrupted by the Sino-Japa nese War, and secondly, to develop small industries that would be helpful in enriching the economy of a back

ward agricultural region. Although the fertilizer plant de

scribed was constructed to meet pre vailing needs in the Orient, the

principles of aerobic and anaerobic

digestion are also applicable to the utilization of garbage and sewage sludge. Additional study is needed of the economic factors involved in

handling and packaging digested or

ganic fertilizer. Anaerobic digestion provides gas, valuable as fuel, whereas aerobic digestion is quicker. Perhaps a combination of both processes would be advantageous.

Reasons for Plant Construction

The economical and sanitary rec lamation of fertilizer values from or

ganic wastes such as sewage, excreta,

garbage, and industrial by-products is

universally accepted as a desirable conservation practice. The main fer

tilizer chemical constituents most defi cient in soils are nitrogen, phosphate, and potash. In the United States, di

gested sludge has long been used as an

agricultural fertilizer and soil condi tioner. Undoubtedly, in the future, as more is learned about the practice of sludge digestion and processing, a better fertilizer product will result for an enlarged market. In the United

States, the sanitary aspects of sludge utilization dominate those of fertilizer reclamation. In many countries, how

ever, commercial inorganic fertilizers are not readily available and insanitary organic fertilizers must be used by farmers to maintain the soil fertility. In China, as well as in many other

lands, mixed human excrement, called

night soil, is a major source of organic fertilizer. As more than 80 per cent of the Chinese people are agrarian, the conservation of night soil fertilizer is a more important item than it would be in the more highly developed in dustrial societies with operating chem ical fertilizer plants.

Unfortunately, however, as a result of the raw excreta polluting the water

supply and food of the population, the filth diseases abound. Typhoid fever, cholera, bacilliary and amoebic dysen tery, and the worm diseases (such as

hookworm) are among the most preva lent illnesses. Nevertheless, because of the prevailing economic and social conditions in China, the health factor is not predominant, and a fertilizer

night soil treatment plant must be

justified economically by superior rec lamation of fertilizer values: in other

words, the night soil plant has to be a

self-supported undertaking. The fac tors favorable to the night soil plant

992



Vol. 21, No. 6 SHAOYANG NIGHT SOIL FERTILIZER RECLAMATION PLANT 993

paying its own way through provision of superior fertilizer reclamation are as

follows :

1. In the rice growing areas of South and Central China, accumu

lated excreta is stored by farmers in

open field pits or large earthenware

jars. Wood ashes, straw, and other waste materials are added to this night soil. An alkaline pH results, so that free ammonia forms and escapes to the

atmosphere.

Analyses of night soil samples in a

fresh state and after 3 months of field

pit storage, indicate that over one half the total nitrogen has been lost. Data for an average of five such tests are :

Fresh After Night Soil Pit Storage

Total N (%) 0.62 0.26 NH8 (%) 0.20 0.14

On the other hand, with properly controlled aerobic and anaerobic bac

teriological digestion in a night soil fertilizer plant, these nitrogen losses can be kept below 20 per cent. Thus, the 30 per cent saving in nitrogen over field pit practice represents part of the conservation value of the plant process.

2. Farmers from the countryside ob tain their extra night soil by purchas ing it either from a middleman in the

larger cities, or from a servant of a

family in the small villages. The raw excreta is more than 90 per cent water, depending on the amount of urine

present. However, a digested and dried sludge contains only about 40

per cent water. Hence, a dried sludge can be transported 6 or more times as

cheaply, and obviously with less diffi

culty than the raw night soil. Simi

larly, the dried sludge can be stored

easily until it is needed for applica tion to the fields and with little fer tilizer loss from leaching or evapora tion of ammonia.

3. The excess available supplies of

night soil exist in the larger cities of China. However, during the winter

there is no great demand for the hard

to-transport excreta. Hence, much of it is dumped away and wasted. Also,

much of the other organic wastes of the cities are now dumped away.

Garbage and street sweepings, together with industrial waste products (such as bones and viscera from abattoirs, rice hulls, leather tanning liquids, etc.) are disposed of in a haphazard man ner. By contrast, an organic ferti

lizer plant operates continuously, and can readily store the final dried fer tilizer for use of the farmer when he needs it. Thus, the fully utilized in dustrial and garbage wastes represent an additional source of organic fer tilizer.

