Safe Drinking Water by Ecological Purification System 20190625

InternationalContribution Award of the 21^st Japan Water Awards,　June, 2019

Safe Drinking Water byEcological Purification System

NAKAMOTO Nobutada中本信忠

1.    To safe purification process without chemicals

Tap water inUeda City, Nagano Prefecture, has been supplied by slow sand filtration since1923. When the Sugadaira reservoir was constructed in 1964 upstream of thesource river, tap water in Ueda City became odor problem. At that time, algicidewas added to the  source pond and thefilter pond to prevent the smell of tap water and clog the filter pond.

The "Is the water safe to drink ?"warning (Fig. 1) was issued in 1974. Rapid sand filter using chemicals has ahigh cancer risk by the tri-halo methane formation. People has minimized theuse of chemicals.

Fig.1. "Isthe water safe to drink ?" Harris report 1974

 

2． Attentionto the role of algae and micro-animals

　Also in Japan,the cancer risk by tri-halo methane formation has become a problem, and chemicaladdition has been minimized. In Ueda City,tap water became delicious after stopping chemical addition as algicide fromaround 1980. A remarkable growth of algae was observed in theslow filtration pond and the biological community began to play an active role(Fig. 2). This was an Ecological Purification System (EPS).

Fig.2-1. Deliciouswater by stopping the algicide

  I started to study the role of algaegrowing in a filter pond from April 1984 at Shinshu University. Algae grew well on the surface of the sand layer of the shallowfiltration pond. Algal mat lifted and floated to the water surface due to thebuoyancy of oxygen bubbles produced by photosynthesis by algae (Fig. 3). It flowed out from the overflow.

 

Fig. 2-2. The floating algae flew from the overflow pipe

Thefilter has a flow from top to bottom. The water depthwas shallow and algae that became threadlike on the sand surface were predominantlypropagated. This algal mat traps turbid matter and has theeffect of not clogging the filter (Fig. 4).Algaeproduce oxygen by photosynthesis and create an environment in which microanimals in the upper part of the sand layer are more active.

 

Fig. 2-3. Floating algal mat and trapsuspended matter

  The size of organisms is much smaller than sand particle size of about 0.5 mm (Fig. 5). It is an organism that looks like trash around the sand. It is microscopic organisms of unicellular protozoa or micro-animal. At the upper part of the sand layer, a food chain has been established in which bacteria and small animals are active, eaten and eaten, and trapping and decomposition of turbidity have been performed. It was different from the image of the term of slow (sand) filtration.　

 

Fig. 2-4.  Sand andorganisms, 1 mm grid interval

 

3．Slow filtration is instant purification

Thealgae on the surface of the sand layer was food for the animals, and theanimals sought food and gathered near the surface of the sand layer (Fig. 6). Inan environment with a flow from top to bottom, the sand did not move, and thesmall animals were active on the surface of the sand, in the shade of the sandand among sand particles.

 

Fig. 3. Algae and small animals are active at the top

Theactivity of micro-organisms captured and degraded dissolved substances thatpathogens and organisms react to. The English standardfiltration rate (flow of water on sand) is as slow as 4.8 m (20 cm per hour,0.33 cm per minute) per day. Most of theorganisms were active within about 1 cm near the surface sand layer. Thetime for the water to pass through this active layer was about one minute. Itwas an instant purification by biological communities.Slowfiltration was not mechanical physical filtration with fine sand. It wasessential to develop the ecosystem in the upper layer to perform the completepurification by an Ecological function.

Whenthere is a un-expected change in water quality, the micro-organisms shrinks andturbidity passes through the biological active layer.Theturbidity which has passed is adsorbed on the surface of the sand below theactive sand layer. The sand layer was thickenedso that turbidity would not leak even in un-expected events.

 

4．Turn to a healthvillage with safe clear water

Safewater supply system was considered that can be maintained and managed byresidents in Indonesia for a social contribution activities of Yamaha MotorCompany. Mr. Sumio Yagi八木澄夫visited mylaboratory at Shinshu University. Tropical riversare usually brown water with fine colloidal mud.Thisbrown water explained the mechanism of trapping turbidity in the paddy field bythe reproduction of algae and the activity of small animals, and forming it asa faecal mass. I suggested that if this system is applied, itwill be possible to eliminate pathogens and create safe drinking water even inbrown river water without chemicals. An experimentwas conducted on a factory site in Jakarta and a real plant was constructed in1999. This plant was constructed anddonated to the village (Fig. 4-1 and 4-2).

 

 

Fig. 4-1. Algae and small animals grow well 

Fig. 4-2．Settling,shallow waterway, sand filter

  Purified water wasused for drinking and cooking. Two bottles of20-litters were supplied to all families using public taps. Theresidents decided to take the water charge for maintenance and futurefacilities repair. The water committeemanaged the public tap with a charge of 500 ml plastic bottle per every 20liters (Fig. 4-3).　

