user: Article: Incidents have seen the machines, which break down animal and food waste to produce gas for energy, fail and leak a slurry-like substance into rivers.
Afonydd Cymru, the Rivers Trust of Wales, wants tougher penalties introduced.
The Welsh Government said it would review the machines' impact on farms.
In one incident in the Tregaron area of Ceredigion, an anaerobic digester leaked into the River Teifi killing 1,000 fish.
Afonydd Cymru chief executive, Dr Stephen Marsh-Smith, said more scrutiny of the industry was needed.
"At the moment anaerobic digesters aren't regulated properly, this needs to be regulated like an industrial process," he said.
"They're often set up by contractors who don't have a lot of experience of managing them and when they're up and running there should be a full-time member of staff monitoring them.
"Where we've found anaerobic digesters have been successful there's been bunding in place, that's a secondary containment area, to make sure nothing escapes and a full-time staff member who can manage the process day and night.
"In Wales you could set up and run one of these with half a day's training, switch it on, then you've got huge pressure, and a load of toxic stuff, very often by a water course, and we're seeing that fail."
He added: "If this happened in an industrial process, it would be stopped, the directors would be found guilty of criminal pollution and prosecuted and there would be huge fines."
Chris Norman, a farmer in Pembridge, Herefordshire, has been running an anaerobic digester from his farm for the past three years.
He produces enough power to provide electricity to 850 homes, employs a full-time member of staff to run the digester and has spent an extra Â£40,000 on a secondary containment area, to make sure any material would be contained if anything did fail.
"I've built ramps, walls and concreted the whole area. So it won't run and escape from here. Also when building the anaerobic digester we made sure it wasn't near any water courses," he said.
"The nearest river is about half a mile from here. I don't believe I'm being particularly cautious or overly conscientious.
"I understand plants have been built on hillsides and next to rivers and this shouldn't happen. It doesn't matter how tight a farmer can be, we should all take preventative measures from digestate - the material remaining after the anaerobic digestion - getting into our rivers."
Mr Norman added: "At the end of the day the buck stops with me, so employing a full-time member of staff to run it and building this secondary containment area is worth every penny if it prevents a catastrophe happening."
The Welsh Government said the regulation and monitoring of anaerobic digesters was the responsibility of environment body Natural Resources Wales and it would take action where there is evidence of a breach.
A spokesman added: "Pollution incidents from farms have a significant detrimental impact on water quality and farmers must recognise the important responsibility they have in addressing this problem.
"We will be working with NRW to review the impact of anaerobic digesters used on farms."
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Summarize: Calls have been made for better regulation over the use of anaerobic digesters in Wales following a series of pollution incidents.


Article: Initial trials are promising and it is hoped the simple procedure could improve chances of survival.
The test could be used throughout the NHS within the next few years, with a clinical trial starting in GP practices across the Swansea area in 2017.
"We are delighted by the accuracy of the blood test to date," said Prof Dean Harris.
Prof Harris, Singleton Hospital consultant colorectal surgeon and honorary professor at Swansea University Medical School, is leading the project with Prof Peter Dunstan, of the university's School of Physics.
Colorectal, or bowel, cancer is the third most-common cancer worldwide, with 41,000 cases diagnosed in the UK every year.
Early diagnosis is hampered by the lack of "red flag" symptoms and patients are often not diagnosed until their chances of survival are greatly reduced.
The award-winning Swansea project dispenses with more intrusive methods of detection, using instead a laser-based blood analysis called Raman spectroscopy.
The initial study involved 160 patients from the Swansea area, some known to have bowel cancer and some known not to. It was funded by a grant from Cancer Research Wales.
Prof Harris said: "At 97%, (the accuracy) exceeds that of other testing methods, even colonoscopy."
The next stage will see the method tested on blood where it is unknown whether the patient has bowel cancer.
Researchers have now applied for a Â£250,000 grant to expand their testing.
Prof Harris said GPs could be able to offer the test to patients in just three to five years.
"There's such a global need for something like this and we have taken the technology on much further than we anticipated," he added.
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Summarize: A blood test developed by experts in Swansea could lead to bowel cancer patients being diagnosed much earlier.


Article: Earlier this week it was announced a deal was almost secure to keep "Spy Booth" in the town, after campaigners raised the money to buy it.
The piece, depicting men "snooping" on a phone box, appeared in April, three miles from government listening post GCHQ.
The local businessman, who has agreed to pay for the artwork, said he was "confident" it could be saved.
Jenny Lyon, whose boyfriend David Houghton spotted the vandalism on an early morning run, said: "There appears to be silver writing all over the three spies. It's completely ruined. It's awful.
"People have worked so hard to keep it here and then somebody overnight has ruined it for everybody."
Businessman Hekmat Kaveh, who agreed to pay an undisclosed amount to keep the artwork in place, said he believed it could be saved.
"I believe the original paint had some anti-graffiti products in it and also an anti-graffiti product was put over the top of it. I am confident that it will come off," he said.
Mr Kaveh said he was "rather surprised" local people had begun trying to remove the silver paint with a brush. "I would much rather get the professionals onto it," he said.
Experts will be called in to complete the clean-up work on Saturday and Perspex will be put over it for protection.
Gloucestershire Police said officers were carrying out inquiries and appealed for anyone who witnessed the act of vandalism to get in touch.
Campaigners have been trying to keep the artwork in situ on the corner of Fairview Road and Hewlett Road after owners of the house claimed it had been sold and workmen arrived to remove it.
Last month, Cheltenham Borough Council issued a temporary stop notice preventing further removal work from taking place on the Grade II* listed building.
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Summarize: A Banksy artwork painted on the wall of a house in Cheltenham has been defaced.


Article: A man and his wife dropped off their six-month-old daughter before arming themselves with assault rifles and opening fire at a social services centre.
Syed Rizwan Farook, 28, and Tashfeen Malik, 27, were later shot dead in a gunfight with police.
The motive for the attacks is not yet known, although President Obama later said terrorism could not be ruled out.
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Summarize:

assistant: Police in California are continuing to investigate a mass shooting in which 14 were killed and 17 others injured.