4. Other organic fertilizers are em

ployed by the farmers of South and Central China to maintain soil fertil

ity. These fertilizers include peanut

TABLE I.?Chemical Analyses of Various Fertilizers (In Percentage by Weight)

Fertilizer Total

Nitrogen, as N

Phos phate, as

P2O6

Potash, as K2O

Raw night soil Peanut cake Green manure (from al

falfa and soya) Bone meal Animal manures Plant ashes Ammonium sulfate Calcium superphosphate Potassium sulfate Dried digested fertilizer

(aerobic digestion)

0.6 6.0-7.0

0.48-0.52 3.0-4.0 0.2-0.3

20.5

3.5?

0.1-0.12 1.0-1.5

0.08-0.09 22.0

0.06-0.03

18.0

1.5 ?

0.15 1.0-1.5

0.31-O.73

0.05-0.08 2.0-2.5

48.0

2.2 ?

cake, green manure, bone meal, gar

bage, ashes, and animal manures. Chemical analyses for these materials and other fertilizers are summarized in Table I.

Public Health Factors

Reduction of fecal-transmitted dis eases is the primary public health

problem of contemporary China. Even in Shanghai, the greatest and most modern city in China, by far the

largest number of illnesses are the re

sult of fecal-transmitted cholera, ty phoid, and dysentery, with 1,865, 1,741, and 1,446 cases reported, re



994 SEWAGE WORKS JOURNAL November, 1949

spectively, for the annual average be tween 1934 and 1946. In contrast,

diphtheria and cerebrospinal fever are

the next most prevalent reported dis

eases, with 750 and 420 annual cases,

respectively. At Shaoyang, Hunan, a water sur

vey was undertaken of 28 local wells and river watering points, which pro vide most of the water for the

population of 85,000. All the bac

teriological samples indicated that

coli-aerogenes bacteria were present, and hence that the water sources were

of unsatisfactory bacteriological qual

ity. The wells are often uncurbed and have pervious casings. Water is

withdrawn by means of privately sup

plied dirty buckets, and often surface runoff drains directly into the shallow

open wells.

A properly operated night soil plant would help control the transmission of the filth diseases. Orderly collection

of excreta would provide for proper

disposal of the night soil by well trained collectors. The controlled di

gestion of this excreta with garbage and other wastes can destroy almost all the pathogenic bacteria present and supply a superior sanitary organic fertilizer.

In anaerobic digestion at normal

temperatures, the coli-aerogenes bac

teria are destroyed at a rate of 10 to

16 per cent per day (1). For improved destruction of ascaris eggs, and thereby elimination of amoeba and worms, it

would be necessary to digest anaero

bically at temperatures approaching 150? F.

In good aerobic digestion, however,

thermophilic bacteria raise the temper ature of the composting mass to be tween 140? and 150? F. within two days. This temperature drops after an addi tional 10 days of digestion to between 10? and 120? F. and the digestion con

tinues thusly for 15 more days, after which lower temperatures prevail and

fungus growths are active in the proc ess of breaking down the organic mat

ter. The intestinal fauna and flora are

largely destroyed by these tempera tures and the other unfavorable en

vironmental factors provided by the

digestion process. Biological examina tion of samples of the aerob ically di

gesting excreta and waste material indicated that over 2,000 ascaris eggs are present per gram of the fresh mix

ture, whereas after one week of aerobic

digestion only 100 eggs per gram re

mained. These latter eggs were largely degenerated or dead.

Aesthetic Values of Plant

One can readily imagine the un

sightly and malodorous conditions that result from the haphazard collection of raw excreta and its direct utilization on agricultural produce. A fertilizer

plant incorporating a proper collection

organization would ameliorate such

problems. Concomitantly, the filthy alleys and garbage dumps would be rectified so that rats and flies would not be able to flourish on the waste

organic materials. It is estimated that an average Chinese city produces y2 lb. of garbage per day per capita, which contains only 50 per cent digestible organic material. The small quantity of waste matter is the result of the extreme economy of the impoverished Chinese people, wherein everything of value is conserved.

Perhaps the most valuable aesthetic result of a night soil fertilizer plant,

would be in the educational benefits that can develop. Farmers would learn about proper composting methods. The inhabitants of the cities and towns

would gain a concept of modern sani

tary practices. The entire population would thus be helped in terms of ad ditional fertilizer for food, a cleaner

environment, and better health.

