報告書番号

U89031

タイトル（和文）

冷却水路系におけるムラサキイガイ等の付着生物防除対策－温風処理および固形物擦過法に関する検討－

タイトル（英文）

CONTROL OF MUSSEL FOULING IN COOLING WATER SYSTEMS BY MEANS OF HOT AIR INJECTION AND SOLID BODY ABRASION

概要 （図表や脚注は「報告書全文」に掲載しております）

発電所の冷却水路系に付着する付着生物は，取水量の減少と腹水器の性能低下の原因となる。アクリル樹脂製模擬水路（１０ｍ長，直径０．１ｍφ）を用いて，温風処理法および固形物擦過法によるムラサキイガイ等の付着生物防除効果について検討した。温風処理は，模擬水路の水を抜いた後電気ヒータで加温した空気を水路内に吹き込み，壁面に付着した生物を，壁面温度４０～５０℃で３時間処理する方法で行った。ムラサキイガイの付着盛期である５月，７月に各１回ずつ温風処理した結果，処理区の付着生物重量は対照区の１１～１３％に減少した。週１～２回，各３～６時間，固形物（スポンジボール）を旋回させながら水路内を通過させることにより，管壁のスライム，付着生物の幼体などの擦過除去を行ったところ，ムラサキイガイの付着量の対照（無処理）区の１０％以下に減少させることができた。

概要 （英文）

BIOFOULING OF POWER PLANT COOLING WATER SYSTEMS REDUCES THE FLOW RATES OF WATER THROUGH THE SYSTEMS AND IS A POSSIBLE CAUSE OF CORROSION OF CONDENSER PIPES. MUSSELS ARE COMMON FOULING ORGANISMS IN THE SYSTEMS AND AN INVESTIGATION IN A SYSTEM SHOWED MUSSELS COMPRISED 80% OF THE MASS OF FOULING ORGANISMS. THE OBJECTIVE OF THIS STUDY IS TO DEVELOP NEW METHODS TO CONTROL MUSSEL FOULING. HOT AIR INJECTION HOT AIR INJECTION TREATMENT WAS CARRIED OUT RANGES OF A TREATMENT INTERAVAL OF TWICE A MONTH TO EVERY TWO MONTHS,FOR ONE YEAR STARTING INDECEMBER 1987. BIOFOULING AMOUNT IN TREATED MODEL CONDUIT WAS REDUCED TO LESS THAN 0.3-11% THAT OF UNTREATED MODEL CONDUIT. HIGHER FREQUENCY TREATMENT WAS MORE EFFECITVE SO FAR AS TREATED. HOT AIR TREATMENT CARRIED OUT ONLY IN SETTLING PERIOD OFMUSSELS WAS ALSO FOUND TO BE EFFECTIVETO REDUCE MARINE FOULING. MARINE FOULING IN THE MODEL CONDUIT WHICH WAS TREATED TWO TIMES A YEAR,IN MAY AND JULY, WAS REDUCED TO 11-13% OF THAT OF UNTREATED MODEL CONDUIT. SOLID BODY ABRASION (SPONGE BALL TREATMENT) TWENTY-SIX MM DIAMETER SPONGE BALLS WERE PASSED THROUGH THE MODEL CONDUIT ONCE OR TWICE A WEEK FOR THREE OR SIX HOURS FOR ONE YEAR STARTING IN DECEMBER,1987. MUSSEL FOULING IN SPONGE BALL TREATED MODEL CONDUITWAS REDUCED TO LESS THAN 10% OF THAT OF UNTREATED MODEL CONDUIT. ALSO THIS TREATMENT REDUCED THE AMOUNT OF HYDROIDS WHICH WOULD SERVE AS A FOUNDATION FOR JUVENILE MUSSELS SETTLEMENT. HOWEVER,IT WAS DIFFICULT TO REMOVE BARNACLES BY SPONGE BALL TREATMENT AFTER THEY HAD SETTLED. GROWTHOF BARNACLES MADE IT DIFFICULT TO REMOVE HYDROIDS AND MUSSELS NEAR BARNACLES. A THREE-MONTH EXPERIMENT INDICATED THAT THE TREATMENT OF ONE HOUR ONCE A DAY WOULD BE ENOUGH FOR BARNACLE CONTROL.

報告者

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