Schiffstechnik | Ship
Schiffstechnik | Ship Technology A picture nobody wants to see … © Aco Marine Sewage industry is waiting for regulators It’s about magic boxes and unrealistic views: The industry for wastewater and sewage technology is looking for effective framework conditions for the market. But regulators are not (yet) reacting It was already in March, when a group of wastewater treatment system manufacturers and environmental organisations issued a public call for a revision of MARPOL Annex IV. The intention was, and still is, the verification of the ongoing performance and discharge criteria of sewage treated systems aboard ships. The argument was: While there are rules in place for verifying discharge parameters, these relate only to type-approval testing in land-based facilities. According to the industry, there is currently no enforcement of wastewater discharge criteria once a system has been installed and becomes operational aboard ship. One of the initiators of the call was Mark Beavis, Managing Director of wastewater management system manufacturer Aco Marine. Speaking to HANSA, he confirms a rather limited response: »Up until now, we have had no direct feedback from the legislative side of the argument.« However, there were responses from various individuals/groups within the industry who are directly involved in vessel operation. According to Beavis, all have suggested that this is a situation that has to be addressed and that bringing this issue to the forefront is long overdue. »Incapable of treating sewage« So what is it all about? Beavis and his companions believe there are type-approved systems in operation at sea that are scientifically incapable of treating sewage waste. In his opinion, some technologies make claims that are simply not possible. »To claim that there is no sludge generated is not possible; sludge exists and there is no avoiding that fact. These technologies claim no sludge but this is only the ›apparent‹ case because they are flushing the sludge overboard as part of the operating cycle,« he says. A paper co-authored by this group (see box) claims: »Unfortunately, conformity assessment bodies have approved their equipment. But they have certified impossibilities and created certified ›magic boxes‹. These systems contravene science.« Beavis explains that sewage treatment plants protect the marine environment by turning raw sewage into less harmful effluent that meets specific discharge criteria set by the International Maritime Organisation. As a by-product of the treatment process sewage sludge is created that has to be either treated on board or incinerated ashore. This sludge is a by-product of all treatment processes. »But instead of being separated from the treatment process, this sludge is being flushed out in the effluent. These ›magic boxes‹ would not be able to perform no matter how well they are operated and we are very concerned about the environmental damage these systems are causing,« he argues. The group of manufacturers presents a whole list of articles emphasising perceived weaknesses in both the definition and implementation of legislation and to better clarify the spirit of the legislation »so that it becomes an unambiguous reality,« Beavis says. In his opinion, inspection bodies should fully understand the technology and processes being tested for approval and seek to clarify exactly how wastewater is being treated and how the by-products of the treatment process are being managed. »There should be full monitoring of the test regime throughout the testing cycle and detailed awareness of the process functionality at the time any samples are taken for testing and evaluation. It makes no sense to take process samples during, for example, the seawater flushing cycle of the system as the results are meaningless in such instances.« 44 HANSA International Maritime Journal 07 | 2019
Schiffstechnik | Ship Technology While the rules were tightened with MEPC.227(64) and the use of dilution water limited during performance tests, this has not prevented the certification of these so-called sludge-free systems. »Certificates have become licenses to pollute. Something is very wrong,« the authors state in the paper. Existing Guidelines do not explicitly prohibit nosludge systems but they believe the type approval regime is a contradiction to the IMO’s intentions, they say. »There is a lot at stake: the credibility of the approval regimes, the liabilities to shipowners and Aco’s managing director Mark Beavis © Aco Marine yards, a level playing field, the IMO’s environmental aspirations and ultimately, the pristine marine water that we have agreed to protect.« The authors call for IMO, its Member States and the approval assessment bodies to identify and acknowledge the issue and establish protocols in order to prevent such non-conformities from reoccurring. Beavis does not see any dramatic technological changes in the near future, »but legislatively we hope to see treatment regulations and requirements for grey water.«MM Extract from the paper Chlorination has been used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid. Today, despite concerns regarding disinfection by-products (DBP) and the advance of other disinfection technologies, such as UV, it continues to be commonly used, especially when a residual is required to control the risk of microbial re-growth. The sewage from ships includes that from onboard hospitals. So, what does it take to reach the 100 counts/100 ml limit specified in the MEPC.227(64) Guidelines? The effectiveness of chlorination depends on the wastewater quality, and the chlorine dosage that follows a time-concentration relationship. The removal of organics and particles from wastewater prior to disinfection is desirable if not essential. Other influential factors include the pH, the temperature, and the presence of ammonia, etc. Wastewater can contain more than 106~107 counts/100 ml of faecal coliforms. Conventional treatment processes can achieve 90%, or a one log, reduction. But a further 99.9%~99.99% removal, or 3~4 log-kill, is needed. To achieve this, a chlorine dosage of 5–20 mg/l is required with a chlorine contact time of 30 minutes. Chlorination is only half of the job. Since the 1970s, chlorine and other disinfectants have been found to form DBP that may be carcinogenic or harmful to the environment. Residual disinfectants themselves also cause harm to aquatic species. This has led to the adoption of a maximum residual chlorine target of 0.5 mg/l, as specified in MEPC.227(64). Although chlorine decays naturally, it takes many hours if not days. The contact time in a sewage treatment plant is typically less than 30 minutes at its designed peak flow capacity. A chlorine concentration of 5–20 mg/l will not drop below the 0.5 mg/l limit in such a short time without a de-chlorination step. De-chlorination is a must prior to discharge. Otherwise, it is impossible to satisfy both microbial and residual chlorine limits, no matter how well the plant is operated. However, de-chlorination is absent in some marine sewage treatment plants that use chlorination disinfection. The approval assessment bodies have accredited such equipment with IMO and MED certificates, based on »good laboratory results«. Thus, they have certified impossibilities. These »magic boxes« contravene science. These are non-conformities, and they turn certificates into licenses to pollute. Over the years, such »magic boxes« have found their way onto many ships, contributing to the poor performance status of the sewage treatment plants. They set the »bar«, putting conforming technologies under »competitive« pressure by forcing them into a race towards the lowest levels of functionalities. In reality, coliform concentrations in treated effluent have been found to exceed the limits by a long way across all kinds of disinfection technologies employed in marine sewage treatment plants. Ballast water management systems (BWMS), which perform less arduous disinfection duties than sewage treatment plants, may lend a useful reference. Chlorination-based BWMS have target chlorine concentrations ranging from 3 to 20 mg/l. Almost all of them incorporated de-chlorination prior to de-ballasting. Those that do not are subject to a certified minimum hold time of many days. The apparent inconsistencies between the approval processes of these two marine environmental products are hard to comprehend. The paper was co-authored by experts from Aco Marine, Wärtsilä Water Systems, RWTH-Aachen University (PIA), Holger Hamann Consulting, TEi-Testing Services, Ecomotive AS, Clean Ship Scandinavia, Headhunter Inc and Hamann AG. HANSA International Maritime Journal 07 | 2019 45