Construction of Fertilizer Plant

Design The Shaoyang night soil fertilizer

plant was designed to handle the col lectable excreta of the population of




85,000 persons, estimated to be 10 short tons per day. To this raw night soil another 20 tons of organic material

was to be added, together with any available bone meal and a small quan

tity of lime. However, because of the unstable political situation, the local

government has never been able to deliver daily to the plant more than 25 per cent of the design capacity.

Construction

The plant is located 1,600 ft. from the geographical center of Shaoyang.

The Shao River provides the southern

boundary for the plant ; thus, the con

struction materials, and later the raw

wastes, as well as the final fertilizer

products, were easily and economically moved by boat or surface transporta tion. The site encloses an area of 1.25 acre and was formerly several rice

paddies. After construction of a fence,

the necessary cut and Jail work was

done to grade the land. The night soil

plant consists of the following com

ponents (see Figures 1 and 2) i

2 settling basins (96 cu. ft. each) for separation of the urine and feces from the collected night soil.

6 small (325 cu. ft.) aerobic com

posting pits. 1 large (1,400 cu. ft.) aerobic diges

tion tank. 2 anaerobic continuous digestion

tanks (375 cu. ft. each). 2 anaerobic fill and draw tanks

(1,170 cu. ft. each). 1 trickling filter for oxidizing 1,500

g.p.d. of urine (for manufacture of ammonium sulfate).

2 sand and gravel sludge drying beds with tile underdrains (1,600 sq. ft. each).

1 mortar and pestle bone crusher to

*-[??^A^ (?jftft-Sett/infBoL&ins #/4?

"^j /I

'C

^7> r

//oTI- ?/* valed

Wafer-^K?t |Y M

ifuluV-"-'Continuous Anaerobic /fW(g 11 j 1 \JA D.fcJtion 7an ks **/?2.

?? 7M 11

I n$/^?\^^eroi"c Ta^s^/~? y_? -Z^- iyv *\ II I II I

Pub,To,/c+ \^\JfC^^^^)\ ? \s~^^S %\MahtSo?t Fertilizer j

FIGURE 1.?Layout of Shaoyang, China, night soil fertilizer plant.




FIGURE 2.?Construction view of night soil fertilizer plant, showing batch anaerobic

digestion tanks in foreground.

handle 1,000 lb. of dry bone per day (see Figure 3).

Materials and Workers

The construction materials, insofar as possible, consisted of locally pro duced limestone, bricks, wood, bamboo, lime, tile, and other items. One of the aims of the project was to demonstrate how native materials can be employed in the development of modern sanitary

facilities. Thus, construction costs were kept to a minimum, and the local

people could easily duplicate the ferti lizer plant works. Native timber and lime mortar were employed wherever structural strength was not the govern ing factor. A minimum of hard-to-get tarpaper, cement, reinforcing steel,

plywood, diaphragm pumps, and pip ing was used. Special care was taken to build overlapping joints, caulked

?ilPIli P.ilill ,:3?iBi

-"??i

FIGURE 3.?Mortar and pestle crusher for preparing bone meal.




with a lime and tung oil preparation in order to have fairly gas-tight di

gestion tanks. Water glass, manu

factured locally, was introduced into

the walls of all the tanks in order to

help waterproof them. When possible, the tanks were constructed with earth

ramparts against the outside walls in

order to minimize wall thickness. These ramparts also provided a means

of easy access to the tank inlets at the

top. Topographic features were par

tially adopted as earth ramparts, and

the tanks were often built adjacent to one another so that they shared a common wall, thus saving on both con

struction material and labor. The

aerobic digestion tanks were provided with built-in-place air vents, false bot

toms, and extended wall bricks, all of

which assisted in the free circulation of atmospheric oxygen, so as to main tain aerobic digestion.

Over 1,087, 1,036, and 2,496 man

days of carpenter, brick mason, and manual labor, respectively, were em

ployed. Materials used included

54,013 bricks (12 X 7 X 4in.), 77 tons of lime, 1,000 pieces of timber (30 ft.

long by 8-in. diameter), 105 cu. yd. of gravel, and 39 cu. yd. of sand. One

example of the native construction

practices encountered was in the car

penter work. The tree logs were pur chased and the carpenters on the job sawed the logs by hand to the desired

plant dimensions. The permanent plant operating per

sonnel include a plant manager, a

mechanic-foreman, and a dozen work

ers for collecting the waste material and maintaining the plant operation. In addition, it is normal for Chinese

managed organizations to employ nu merous assistants and straw bosses. As

the Agricultural Industries Services was and is controlled by Chinese na

tionals, native labor practices prevail.