 

Fig. 4-3．Public tap and tap keeper

Villagersused this water and used only drinking and cooking, but eye sickness anddiarrhea disappeared and this village became a health village. Thereputation of this treated water was transmitted to the neighbouring village. Asthere is enough capacity for the purification of this facility, this watercommittee has developed a water supply business that purified water to the nextvillage using a water supply tank (Fig. 4-4).Wevisited this facility 10 years later. The villagers managed independently theplant without problems. 

Fig. 4-4. Water supply business to neighbouring villages

Thissystem was developed as a Yamaha clean water system.Totalnumber of installations of this system is 24 in 12 countries in Africa and Asiauntil December 2017.

 

5. Up-flowroughing filter for turbidity reduction

LuizDi Bernardo, Brazil, devised an Up-flow Roughing Filter (URF) for turbidityreduction without chemicals in 1980 (Fig. 5-1) and presented it at theInternational Conference, 1988, London.Thereport of the international joint research was published from Switzerland in1996.

Fig. 5-1. Up-flowRoughing Filter experiment device

 

Fig. 5-2. Explain URFusing a bucket model

I also tested theperformance of URF at my university. There was a functionof an Ecological Purification System to remove the turbidity . Colloidal siltymatter was hard to sink and it was adsorbed on the surface of the gravel in URFand it was trapped and decomposed by the action of a small animal. From 2006, Icontributed a water supply training course by JICA training in Miyako-jimaisland, Okinawa. I explained the mechanism of URF to remove turbidity withoutchemicals as a recent new technology (Fig. 5-2).

 

6. Water supplyto a national hospital by EPS

There was a plan toconstruct a rapid sand filter plant at a national hospital in Sri Lanka. After Mr.Motohiro Okada岡田有弘, a Japanese General Consultant Co. Ltd.surveyed in the field, he judged that the local staff could not be maintained therapid sand filter of chemical treatment. Then he came to my laboratory in 1999to ask the possibility to introduce slow sand filter system. I advised him newURF (Up-flow Roughing Filter) to reduce turbid matter without chemical, even inthe case of tropical brown turbid water (Fig. 6-1). When URF is used, safedrinking water can be produced by the activity of the biological community.

Fig. 6-1. Muddy waterof tropical rivers

Muddy brown river water iscommon in tropical continent region. Settling tank can only trap heavy turbidmatter. I recommended a sufficient pre-treatment using 3 times repetition of URFto reduce colloidal turbidity (Fig. 6-2).

Fig. 6-2. Settling tankand URF for turbid reduction

Accumulated mud on thebottom of URF drains from the drain valve from time to time. The plant composed 2 sets of purification line considering maintenanceand management (Fig. 6-3). This system does not use chemicals, but thispurification process depends on the activity of natural biological communities. Thistreated water was stored and supplied to a large hospital. Thisplant was completed and I explained the purification mechanism to localengineers in January 2001.

Fig. 6-3. Two sets of 3steps of URF

In the up-flow graveltank, fine turbidity adheres to the gravel surface.Thesmall animals play an active role, scrape off the attached turbidity and turnthem into faeces and sink them to the bottom.Fromtime to time, it is maintained and drained from the bottom.

Fig. 6-4. Explain the ecologicalpurification mechanism

Finally, algae and smallanimals on the surface of the sand filter also capture and decompose pathogensetc. The filtrate becomes safe and delicious water.Mr. AnandaWeerante, the director of the contractor who understood the mechanism, said,"Conventional is a commercial filter. This is a natural filter" (Fig.6-4).

 

7. Pesticidesare also decomposed by EPS

In 2002, I noticed thatthere is an Asia Arsenate Network (NGO in Miyazaki City) that is trying tosupply safe water by slow sand filter in Bangladesh where the groundwater iscontaminated with arsenic. I sent amessage that purification of slow sand filter based on the biological activity.They asked me that please tell us the way to remove pesticides. Iadvised that it is better to promote the use of the food chain by algae andanimals by the repetition of the up-flow roughing filter. Hardly decomposablecompound of pesticides may decompose in the faeces which is anaerobicenvironment (Fig. 7-1).

 Fig. 7-1. Safe water from arsenate and pesticide

I explained in detail the importanceof food chain in the ecological purification system and the smart technique ofup-flow roughing (gravel) filter (URF) at the EPS site of Bangladesh. Inorder to thoroughly decompose persistent pesticides, I recommended to repeat URFand I advise how to maintain the system.Thefirst water purification facility for residents based on slow sand filter in Bangladeshwas completed (Fig. 7-2 and 7-3).

