According to experts, industrial effluent is the second major source of water pollution, next to agriculture. Naturally, rivers should be able to cleanse themselves of degradable pollutants, such as oxygen-demanding wastes, as long as it is still within boundary (not overloaded) or humans do not intervene its flows. Thus there is no better, more effective, and less costly solution to water pollution than preventing it to happen in the first place.

In my opinion, prevention or cleanup should start with bottom-up approaches then followed by top-down ones. For example, water pollution from batik production activities in Pekalongan district in Indonesia. Pekalongan citizens could put political pressure on officials, by limiting batik industrial waste (point sources) being discharged to be within the river?s capacity for self-recovery, then enact laws to pool large amount of money from taxpayers to upgrade sewage treatment facilities. Stream restoration efforts could also be accompanied with planting lots of trees along the stream?s banks, which could be multiplied by sharing to public through media and hiring volunteers.

To go deeper on the technical side, there are 3 possible processes that can be done to help solve water pollution through sewage treatment: physical, biological, and chemical. These could range from using screens and grit tanks to remove large solid objects, using aerobic bacteria to remove organic wastes, to using adding nitrates, phosphates, chlorine bleaches, drain cleaners, and antibacterial soaps to kill the bacteria. Though expected to be effective, some of these processes are costly.

There is another interesting, ecology-based solution to this, coming from a real success story in Rhode Island, USA. Starts with purification tanks consisting of algae or hyacinths and cattails, flowing to artificial marsh made of sand, then aquarium tanks in which zooplankton consume microorganisms, and finally flowing cleared water into another artificial marsh for final cleansing. The estimated operational cost is similar to conventional sewage treatment plant.