Public Toilets

Another part of the Shaoyang sani

tation program was the construction of

12 strategically placed public toilets

These structures were built of impervi ous materials and were designed to pro vide odorless, flyproof, and sanitary service. In addition to being a sani

tary convenience to the population, the toilets were a source of night soil col lection for the fertilizer plant.

Technical Training Program

Training of technical personnel to

operate the fertilizer plant was a neces

sary portion of the program. Four

young engineering college graduates were selected to be engineers in train

ing. To these young men belongs the credit for the materialization of the details of design, construction, and op eration of the plant and appurte

nances. In addition, several young middle school graduates were trained as mechanics and foremen. Undoubt

edly one of the most interesting and worthwhile parts of the sanitation pro gram was the opportunity of working with these enthusiastic technicians.

A small sanitary laboratory was

furnished and a competent local chem ist performed the many necessary chemical and bacteriological analyses.

Operation of Fertilizer Plant

Manufacture of Ammonium Sulfate The A.I.S. had initially planned to

construct an ammonium sulfate plant utilizing urea as a source of ammonia.

A pilot plant was built and tests were run. The project was abandoned when it was found that the fuel costs for

evaporation of the NH3 was prohibi tive. The two settling basins and the

trickling filter were designed primarily with this project in mind.

Anaerobic Digestion A great advantage of the anaerobic

digestion process is that great quanti ties of valuable fuel, in the form of

methane gas, are produced. Unfortu

nately, the digestion temperature, un less artificially maintained, is approxi

mately that of the atmosphere and is




insufficient to destroy the amoebic

cysts. For this reason, and also be cause considerable data is available on

anaerobic digestion, emphasis was

placed on the experimental aspects of aerobic digestion. Essentially the same

final fertilizer product is produced by either aerobic or anaerobic digestion.

Aerobic Digestion

It has been stated that the thermo

philic bacteria in aerobic digestion pro duce a temperature of 140? to 150? F. This heat effectively aids in destroying pathogens. The aerobic process pro duces no disagreeable odors, in con trast to the hydrogen sulphide and other smelly gases evolving in anaero

bic digestion. (However, due to the careful plant construction, no odors

escaped from the covered anaerobic

tanks.) The raw materials were added in

layers to the aerobic digestion tanks

by means of the roof inlets. First, the

ground and sorted garbage or rice straw was dumped; secondly, a layer of night soil was introduced; and fi

nally, a layer of pulverized bones and a small quantity of lime was added.

A mixture by weight of 1 part night soil, 2 parts cellulose waste, and % part bone meal was striven for. The

important consideration was to obtain a carbon-nitrogen relationship of

greater than 20 to 1. With less carbon

present there can be nitrogen losses, and bacteriological activity seems

slower. Similarly, a pH of 7.1 seems

optimum for thermophilic aerobic di

gestion. Lime was used as the pH con trol agent. Care was taken to avoid the addition of excess lime, as ammonia

gas is liberated readily from basic pH solutions containing ammonium salts. The bottoms of the digestion tanks were constructed with a 5 per cent

slope so that the surplus effluent drained into a collection pit for recirculation

by pumping or carrying it back to the

top of the digesting material. The pur

pose of this procedure was to maintain an optimum moisture content in the

digesting solids, and also to assure that all the nitrogen was extracted from the effluent. In addition, the recircu lated fluid acted as a seeding factor to stimulate digestion.

The aerobio digestion period for the first batches of material was 50 to 60

days in the warm (70? F.) humid South-Central China climate. It is believed that with proper seeding ma terial and more experienced operation this digestion time can be safely re duced to 15 to 20 days.

The smaller aerobic tank units oper ate in a similar manner to the large tank. However, the large tank pro vides for the volume needed in large scale operation. Also, the digestion

was easier to control because of the

larger amount of added material.

Digested Sludge The digested aerobic sludge is a

semi-solid mass with an appearance much like humus. The odor is not

displeasing. The digested sludge is excavated from the bottom of the tanks and placed on the drying beds in a 6 in. thick layer. The length of time

required for drying varies with the

sludge composition and the weather. In normal spring sunshine, one week of air drying is sufficient to produce a dry peat-like material. Concrete

drying beds would probably be more

satisfactory for the aerobic sludge be cause of the initial semi-solid digested state, and the avoidance of admixture of waste sand in the dried fertilizer.