 

Fig. 7-2. EPS with 4times URF

Fig. 7-3. Explainingthe role of algae and predators

The leader, Mr. KazuyukiKawahara川原一之, suggested me that the name "Slow Sand Filter" beused to misunderstand the real purification mechanism and to consider a newname for this purification system. As themechanism of purification is importance of the food chain in the ecosystemwhere the biological community plays an active role, we chose "EcologicalPurification System : 生物浄化法in Japanese." In"How to make delicious water" published in August 2005, the new term"生物浄化法Ecological Purification System" wasused.

This group subsequentlybuilt a number of new purification plants by themselves and in 2019 a new plantwith the UNICEF Fund (Fig. 7-4).

Fig. 7-4. Newconstruction by UNICEF fund in 2019

 

8. Mr. JinSchengze constructed EPS in China

Mr.JinShengzhe金胜哲, who was interested in my ecological purificationsystem, visited Shinshu University a year after publishing a technical book onEPS (2006). So, I asked for a Chinese translation, and in May2009, the Science Publishing Company in Beijing published "Safety WaterPurification Act Guidance" (Fig. 8-1).

Fig. 8-1. Chinesetranslated book on EPS in May, 2009

The great Sichuanearthquake occurred on May 12, 2008, and Mr. Jin went to Sichuan and builtthree EPS plants. He shot a video of the EPSconstruction. He came to my home in Ueda City on November 24, 2008. Iwas surprised that a 30 ton settling tank, an URF, and a EPS tank wereconstructed in a short period of about one month by human power (Fig. 8-2 and8-3).

Fig. 8-2. Constructionby human

Fig. 8-3. Theconstruction speed was surprisingly fast

In Shenyang County, Henanprovince, groundwater in the Huaihe basin was polluted due to the influence of industricaldrainage, causing frequent cancer and causing problems.Mr. Jinand Mr. Huo Daishan霍岱珊, who were working to prevent pollution, have since 2008 builta facility to make safe drinking water from contaminated groundwater in thisarea by EPS technology. The small plant(Fig. 8-4) can purify 6 tons of groundwater per day, and can supply 500 peoplewith 12 liters of water per day. The water quality has cleared all drinkingwater safety standards in China.

Fig. 8-4. Small-scalepurification system

Mr. Huo applied forconstruction funds to a number of aid organizations and constructed EPS plantsat more than 40 plants. I visited thesite in May 2016 with the guidance of Mr. Jin.Theclimate in this region was to have a roof like a greenhouse and secure solarradiation as the water freezes during the extremely cold season (Fig. 8-5). Mr.Jin said that China has a proverb called "Accumulatinggood virtues increase積善積徳"

Fig. 8-5. EPSwas covered with a translucent roo

 Fig. 8-6. The plant has two sets of EPS

  The plant built at the elementary school inAugust 2014 were 70 to 80 tons per day. This plant supplied 4,600 (include 246 schoolchildren) persons per 16 liters per day. Public tap systems was adopted for thevillagers. There were two sets of EPS line (2 m x 4 m) (Fig.8-6).

 

9. Advise for abetter plant system to Samoa

Wewent to Samoa as a follow-up survey (November 8 to 17, 2008) of JICA (JapanInternational Cooperation Agency) training on Miyakojima, Okinawa that has beencontinuing since 2006. A slow sandfilter plant that supplies water to the capital, Apia, was constructed in1984-87 with the German aid (Fig. 9-1).

Fig. 9-1. Water purification plant built with German aid

The latest Up-flow RoughingFilter, which report was published in 1996 in Switzerland, was introduced in2000. Judging from my experience, it was too small as acountermeasure against turbidity of a storm event in tropical area. Also,in this plant guideline by German consultant, the standard rate of the slowsand filter pond was 3 m per day and the depth of the filter pond was deep.This plant manual was depended mainly on the mechanical filtration withoutconsidering the biological activity.

It was thought that thefilter rate would be faster if the amount of influent water was large, and theturbidity did not settle in the settling tank.Inaddition, they thought that the higher the water pressure in the filtration,the better the water depth was. I advised that ifthe water depth is shallow, the water pressure will be small and the bubbleproduction by photosynthesis will be good, the algae will rise up, and it willbe difficult to carry out filter blockage (Fig. 9-2).

Fig. 9-2. Improvements to the Purification Function

Unlike Germany, Samoa iswarm and biologically active. In order toimprove the function and activity of the organisms, we increased the thicknessof gravel layer in URF to increase the adhesion surface where the organisms areactive, and the depth of the filter pond was shallow.Iadvised maintenance and managemen

相変わらず頑張っておられるんですね。私の家の簡易浄化槽は女房につぶされてしまいました。