Contaminated rivers need urgent addressing
In Bangladesh access to clean water and adequate sanitation remains a problem despite some recent improvements. In our country many people rely on highly contaminated surface water for household purposes and bathing. Consumption of this contaminated water still causes high numbers of morbidity and mortality in Bangladesh.
This is prominent both in urban areas where population densities are high, and in rural areas where water supplies are often unregulated. Given higher relevance for public health, at present most of the studies in Bangladesh have focused on drinking water supplies, while the surface waters have been ignored. Studies in Bangladesh is mainly limited to hospital based patients, but no study has measured surface water pathogen concentrations.
The limited numbers of microbial monitoring studies that have been done so far in Bangladesh are based on faecal indicator bacteria such as E. coli. Other harmful pathogens, such as infectious bacteria, viruses, and protozoa have not been included in the studies, because measuring variety of pathogens is difficult, expensive and laboratory facilities are lacking.
Although indicators themselves are usually not pathogenic, their presence in a water samples indicate possible presence of other harmful bacteria, viruses and protozoans.
For this reason indicator bacteria have been widely used instead of pathogens.
The current river contamination level is a serious public health concern in Bangladesh and needs to be addressed immediately. Climate change induced projected increase in precipitation and increased water temperatures are likely to exacerbate the problems of faecal contamination. This could be further compounded by the rapid change in socio-economic conditions in Bangladesh.
This indicates that disease outbreaks would probably become more frequent and severe in the future. Therefore, to reduce future health risks, understanding the influence of socio-economic conditions and climate change on microbial dynamics is very important. Moreover, to know the future trends in river microbial water quality is very helpful to assess the effectiveness of the existing water management facilities in the future and mitigating the associated impacts on our Rivers.
In our country wastewater is usually not treated and this untreated wastewater is discharged directly into rivers and canals. This is evident from our recent study. We measured E. coli and enterococci in the Betna river in Satkhira. We found that in 88% of the E. coli and all enterococci samples, the USEPA bathing water quality standards (235 CFU/100 ml for E. coli and 104 CFU/100 ml for enterococci) were violated. This indicates that the river Betna is unsuitable for bathing and domestic use throughout the year. The potential health risks associated with the river water's use for domestic, bathing and irrigation purposes are too large. The frequent standard failures are not surprising for the study area as the sewages enter directly to the river without treatment. The scenario is even worse in the rivers around Dhaka city due to higher population density around these rivers.
Our study revealed that adequate wastewater treatment resulted in considerable improvement of microbial water quality of the Betna River. We found that after a heavy rainfall event the bacterial concentration become very high and reduces after three to four days. However, some people want to sometimes bathe and fish in the river. Therefore, we suggest that those people do not bathe or fish in the river for at least three to four days after a heavy rainfall event, as long as major improvements of wastewater treatment are not ensured in the catchments.
Our study also reveals that the climatic factors do not strongly influence the river's bacterial Concentrations. Future emission levels will mostly depend on population growth, urbanization, sanitation coverage, sewage systems and level of wastewater treatment.
This indicates that microbial water quality of our river can be improved substantially by applying adequate wastewater treatment. Major investments to construct wastewater treatment plants are necessary to compensate for the population growth and increased volume of wastewater generation.
The current contamination level is already too high. If the investment in increasing sewage connections is not supported by adequate improvement in wastewater treatment, bacteria emissions will continue to increase and the water quality will deteriorate further. As a result, uses of the river water will increasingly be detrimental for people's health and well-being.
Our government has already made establishing effluent treatment plants mandatory for industries. However, there is a lack of strict regulation and initiative to implement domestic wastewater treatment before disposal of wastewaters into rivers.
We emphasize the need for treatment of wastewater before it is discharged into our rivers and canals. The implementation of wastewater treatment would also contribute to reaching the Sustainable Development Goal 6target 3 to halve the proportion of untreated wastewater. At least secondary level of wastewater treatment should be established immediately in the highly populated city area and gradually it should cover all population. Otherwise it will be difficult for Bangladesh to cope with the increasing waste water generation, because by 2030 the amount of waste water will be enormous and would be impossible to achieve SDG 6.3.
The writer is deputy director, Anti-corruption Commission, Dhaka