An alternate method of processing the final product is to place the wet di

gested sludge into a form, where it can be lightly tamped by hand or ma chine and then placed in an open air rack and allowed to dry as a brick. This dried material (Figure 4) is sold to farmers in place of the raw excreta, and proper directions are supplied for the fertilizer's use. An educational




?^:0^&&:M

FIGURE 4.?Finished night soil fertilizer after aerobic digestion and air drying.

campaign was undertaken to acquaint

the farmers and townspeople with the significance of the fertilizer plant. The demand for the final fertilizer was

greater than the supply ; a typical con

dition in China where there is a ferti lizer shortage in most areas. Analyses of the air-dried sludge indicate that the chemical constituents are : total ni

trogen, 3.94 per cent; phosphate, as

P205, 1.50 per cent; and potash, as

K20, 2.27 per cent. The sludge con

tained 42 per cent moisture, as com

pared with an average of 96 per cent moisture in samples of raw night soil.

Unit Costs

The cost of operation of the fertilizer

plant at capacity, including deprecia tion, interest on capital, repairs, la

bor, purchase of raw materials such as

lime and bones, collection of the raw

night soil, and production and distri bution of the product at a slight profit, was calculated at $0.15 per 100 lb. of finished product. These costs can be reduced in larger-scale operation and

with more efficient design and machin

ery. The chemical fertilizer equivalent costs in China are at least 2 to 3 times

the f.o.b. price in the U. S. because of the transportation charges. At a con

servative estimate, in China nitrogen is worth $0.20 per lb.; phosphate,

$0.15; and potash, $0.10. Hence, the final organic fertilizer equivalent cost

would be $1.27 per 100 lb. Another advantage of the digested

night soil fertilizer is that it has a

buffered pH. This helps to stabilize acid soils. Furthermore, the organic fertilizer has the plus values of humus and bacterial enzymes, which stimu late crop production more than a mere

chemical analyses can indicate.

Economic Analysis for Fertilizer Plant Operation in Hong Kong

A survey of the night soil disposal methods in Hengyang, Changsha, Shanghai, Canton, and Hong Kong in dicates that the householders either dis

pose of their night soil free of charge or, in the big cities, pay a small charge for the collection service. Unfortu

nately, in Shaoyang the government was not able to organize a system of

complete and free collection. Natu

rally, this interfered with the operation of the fertilizer plant. The city of




Victoria, Hong Kong, can be utilized as an example of the economic possi bilities of a night soil plant. Victoria is chosen as an example because of its

relatively stable monetary and politi cal system.

The night soil and garbage for the

880,000 inhabitants is collected by the British Colonial Government. To fi nance this collection, property owners

pay the administration $2.00 per year per floor in each building. The night soil is picked up daily by 1,200 coolies

operating in 15 districts. The collected excreta and garbage is transported on

boats and utilized in part, although the major portion is dumped. The 10

per cent of the raw night soil that is' not wasted is stored in maturation

tanks, built during the Japanese oc

cupation, at Castle Peak, New Terri

tory, for 24 days, then sold to the

farmers, for $0.17 per 90 lb., f.o.b. The matured night soil is also delivered

by truck at a higher price. The gar

bage that is collected is at times parti ally employed for filling waste land.

Approximately 162 tons of night soil are collected each day; only 25 per cent of the population is sewered.

Also, 195 tons of garbage and sweep

ings is disposed of daily by the sanita tion department.

A night soil fertilizer plant for Vic

toria could be constructed with the

following estimated expenses:

Plant construction costs $500,000 Annual operating costs:

Depreciation and repair (10%) $ 50,000 Labor (40 laborers, 1 supt.) 13,200

Power, bones, lime, etc. 20,000

Total annual operating costs $ 83,200

The daily loading of 162 tons of

night soil and 195 tons of garbage, plus the bonemeal and other organic wastes, will shrink in digestion to about 50 tons per day of final organic ferti lizer having a minimum content of 2

per cent nitrogen, 1 per cent phos

phoric acid as P205, 0.75 per cent pot

ash as K20, and 45 per cent moisture. On the basis of wholesale chemical fertilizer prices, the commercial value of the 18,250 tons of organic fertilizer

produced yearly would be $108,200. Deduction of the operating costs leaves an estimated annual profit of $25,000.

On the basis of such analyses for both the new Shaoyang and the pro

posed Hong Kong fertilizer plants, organic fertilizer can be produced cheaply enough to undersell commer

cial chemical fertilizer, provided the

product is used locally and the ex

creta can be collected properly. Thus, the Hong Kong night soil fertilizer

plant should be able to supply farmers near Hong Kong with a superior organic fertilizer, 3 to 6 times as rich in chemi cal values as the raw night soil now

used, for the same selling price per unit weight. Furthermore, the Colonial

Government would be able to cover ex

penses, while protecting the health and welfare of the entire population. In

addition, the plant would provide more

available fertilizer and reduce trans

portation costs by 75 to 80 per cent be cause of the reduction of non-essential

organic matter and the elimination of moisture in the digestion and drying process.

Summary A demonstration night soil ferti

lizer plant has been constructed in

Shaoyang, China, under UNRRA aus

pices, to digest mixed human excre

ment, garbage, straw, bone meal, and

waste organic materials from industry, so as to produce a dry, superior, sani

tary organic fertilizer. The most prevalent illnesses in China

are the result of pollution of the food and water supply by raw human ex

crement used as a fertilizer to main tain soil fertility. The aerobic, thermo

philic, bacterial digestion process gen erates natural temperatures as high as 140? to 150? F., which effectively destroys most of the pathogenic organ isms present.




The night soil fertilizer plant must

pay its own way in terms of fertilizer

value, because of present day social and economic conditions in China. Raw

night soil cannot be thrown away be cause of the shortage of fertilizers and the necessity of maintaining crop pro duction. Data are presented that indi cate that when the raw excreta is collected by a municipality, the final fertilizer product can be sold more

cheaply than commercial inorganic fertilizer.

Acknowledgment

Full acknowledgment is made to the numerous foreign and Chinese engi neers and administrators who cooper ated in this project. In particular, the following persons were instru

mental in the completion of the Shao

yang night soil fertilizer plant : D. S. Ab ell, chief sanitary engineer, UNRRA

China Mission ; K. T. Chiang, director,

A.I.S., Chinese Government; and H. G.

Clement, director, A.I.S., UNRRA.

Reference

1. Snell, John R., lt

Anaerobic Digestion of

Undiluted Human Excreta.'' Thesis in partial fulfillment of the require

ments for the degree of Doctor of

Philosophy, Harvard University, Cam

bridge, Mass. (1942).

REGULATION OF WATER USE FOR AIR-CONDITIONING

Increased use of air-conditioning in homes as well as in office buildings is

providing a serious strain on many municipal water systems, according to the American Public Works Associa tion. A corollary problem arises in the over-loading of sewage collection and treatment facilities by the exces

sive but dilute discharges from these units.

In an effort to conserve water used in the cooling systems, as well as to

regulate its discharge into the sewers, some cities have passed ordinances

regulating use of water for air-condi

tioning. The most common regulatory method

is to restrict the discharge of water

into the sewer system to a very nomi nal amount. In Sacramento, Calif., it is unlawful for an establishment to

discharge waste water from cooling systems into the sewers at a rate in excess of 1 g.p.m. per foot of frontage of the establishment. Elmira, N. Y., does not allow air-conditioning equip ment to be installed unless a means of

water disposal other than discharge into the city sewers is provided.

New York City and Philadelphia, Pa., have restrictions on the amount of water that may be used in air-condi

tioners. All air-conditioning systems in New York using water in excess of 5 g.p.m. must be equipped with a

water-conserving unit, such as a recir

culating device or a water-cooling tower. Philadelphia requires econo

mizers where maximum water use ex

ceeds 10 cu. ft. per min.

The Washington, D. C, sanitary dis

trict will not permit water-cooled air

conditioning equipment to take water from the system at a rate greater than 0.08 g.p.m. per ton of capacity of the

cooling unit, or to discharge it at a rate

faster than that at which it is taken

into the cooling unit.

Other cities regulating use of water

for air-conditioning include Cham

paign and Urbana, 111., Rochester, N. Y., Richmond, Va., Kensola, Wis., and Reno, Nev.



The Shaoyang, China, Night Soil Fertilizer Reclamation Plant

Documents

Transcript of The Shaoyang, China, Night Soil Fertilizer Reclamation Plant